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Showing new listings for Monday, 29 June 2026
- [1] arXiv:2606.27387 [pdf, other]
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Title: On the Meaning of Localization in Non-Local Quantum Field TheoryComments: 22 pages, 3 figures, published in Annalen der PhysikSubjects: General Physics (physics.gen-ph)
In this paper we explore and derive an uncertainty principle for an ultraviolet complete nonlocal quantum field theory where under our hypothesises of an induced equal time detector response kernel, we then prove that the observed localization width obeys an exact variance addition law. Then when we combine this with the ordinary Heisenberg inequality and we obtain a nonlocal uncertainty relation. The bound reduces to the usual local relation in the infrared or local limit when $E_M \to \infty$, while in the ultraviolet it implies a minimal localization length of order $L_M$. We go on to explain what this means for locality, microcausality, the interpretation of spacetime points, and the ultraviolet structure of quantum field theory. In this formulation we note and prove that spacetime will remain a Lorentz covariant continuum at the level of the manifold description but pointlike localization ceases to be a physically realizable observable notion below the nonlocality scale.
- [2] arXiv:2606.27388 [pdf, html, other]
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Title: Solar System and Atomic Clock Bounds on Locally Coupled Swampland ScalarsComments: 18 pages with 1 figure, comments welcomeSubjects: General Physics (physics.gen-ph)
We study how local measurements can constrain light scalar fields that are relevant for late time cosmic acceleration and are often discussed in connection with swampland criteria. Starting from a scalar-tensor framework, we define the relevant swampland quantities in the canonically normalized Einstein frame and relate them to Solar System, Lunar Laser Ranging, equivalence principle, and atomic clock bounds. These probes do not constrain the scalar velocity by itself but rather products of the scalar motion with microscopic couplings to matter, gravity and atomic parameters. For coupling directions that are visible to local experiments, the scalar is driven into an ultra slow present regime and this leads to severely restricting the possibility of realizing an $\mathcal{O}(1)$ de Sitter gradient through unscreened visible sector couplings alone. The refined de Sitter alternative remains viable only in restricted regions of parameter space, such as near a hilltop or under tuned dynamical evolution.
- [3] arXiv:2606.27389 [pdf, other]
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Title: Magnetron Sputtering Formation of Nanoparticles from Natural Olivine Rock for Atmospheric CO2 CaptureBrendan Matulis, Greyson Wells, Stefania Crespi, Nicola Rotiroti, Alessandro Podestà, Yuwei Zhang, Alberto Calloni, Gianlorenzo Bussetti, Fernando Cámara, Marcel Di VeceComments: 27 pages, 12 FiguresSubjects: General Physics (physics.gen-ph)
The two-birds-one-stone mineralization of CO2 by olivine, is a promising method to both capture carbon directly from the atmosphere and at the same time locking it for storage or utilization. Converting olivine to the nanoscale considerably enhances the kinetics without the need for high temperatures or pressures. Here we present the fabrication of olivine nanoparticles from a natural rock that were fabricated in a gas aggregation magnetron nanoparticle generator. The nanoparticle yield was optimized by enhancing the argon plasma sputter plasma by hydrogen introduction and varying the aggregation distance. The hysteresis of the argon sputter plasma with respect to power is a promising property towards energy efficiency. The formation of well-defined olivine nanoparticles and their subsequent absorption of atmospheric CO2 was confirmed by a suite of techniques. The olivine sputter target surface revealed an intricate interplay between the sputter plasma and olivine composition in terms of crystallinity and morphology. More broadly, this work forms the next step in the practical application of Olivine nanoparticles for economical carbon capture and storage, it also is the starting point for the use of this specific nanoparticle technology for mineral-to-nanoparticle conversion.
- [4] arXiv:2606.27390 [pdf, html, other]
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Title: Quantum-Conditioned Curvatures in Spacetime Surrounding Kerr-Newmann Black HoleA. Tawfik (Islamic U. Madinah and Ahram Canadian U. and Egyptian Ctr. Theor. Phys., Cairo and WLCAPP, Cairo), Saleh O. Allehabi (Islamic U. Madinah), M. Ur Rehman (Islamic U. Madinah), A. A. Alshehri (Hafr El Batin U. and Egyptian Ctr. Theor. Phys., Cairo)Comments: 10 pages, 3 eps figures, 0 table, accepted for publication in Astronomische NachrichtenSubjects: General Physics (physics.gen-ph)
This research examines the possibility whether the curvatures found in conventional General Relativity (GR) are the only existing ones, using both analytical and numerical techniques. To this end, we introduce a thorough investigation of Riemann curvatures in the spacetime surrounding a Kerr-Newmann black hole, which is distinguished by its specific electric charges and rotational dynamics. We apply a geometric quantization ansatz that centers on the quantization of the metric tensor, from which the complete set of field equations can be derived. The conformal transformation of the standard metric tensor upholds all the principles of GR while also extending its applicability to lower (quantum) scales. We recognize two types of Riemann curvatures. In addition to the positive curvatures present in classical GR formulations, we also find significant negative curvatures at lower (quantum) scales. This may indicate quantum sources of gravitation that classical GR does not seem equipped to explore.
- [5] arXiv:2606.27391 [pdf, other]
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Title: Testing the CCC+TL cosmology with cosmic-chronometer measurements of the Hubble parameterComments: 8 pages, 4 figures, accepted - MNRAS this https URLSubjects: General Physics (physics.gen-ph)
In a recent paper, it was shown that the Covarying Coupling Constants and Tired Light (CCC+TL) hybrid model yields the Hubble parameter $H(z)$ that is substantially different from its measured value using differential aging of quiescent galaxies as cosmic chronometers (CC). It was claimed that the fit of the CCC+TL model to the $H(z)$ data results in a best-fit value for the parameter $\alpha$, defining the strength of the co-variation of the constants, disagreeing with that for the SN~Ia data at the $\sim 6\sigma$ level. In this paper we re-examine the assumptions underlying such a comparison. Cosmic-chronometer measurements are designed to be independent of cosmological priors, but they nevertheless rely on stellar population synthesis models, isochrones, and age-dating calibrations developed within standard stellar-evolution physics. Therefore, even before introducing any specific correction factor, the present CC compilation cannot be regarded as a model-independent falsification of CCC+TL without recomputing the relevant stellar population models in that framework. In the absence of such a recalculation, we ask a more limited question: what type and magnitude of modification to the effective differential-age relation would be sufficient to remove the claimed tension? We show that a phenomenological factor of the form $\sim (1+z_t)^{-3}$ with $z_t$ being the TL contribution to the observed redshift, motivated by the scaling of gas cooling times for galaxy formation in the CCC+TL framework compared to $\Lambda\text{CDM}$, is sufficient to reduce the apparent discrepancy in $\alpha$ to $\sim 0.13\sigma$. Since $z_t = 0$ for the stellar model primarily developed from local stellar observations, the stellar-aging methods may be unable to verify $\sim (1+z_t)^{-3}$ dependence.
- [6] arXiv:2606.27392 [pdf, html, other]
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Title: Statistics of non-conserved observables in Lindblad master equationsComments: 21 pages, 1 figureSubjects: General Physics (physics.gen-ph)
We study the dynamics of observables that are conserved under the Hamiltonian evolution of a closed quantum system, but cease to be conserved when the system is coupled to a Markovian environment and described by a Lindblad master equation. Starting from the adjoint Lindblad equation, we derive elementary expressions for the time derivatives of the expectation value and second moment of an observable $O$, with particular emphasis on the case $[H,O]=0$ but $\mathcal L^\dagger(O)\neq 0$. These formulae provide a direct assessment of how collapse operators break Hamiltonian conservation laws and generate fluctuations of formerly conserved quantities. The discussion is illustrated by analytic examples: one-qubit amplitude damping, a two-qubit excitation-number model, a momentum-diffusion model in which the mean is conserved while the variance grows, and the Jaynes-Cummings model. The latter also shows the complementary case of a reservoir coupled through a conserved quantity, where dephasing can occur without changing the statistics of that quantity. We finally comment on the relation between Lindblad source terms and idealized wave-function reduction models in which local conservation may hold only statistically.
- [7] arXiv:2606.27400 [pdf, html, other]
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Title: Why does walking to the center of a merry-go-round feel so hard? Coriolis stabilization and the metabolic cost of staying on trackComments: 5 pages, 2 figuresSubjects: General Physics (physics.gen-ph)
A standard undergraduate problem has a student walk radially inward on a rotating, frictionless merry-go-round. The textbook analysis -- angular momentum is conserved, so the kinetic energy rises and the student does work -- is exactly correct for a point mass. Yet anyone who has tried it knows the effort is dominated by something the point-mass model never mentions: the muscular work of \emph{not} being thrown sideways. We make that effort quantitative with a deliberately minimal model. Treating the student as an active controller that cancels the Coriolis force at a metabolic cost $P \propto F_C^{\,n}$, we show that the cost scales as $r^{-2n}$ as the axis is approached. The widely used quadratic cost ($n=2$) gives a steep $r^{-4}$ rise; a linear cost ($n=1$) gives $r^{-2}$. We argue that this \emph{sensitivity of the prediction to the cost model} is the most useful thing in the problem: it forces students to see how a modeling assumption, not just an algebraic step, drives a physical conclusion. We give an order-of-magnitude estimate (explicitly flagged as such), a one-line entropy-production / efficiency argument that connects the exercise to non-equilibrium thermodynamics, a feedback (PD-controller) reformulation that reproduces the same scaling, and a back-of-the-envelope experiment students can do on a playground with a phone and a heart-rate strap. The material is aimed at an intermediate-mechanics or biophysics elective and is designed to teach model validity, assumption sensitivity, and the idea that staying alive and on-course has a thermodynamic price.
- [8] arXiv:2606.27404 [pdf, html, other]
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Title: Collective modes and screening in an electric-magnetic dual plasmaComments: 13 pages, 4 figuresSubjects: Plasma Physics (physics.plasm-ph)
We study the linear response of an effective relativistic two-fluid medium carrying separately conserved electric and magnetic charge currents. The model is defined by the duality-symmetric Maxwell equations with electric and magnetic sources, together with Lorentz-force dynamics for two fluids with independent inertia and possible Carter-type entrainment. The magnetic component is treated as an effective charge-carrying constituent, so the analysis uses only the closed two-fluid equations. Around a homogeneous, neutral, and unmagnetized background, the transverse electromagnetic response contains two stable branches whose cutoffs are set by the electric and magnetic plasma frequencies and are exchanged by electric--magnetic duality. In the longitudinal sector, entrainment mixes the electric and magnetic density oscillations, turns their crossing into an avoided crossing, and gives the stability condition $ \kappa^2<1 ,$ equivalent to positive definiteness of the two-fluid momentum matrix. Resolving the magnetic component into monopole and antimonopole species gives a neutral branch selected by magnetic charge conjugation \(C_m\). In this branch the net magnetic current vanishes, so the long-range monopole field is absent, while the total magnetic density can still produce screened collective response. The resulting picture is that magnetic charge can be statically hidden but dynamically visible. A robust observable signature is the density scaling $\omega_{\rm coll}^2\sim\omega_{pm}^2\propto n^0_{(m)},$ which may survive dissipative broadening even when sharp ideal-plasma poles are not resolved. We briefly comment on possible dyonic interpretations of magnetically neutral composites, but the linear-response results do not rely on that interpretation.
- [9] arXiv:2606.27445 [pdf, html, other]
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Title: Analysis of Nonlinear Random Polarization in Dispersive DielectricsComments: 20 pagesSubjects: Optics (physics.optics); Numerical Analysis (math.NA)
We present a study on the time-domain propagation of electromagnetic waves in dielectric materials modeled by a nonlinear Debye medium with random perturbations. Polynomial Chaos Expansions are employed to transform the random nonlinear Debye polarization model into a deterministic framework. We extend the Yee discretization to the resulting coupled system, establish second order accuracy, and verify convergence numerically. We investigate the sensitivity of nonlinear properties to uncertainty, particularly when the amplitude of the input signal is large. Given the challenges in manufacturing where uncertainties can cause optimal parameters to vary and potentially disrupt nonlinear effects, our approach incorporates these uncertainties within the simulation. This can enable the model-based design identification of realizable materials that maintain their desired effects despite variations. The findings from this study contribute to a deeper understanding of wave propagation in complex media, with potential implications for applications in optical communications, material science, and electromagnetic wave control.
- [10] arXiv:2606.27450 [pdf, html, other]
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Title: Sawtooth suppression by flux pumping on HBT-EPJournal-ref: Nuclear Fusion 64 (4), 046020 (2024)Subjects: Plasma Physics (physics.plasm-ph)
This study examines the mechanisms underlying sawtooth suppression in the High Beta Tokamak-Extended Pulse (HBT-EP) device. It is observed that strong-intensity sawtooth activities correlate with reduced-amplitude MHD edge modes which are identified as $m/n=3/1$ external kink modes (XK), while sawtooth suppression correlates with larger and saturated edge mode amplitudes. To further investigate these correlations, the plasma-wall coupling was manipulated by adjusting the positions of the conducting walls in HBT-EP. It was found that strong sawtooth events occur when the normalized wall radius $b/a$ is within a critical value. This implies that the plasma-wall distance must be sufficiently small to ensure effective stabilization of the edge mode. Even slight differences in major radius result in significantly different discharge styles, categorized as ``sawtoothing discharges'' and ``sawtooth-suppressed discharges'' respectively. Through a series of mode structure analyses, we confirm the coexistence and coupling of the $m/n=1/1$ helical core (HC), $m/n=2/1$ tearing mode (TM), and $m/n=3/1$ XK during sawtooth suppression, and that this coupling induces anomalous current broadening. Based on these findings, we conclude that sawtooth suppression in the HBT-EP tokamak is consistent with the process of magnetic flux pumping.
- [11] arXiv:2606.27453 [pdf, html, other]
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Title: Gyrokinetic Theory of Linear Gravitational Flute Interchanges with Flow Shear StabilizationComments: 32 pages, 4 figuresSubjects: Plasma Physics (physics.plasm-ph)
A collisionless electrostatic gyrokinetic theory is developed to describe how the presence of a differential velocity shear can help stabilize linear gravitational flute interchanges in slab geometry. This is made possible because the velocity shear acts to increase the perpendicular wavenumber of the unstable modes with time. Eventually, a threshold wavenumber is crossed where the effect of gyroaveraging, captured by the \(J_0\) Bessel function in the gyrokinetic equation, results in a damping of the instability by nature of \(J_0\) being a decaying sinusoidal. However, transient amplification, responsible for subcritical turbulence, can still occur. Numerical comparisons are made with a Magnetohydrodynamic model with gyroviscous corrections as well as the GX gyrokinetic code. It is demonstrated that an increasing shear acts not only to accelerate the stabilization effect but also to reduce the overall transient amplification.
- [12] arXiv:2606.27458 [pdf, html, other]
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Title: Direct imaging of enantiomer-specific orientation dynamics in unidirectionally rotating chiral moleculesKenta Mizuse, Ilia Tutunnikov, Long Xu, Yuhei Oyagi, Naoya Sakamoto, Ryo Kondo, Allan Huang, Roman V. Krems, Ilya Sh. Averbukh, Yasuhiro OhshimaComments: 10 pages, 7 figuresSubjects: Chemical Physics (physics.chem-ph); Atomic Physics (physics.atom-ph); Optics (physics.optics)
Selectively controlling the dynamics of molecular enantiomers underlies advances across chemistry, biology, and physics, yet direct imaging of enantiomer-specific motion has so far remained elusive. Here, we image ultrafast enantioselective orientation dynamics in isolated chiral molecules. Unidirectional coherent rotation induced by a femtosecond laser-pulse pair generates equal and opposite out-of-plane orientations of the two enantiomers. Applying this scheme to 2-methyloxirane, we follow the rotational wave packets by time-resolved Coulomb explosion imaging with two orthogonally arranged detectors. The measured angular distributions reveal that the unidirectional rotation is identical for both enantiomers, while the out-of-plane orientations are mirror images that persist through both early-time quasi-classical and quantum dynamics regimes, in quantitative agreement with simulations. We demonstrate that full angular distributions provide richer dynamical information, with some qualitatively different distributions yielding similar orientation factors upon integration. Our approach opens a route to real-time observation and control of chiral dynamics in the gas phase.
- [13] arXiv:2606.27463 [pdf, html, other]
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Title: Nonlinear Freezing of Vibrational Polariton Transport via Mesoscale SimulationsSubjects: Chemical Physics (physics.chem-ph); Computational Physics (physics.comp-ph)
Two-dimensional real-space imaging of vibrational polariton transport in planar Fabry--Pérot microcavities is numerically simulated via the mesoscale cavity molecular dynamics approach, which self-consistently propagates $\sim\!2\times10^4$ realistic molecular simulation cells on a two-dimensional grid coupled to the same number of cavity modes. Beyond the well-known polariton ballistic-to-diffusive turnover in the linear response regime, these atomistic simulations reveal a nonlinear freezing mechanism of vibrational polariton transport, i.e., under strong pumping of the upper polariton, the initially ballistically propagating upper polariton completely freezes and localizes energy to molecules at specific locations. This mechanism originates from pump-induced breaking of the in-plane translation symmetry: significant molecular excitations at the pulse hot spot broaden the polariton density of states, thus funneling population to the $k_{\parallel}\rightarrow 0$ band edge with vanishing group velocities.
- [14] arXiv:2606.27470 [pdf, other]
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Title: Universal framework for the design of near-zero refractive index photonic crystalsComments: 18 pages, 6 figuresSubjects: Optics (physics.optics)
Near-zero-index (NZI) media are of great interest for controlling light-matter interactions, but homogeneous NZI materials in the telecom band remain limited and often suffer from significant losses. Photonic crystals provide an attractive alternative due to their tunability and use of low-loss constituent materials. This work presents a predictive framework for designing epsilon-near-zero (ENZ), mu-near-zero (MNZ), and epsilon-and-mu-near-zero (EMNZ) photonic crystals. We demonstrate an equivalence between Dirac cones and EMNZ behavior, showing that a Dirac cone at the Gamma point is both necessary and sufficient to obtain an effective EMNZ response under normal incidence. This result implies that the presence of a Dirac cone fully determines the NZI response of a photonic crystal, independent of the material composition. The prediction is based on mode symmetry universality and effective medium theory. The approach enables switching between ENZ-MNZ and EMNZ regimes through geometric tuning of the unit cell. It is validated on triangular and rectangular lattices. Overall, this work provides a predictive design strategy for NZI photonic crystals, replacing trial-and-error optimization. It may also impact metamaterials in the telecom regime and applications in quantum communication.
- [15] arXiv:2606.27489 [pdf, other]
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Title: Non-dipole effects in two-photon double ionization of the K-shell of a beryllium-like atomic ionComments: 6 pages, 2 figuresSubjects: Atomic Physics (physics.atom-ph)
In the second order of the non-relativistic quantum perturbation theory and outside the framework of the dipole approximation for the operator of the radiation transition between continuum-spectrum states, the analytical structures and absolute values of the generalized cross-sections of the two-photon double ionization of the K-shell of beryllium-like ions of titanium (Ti18+), iron (Fe22+) and zinc (Zn26+) atoms were predicted. It has been established that taking into account non-dipole effects by several orders of magnitude (giant non-dipole effect) reduces the generalized cross-sections calculated within the framework of the dipole approximation. It has also been established that at high (12.5 - 28 keV) energies of the absorbed photons, the generalized cross-section of the two-photon double ionization of the K-shell is several orders of magnitude greater than the generalized cross-section of the single ionization. At the same time, as was to be expected, the transition from a neon-like ion to a beryllium-like ion is accompanied by a significant increase in the role of non-dipole effects.
- [16] arXiv:2606.27513 [pdf, html, other]
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Title: Toward a Hybrid Digital Twin of Society: Quantifying Cognitive-Spatial Linkages Through Online-Offline Feedback NetworksSubjects: Physics and Society (physics.soc-ph)
Digital platforms increasingly shape how people experience and navigate cities, linking virtual information seeking with physical mobility. Despite this interdependence, online and offline activities are often studied separately in urban mobility research. This paper introduces the Feedback Network, a computational framework that captures interactions between cognitive activity in digital environments and behavior in physical space. Using Google Search and Location History data from the same individuals, collected through a data donation framework in Budapest, Hungary, between 2018 and 2022, we examine how online search patterns and offline visitation behavior co-evolve. We combine semantic and spatial analytical approaches. Radius of gyration is adapted to measure variation in geographic mobility and semantic exploration, enabling comparison between physical movement and online cognitive dispersion. A Feedback Network models transitions between search-related and location-related activity clusters and is evaluated using Concentration Entropy, which measures whether behavioral flows are concentrated around routine pathways or distributed across exploratory transitions. The results show that online exploration is more concentrated than offline mobility, suggesting narrower and more repetitive semantic interests, while physical movement remains relatively diverse. Persistent linkages between search and visitation activities related to retail and business services indicate stable cognitive-spatial behavioral loops. The COVID-19 pandemic disrupted spatial routines more strongly than cognitive exploration, widening the gap between digital engagement and realized movement. The findings demonstrate that urban mobility depends on the interaction between informational exposure and spatial encounter and provide a foundation for Hybrid Digital Twins of Society.
- [17] arXiv:2606.27524 [pdf, html, other]
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Title: Quantitative interpretation of Brookfield DV3TLV measurements: shear rate conversion, correction factors, and applicability limitsComments: 39 pages, 27 figures, 5 tables. English translation of the initial draft. The corresponding Russian paper is under peer review and will be substantially revised. The definitive English Version of Record will be subsequently translated and published by Pleiades Publishing / Springer NatureSubjects: Geophysics (physics.geo-ph); Fluid Dynamics (physics.flu-dyn); Instrumentation and Detectors (physics.ins-det)
The flow behavior and hydrodynamic characteristics of fluids in rotational viscometry systems are investigated using the Brookfield DV3TLV viscometer, with emphasis on measurement reliability and applicability limits of different measuring geometries. The results are compared and validated using the high-precision MCR 302 rheometer manufactured by the Austrian company Anton Paar. Both Newtonian (water and glycerol) and non-Newtonian fluids (guar-based gels), exhibiting fundamentally different viscosity-shear rate behavior, were included in the study. Based on the comparison of measurements obtained with the Brookfield DV3TLV viscometer and the MCR 302 rheometer, empirical coefficients were determined that relate the spindle rotational speed to the shear rate, taking into account the geometry of the measuring systems. Analysis of the Reynolds number range showed that laminar flow conditions were maintained for all measurement systems, which justifies the application of quasi-static models that neglect possible flow turbulence within them. Comparison with high-precision measurements performed on the MCR 302 rheometer showed that, with appropriate interpretation, the data obtained using the Brookfield instrument can be used to estimate the real viscosity of process fluids with an accuracy specific to each geometry and its operating conditions. The proposed methodology enables reliable characterization of flow properties in rotational systems and can be applied in engineering practice and laboratory analysis of complex fluids, especially at oil and food production facilities where high-end rheometers are unavailable or impractical to use. The study is formulated within the framework of experimental fluid mechanics and non-Newtonian flow characterization.
- [18] arXiv:2606.27534 [pdf, other]
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Title: Ridge-filter crosstalk in conformal proton FLASH planning: dependence on beamlet pitch and iterative mitigationZongsheng Hu (1), Yuting Li (1), Henry Meyer (1), Xiaochun Wang (1), Susan L. McGovern (2), Emil Scheueler (1), Radhe Mohan (1), Uwe Titt (1) ((1) Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas, (2) Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas)Subjects: Medical Physics (physics.med-ph)
Objective: Patient-specific ridge filters (PSRFs) can enable conformal single-energy proton FLASH delivery without energy switching. However, converting optimized spot-based dose distributions into physically adjacent ridge-filter structures may introduce inter-beamlet modulation errors not captured by conventional isolated-spot optimization. This study characterized ridge-filter (RF) crosstalk, evaluated its dependence on the beam-width-to-pitch relationship, and developed an iterative mitigation strategy. Approach: A Monte Carlo dose influence matrix was generated for monoenergetic proton beamlets passing through RFs of varying thickness. A baseline spot-weighted IMPT plan was optimized to meet dose constraints and converted into PSRF geometries. PSRF dose distributions were calculated by explicitly modeling the PSRF in the scanned beam path. RF crosstalk was quantified by comparing PSRF and baseline IMPT plans. Lateral beamlet spacings of 8, 10, 12, and 15 mm were evaluated using gamma analysis, DVH metrics, and mean relative dose difference. An iterative re-optimization method was tested in water-phantom and patient CT geometries. Results: RF crosstalk produced hot and cold spots, reducing agreement between PSRF and baseline IMPT plans. For the same spot size and target geometry, crosstalk increased as beamlet spacing decreased. Iterative re-optimization substantially reduced dose discrepancies, lowering the mean relative dose difference in the target from 8.9% to 3.4% in water and from 3.7% to 1.8% in CT. Significance: RF crosstalk is an important source of dose inconsistency in ridge-filter-based conformal proton FLASH planning. Its dependence on the beam-width-to-pitch relationship and mitigation through iterative re-optimization provide a practical framework for improving the accuracy and robustness of patient-specific single-energy proton FLASH delivery.
- [19] arXiv:2606.27540 [pdf, other]
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Title: The multifractal nature of turbulent energy dissipationComments: 56 pages, 41 figuresJournal-ref: J. Fluid Mech. 224, 429-484, 1991Subjects: Fluid Dynamics (physics.flu-dyn)
The intermittency of the rate of turbulent energy dissipation ${\epsilon}$ is investigated experimentally, with special emphasis on its scale-similar facets. This is done using a general formulation in terms of multifractals, and by interpreting measurements in that light. The concept of multiplicative processes in turbulence is (heuristically) shown to lead to multifractal distributions, whose formalism is described in some detail. To prepare proper ground for the interpretation of experimental results, a variety of cascade models is reviewed and their physical contents are analysed qualitatively. Point-probe measurements of ${\epsilon}$ are made in several laboratory flows and in the atmospheric surface layer, using Taylor's frozen-flow hypothesis. The multifractal spectrum $f({\alpha})$ of ${\epsilon}$ is measured using different averaging techniques, and the results are shown to be in essential agreement among themselves and with our earlier ones. Also, long data sets obtained in two laboratory flows are used to obtain the latent part of the $f({\alpha})$ curve, confirming Mandelbrot's idea that it can in principle be obtained from linear cuts through a three-dimensional distribution. The tails of distributions of box-averaged dissipation are found to be of the square-root exponential type, and the implications of this finding for the $f({\alpha})$ distribution are discussed. A comparison of the results to a variety of cascade models shows that binomial models give the simplest possible mechanism that reproduces most of the observations. Generalizations to multinomial models are discussed.
- [20] arXiv:2606.27562 [pdf, html, other]
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Title: Two-Dimensional Locally Adaptive Non-Hydrostatic Extension of Shallow Water EquationsSubjects: Fluid Dynamics (physics.flu-dyn); Numerical Analysis (math.NA)
We introduce a two-dimensional non-hydrostatic model for shallow water wave dispersion. The model is based on a locally adapted application of a non-hydrostatic correction to the hydrostatic shallow water equations (SWE) in a predictor-corrector scheme. Applying the non-hydrostatic correction uniformly to the entire domain demands a high computational cost, since an elliptic system of equations needs to be solved for the correction terms. We demonstrate that by determining the area where the non-hydrostatic effects are significant, and applying the correction only locally, the computational effort can be reduced by approximately 40\% without sacrificing accuracy in tsunami-like scenarios. As indicators for the non-hydrostatic effect, we use the ratio between total water depth and surface elevation, as well as horizontal velocity norms. Results are shown for several well-known test cases, including wave trains over a semi-circular shoal, static, and moving bottom tsunami-like wave propagation.
- [21] arXiv:2606.27597 [pdf, html, other]
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Title: Toward a Universal Framework for the Internal Gravity Wave SpectrumLeticia Fabre-Lima (1), Jeffrey Early (2), Miles A. Sundermeyer (1) ((1) School for Marine Science and Technology University of Massachusetts Dartmouth, (2) NorthWest Research Associates)Comments: Submitted to Journal of Physical OceanographySubjects: Fluid Dynamics (physics.flu-dyn); Atmospheric and Oceanic Physics (physics.ao-ph)
The Garrett-Munk (GM) spectrum has long provided a canonical model of the oceanic internal gravity wave field. However, it relies on hydrostatic assumptions and idealized stratification that limit its applicability where non-hydrostatic dynamics, vertical boundary effects, or non-monotonic stratification are important. Here we develop a generalized framework for the internal wave spectrum based on non-hydrostatic vertical modes formulated in horizontal wavenumber-vertical mode space. Energetic orthogonality among wave modes requires that such a formulation be cast in horizontal wavenumber space rather than frequency space. In this formulation, the deformation radius associated with each vertical mode provides a proxy for distinguishing hydrostatic and non-hydrostatic regimes. Vertical modes are obtained numerically from the fixed-K Sturm-Liouville problem, allowing arbitrary stratification and multiple turning depths. Combined with a generalized spectral function, the formulation yields expected distributions of horizontal kinetic, vertical kinetic, and potential energy as functions of depth, frequency, and horizontal wavenumber. Example applications illustrate departures from GM theory associated with boundary effects and non-hydrostatic dynamics, including improved representation of vertical variance and high-frequency vertical kinetic energy, while reproducing observed features of horizontal wavenumber spectra.
- [22] arXiv:2606.27612 [pdf, other]
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Title: Enhancing Co-packaging Optics Enabled Silicon Photonics Security Assurance Hardware FingerprintingLiton Kumar Biswas, M Shafkat M Khan, Himanandhan Reddy Kottur, Hao Wang, Hamed Dalir, Navid AsadizanjaniComments: Author manuscript version of paper published in IMAPSource Proceedings 2025. Final published version available through IMAPS. 6 pagesJournal-ref: IMAPSource Proceedings 2025 (Symposium) : 7-12, 2025Subjects: Optics (physics.optics); Computer Vision and Pattern Recognition (cs.CV); Image and Video Processing (eess.IV)
Silicon photonics enables integration of optical components using standard semiconductor processes, greatly improving data communication bandwidth and energy efficiency. However, photonics integrated circuits (PICs) face unique security challenges, such as counterfeit or tampering threats, that conventional electronic security methods do not address. We propose a novel hardware fingerprinting technique that embeds two dimensional photonic crystal patterns into the density control filler regions of a PIC. Each PhC pattern is designed to resonate a specific visible to near infrared wavelengths, producing a distinctive optical signature (based on wavelength, polarization, and incident angle) for each device. Finite difference time domain (FDTD) simulation using ANSYS Lumerical is employed to optimize nanostructure dimensions and spacing so that each device's reflection/absorption spectrum contains unique narrowband peaks. No extra fabrication steps or materials are required beyond standard lithography, keeping costs low. The embedded nanostructures have sub-50nm precision, making forgery extremely difficult. Our method yields a high resolution, scalable fingerprint for silicon photonic chips, enabling cost-effective device authentication and improved supply chain security.
- [23] arXiv:2606.27615 [pdf, other]
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Title: Interface tracking with Microscale Topological Surgery for two-dimensional filament breakupComments: 45 pages, 23 figuresSubjects: Fluid Dynamics (physics.flu-dyn); Numerical Analysis (math.NA); Computational Physics (physics.comp-ph)
We design and implement a Microscale Topological Surgery (MTS) algorithm to detect and enforce topological transitions in two-dimensional tracked interfaces. The method combines classical Lagrangian tracking with an intermittent topological processor that: (i) constructs Eulerian snapshots from which an interface family with microscale-resolved topology is extracted, (ii) infers adjacency topology between dual Lagrangian and Eulerian interface families, and (iii) performs interface surgery to stitch the two families together across microscale defect regions. A novel long-time nonlinear alternating-shear flow is introduced, in which repeated stretching and folding generate rich multiscale interface dynamics with filamentation at microscales. Using the MTS algorithm and a posteriori geometric and material diagnostics, we compute and visualize microscale filament-breakup dynamics. Error analysis and scaling studies demonstrate second-order geometric convergence and optimal computational scaling of the MTS algorithm, with topology-processing costs comparable to those of the underlying Lagrangian evolution. Ensemble simulations generated by pseudo-random perturbations of the flow further reveal coherent droplet size distributions and statistically robust filament-breakup dynamics.
- [24] arXiv:2606.27620 [pdf, other]
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Title: Inferring solar-wind plasma structures from sparse probe trajectories using recurrent reduced-order learningComments: 19 pages, 16 figuresSubjects: Plasma Physics (physics.plasm-ph); Space Physics (physics.space-ph)
In space plasma studies, spacecraft measurements often provide time histories of the solar-wind plasma. However, many heliospheric plasma processes are organized over spatial scales that cannot be directly resolved by limited local sampling. This creates a persistent challenge: how to use limited probe measurements to recover the spatial plasma distributions needed to interpret evolving solar-wind structures. In this work, we present a recurrent reduced-order learning framework to address this challenge. The method is demonstrated using WSA-ENLIL solar-wind simulation data to reconstruct two-dimensional meridional and equatorial fields from a small number of virtual probes, with radial velocity and plasma density considered as target quantities on both planes. From sparse temporal probe signals as inputs, the model recovers the dominant radial and latitudinal variations in the meridional plane and the spiral-shaped organization of the equatorial solar wind. It is also able to reconstruct spatial distributions of dynamically coupled plasma fields not directly sensed. Sensitivity studies are performed to assess the dependence of reconstruction accuracy on key parameters of the machine-learning framework: modal rank, number of probes, and input-history length. The outcomes underline the methodology's promise as a practical route for extracting spatial plasma-state information from spacecraft measurements in support of studies on the underlying physics of space and solar-wind plasmas.
- [25] arXiv:2606.27626 [pdf, html, other]
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Title: Self-organized robustness in mean-field interacting systemsComments: 14 pages, 7 figures. 43 SI pages, 9 figuresSubjects: Biological Physics (physics.bio-ph); Statistical Mechanics (cond-mat.stat-mech); Adaptation and Self-Organizing Systems (nlin.AO)
Self-organization is a defining feature of living systems, with order often maintained through interactions between constituent units rather than centralized feedback. We introduce a tractable mean-field model of self-organized robustness, formulated as meta-optimization over the system's response to perturbations. The resulting interaction structure has an intuitive picture as a dynamically modulated landscape (``seascape'') whose shape is determined self-consistently to accelerate relaxation back to equilibrium. The collective dynamics follows an optimized Wasserstein gradient flow toward an attractor in the space of collective states. When communication is limited, interactions preferentially encode slowly relaxing modes and modes that are frequently perturbed. The model further shows that robust collective states are associated with flatter equilibrium landscapes and predicts a continuum of intermediate ``reservoir states'' in such systems. The model offers a perspective of self-organization as a hierarchical associative memory that operates on the scale of a collective of interacting computational units.
- [26] arXiv:2606.27735 [pdf, html, other]
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Title: Optothermal Actuation of Unidirectional Thermo-osmotic FlowsComments: 10 pages, 10 figuresSubjects: Fluid Dynamics (physics.flu-dyn); Applied Physics (physics.app-ph)
In this paper, we experimentally demonstrate the microscale direction control of thermoosmotic flows using a focused-laser heating. The key is the off-center laser irradiation on an immobilized light-absorbing microparticle, which generates a nonuniform, asymmetric heat source. The resulting thermo-osmotic flows are evaluated using the optically trapped particle tracking velocimetry (ot-PTV), presented in our preceding paper (T. Tsuji, et al., Physical Review Fluids 11, 034901 (2026)). It is shown that the flow characteristics can be modulated by the ionic strength of a sample solution and/or the surface molecular coating of the substrate. In particular, the significance of ionic strength on thermo-osmotic flows are discussed based on the surface potential of the substrate measured by frequency-modulated atomic force microscopy.
- [27] arXiv:2606.27778 [pdf, html, other]
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Title: Statistical equilibria of two-dimensional turbulent flows for generic initial vorticity fields on a sphere, calculated on the basis of the original Miller-Robert-Sommeria theoryComments: 47 pages, 6 figuresJournal-ref: Fluid Dyn. Res. 56 065509 (2024)Subjects: Fluid Dynamics (physics.flu-dyn); Adaptation and Self-Organizing Systems (nlin.AO); Chaotic Dynamics (nlin.CD); Pattern Formation and Solitons (nlin.PS)
Based on the original Miller-Robert-Sommeria theory, we explicitly compute a statistical equilibrium of two-dimensional turbulent flow on a sphere for a generic initial vorticity field introduced in a previous study. The macroscopic vorticity field corresponding to the obtained statistical equilibrium has a quadrupole structure. The resulting quadrupole structure is topologically consistent with the final state of the long-term time integration of the vorticity equation. However, the statistical equilibrium does not predict the formation of concentrated vortices as seen in the time integration. We also calculate statistical equilibria for the initial vorticity field with a planetary vorticity term, and find a change of statistical equilibria from quadrupole states to zonally symmetric states as the angular velocity of the sphere increases. The quadrupole statistical equilibria show nearly linear relations between the macroscopic vorticity and the macroscopic stream function, implying that higher-order Casimir invariants are virtually ineffective even when all Casimir invariants are considered. The discrepancy between the equilibria and the time integration results emphasizes the importance of mixing barriers, which prevent the relaxation of the evolving vorticity field to the statistical equilibria and allow the point-vortex-like dynamics of coherent vortices to persist.
- [28] arXiv:2606.27833 [pdf, html, other]
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Title: Collisionless dynamo seeds from phase mixing-induced electron slippageComments: 3 figuresSubjects: Plasma Physics (physics.plasm-ph)
Magnetic fields permeating the Universe on the largest astrophysical scales are thought to result from dynamo amplification in weakly collisional turbulence, but the origin of the seed fields remains an open problem of cosmic magnetogenesis. We identify a kinetic mechanism for magnetic-field generation in initially unmagnetized, collisionless plasmas, arising from phase-mixing-induced braking of spatially varying electron flows. Using analytical theory, fully kinetic Vlasov simulations, and turbulent scaling arguments, we show that this process generates coherent magnetic seed fields on scales far larger than the characteristic kinetic scales of the plasma, with strengths comparable to or exceeding classical Biermann battery estimates. The mechanism requires neither a finite initial magnetic field nor misaligned thermodynamic gradients and occurs naturally in electron--ion plasmas.
- [29] arXiv:2606.27860 [pdf, html, other]
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Title: Extracting behavioural properties from face-to-face interactions temporal networks: a measure of egonet persistencyComments: 23 pages, 11 figures, 6 tablesSubjects: Physics and Society (physics.soc-ph); Computational Physics (physics.comp-ph)
Understanding how individuals repeat social interactions over time is a central problem in the analysis of temporal networks. In social systems, repeated interactions shape processes such as information diffusion, collective coordination, and the emergence of social structure. Existing measures of egonet persistence often conflate genuine behavioural regularities with structural effects such as node degree, making it difficult to distinguish meaningful temporal correlations from random mixing.
In this work, we introduce the Neighbourhood Persistency Criterion (NPC), a statistically grounded framework for quantifying egonet persistence across time. NPC combines classical similarity measures with tailored null models controlling for network topology and interaction weights.
We apply this framework to high temporal resolution face-to-face interaction networks collected at four Computational Social Science conferences using the SocioPatterns platform. Our results reveal a common behavioural structure across events, characterised by an exploration$\unicode{x2013}$exploitation trade-off in social interactions. While many individuals alternate between both strategies, others exhibit stable interaction patterns throughout the event. Importantly, these behaviours show little systematic association with socio-demographic attributes, suggesting that interaction strategies are shaped primarily by contextual factors rather than stable individual traits. NPC thus provides a flexible and interpretable tool for studying egonet persistence in temporal networks and social systems. - [30] arXiv:2606.27873 [pdf, html, other]
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Title: Ocean-atmosphere interaction at the Gulf Stream sea surface temperature front: variability and impacts on midlatitude atmospheric circulationComments: PhD Thesis. Supervisor: Alessio Bellucci. Co-Supervisors: Panos J. Athanasiadis, Paolo RuggieriSubjects: Atmospheric and Oceanic Physics (physics.ao-ph)
Sea surface temperature (SST) gradients associated with western boundary currents affect the atmospheric circulation across a range of spatial and temporal scales. Yet, several aspects of ocean-atmosphere interactions linked to oceanic fronts remain unclear. This PhD thesis analyses such interactions for the Gulf Stream SST front (GSF). The first part assesses the atmospheric response to the interannual GSF meridional shifts and its dependence on model horizontal resolution, using ERA5 reanalysis and atmosphere-only simulations forced by observed SST. Results show that the response is strongly resolution dependent, with only simulations finer than 50km resembling observed anomalies. Locally, diabatic heating near the GSF is mainly balanced by vertical motion and transient eddy heat transport. At large-scale, the GSF shifts is associated with a homo-directional shift in the North Atlantic eddy-driven jet and storm track, mediated by changes in low-level baroclinicity. The second part assesses the North Atlantic Oscillation (NAO)-GSF interaction and the mechanisms through which the NAO forces the GSF shifts on decadal timescale, using atmosphere and ocean reanalyses. The NAO and GSF covary on decadal timescales only during 1972-2018. This non-stationarity is also reflected in their lead-lag relationship: the NAO leads the GSF shifts by 3 years during 1972-1990 and by 2 years during 1990-2018. The lag is interpreted as the joint effect of the fast response of wind-driven oceanic circulation, the lagged response of deep oceanic circulation, and the propagation of Rossby waves. However, Rossby wave propagation is evident only before 1990, suggesting that its non-stationarity may explain the different NAO-GSF time lag before and after 1990. Overall, the thesis improves understanding of GSF variability and its role in North Atlantic and extratropical climate variability.
- [31] arXiv:2606.27889 [pdf, html, other]
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Title: Electrons with Anomalous Energy Generated in Gas-Filled and Vacuum DiodesVictor F. Tarasenko, Vasily Yu. Kozhevnikov, Andrey V. Kozyrev, Evgenii Kh. Baksht, Maxim S. VorobyovComments: 16 pages, 6 figuresSubjects: Plasma Physics (physics.plasm-ph); Accelerator Physics (physics.acc-ph)
It is shown that, when high-voltage pulses (with a voltage amplitude exceeding 100 kV in centimeter gaps) with a leading edge duration of 1 ns or shorter are applied to gas-filled and vacuum electric discharge diodes, electrons with kinetic energies nominally exceeding the amplitude of the applied voltage are detected. In the experiments, electron beam attenuation curves were measured in absorbers consisting of Al foil of varying thicknesses. These curves were used to reconstruct the electron beam energy spectrum by regularizing the solution of an integral equation based on deep machine learning. The obtained spectra contain electrons with anomalously high energies, the proportion of which, depending on the conditions, can reach 25 percent. A control experiment with a long voltage pulse on a large-area vacuum diode (voltage 150 kV, pulse duration 35 microseconds, vacuum gap 12 cm, electrode area 75 x 15 cm2) showed that the proportion of electrons with anomalous energies is less than 0.2 percent. Experiments have shown that the main mechanism for generating electrons with anomalous energy is the spatio-temporal synchronism of the motion of fast electrons in the enhanced field formed in the gap by space charge.
- [32] arXiv:2606.27891 [pdf, html, other]
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Title: Vibrational high-harmonics and period-doubling bifurcation probed by time-resolved electron diffractionSubjects: Optics (physics.optics); Instrumentation and Detectors (physics.ins-det)
Nanoscale mechanical oscillators exhibit a plethora of nonlinear phenomena with promising applications for the sensing and clocking of processes down to atomic length scales. Oscillator dynamics are typically probed by electrical or optical means, providing only limited access to the spatial profile of the oscillator motion. Here, we introduce event-based convergent beam electron diffraction for the spatio-temporal mapping of nanoscale mechanical resonators in ultrafast transmission electron microscopy. Employing an optically driven silicon membrane resonator at various driving strengths, we gain access to nonlinear processes with increasing complexity, ranging from a simple Duffing behavior to nonlinear multimode coupling and period-doubling bifurcations. The time-resolved diffraction probing approach supports a spatial resolution down to a few nanometers and a temporal resolution of 5 ns and provides quantitative information on the local membrane bending. Because the diffraction signal responds to local displacement gradients, which become more pronounced as resonators shrink, this approach offers a route toward probing nonlinear nanomechanics at the atomic scale.
- [33] arXiv:2606.27895 [pdf, html, other]
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Title: Mosaic: A Benchmark Suite for Differentiable Physics SolversComments: 32 pages, 24 figures, 3 tables. Code available at this https URLSubjects: Computational Physics (physics.comp-ph); Machine Learning (cs.LG)
Differentiable partial differential equation (PDE) solvers underpin solver-in-the-loop ML training, gradient-based optimal control, and inverse problems, yet the practical cost of obtaining correct, usable gradients from a given solver on a given problem is largely undocumented. Integration effort, computational cost, gradient accuracy, and numerical conditioning vary widely across solvers and are discoverable only by trial and error. We introduce Mosaic, an extensible benchmarking framework for differentiable PDE solvers that standardizes access to solver gradients. Each solver is packaged as a containerized component (Tesseract) exposing a uniform gradient API regardless of language or automatic differentiation (AD) strategy, enabling researchers to evaluate, compare, and build on non-trivial physical solvers. Our evaluation of 14 solvers across fluid dynamics, structural mechanics, and heat transfer demonstrates that the benchmark surfaces practically relevant differences: order-of-magnitude variation in computational cost and Jacobian conditioning, alongside structural incompatibilities that eliminate solvers from realistic tasks entirely. Despite this variation, all solvers that produce gradients converge to similar optima, indicating that the practical barriers are memory limits, numerical stability, and setup compatibility rather than gradient accuracy alone. Mosaic is open-source and available at this https URL.
- [34] arXiv:2606.27911 [pdf, other]
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Title: Quantum frequency comb with pump-selectable bin pairing and extraction-aware loading in a lithium niobate microresonatorMohamad Reza Nurrahman (1), Hyeon Hwang (1), Nuri Han (1), Guhwan Kim (2), Hong-Seok Kim (2), Kiwon Moon (2), Jung Jin Ju (2), Hansuek Lee (1), Min-Kyo Seo (1) ((1) Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon, Republic of Korea, (2) Quantum Optics Research Section, Electronics and Telecommunications Research Institute, Daejeon, Republic of Korea)Comments: Mohamad Reza Nurrahman and Hyeon Hwang contributed equally to this work. Correspondence should be addressed to Hyeon Hwang (hyeon_hwang@kaist.this http URL) and Min-Kyo Seo (minkyo_seo@kaist.this http URL)Subjects: Optics (physics.optics)
Integrated quantum photonics requires bright, high-fidelity photon-pair sources capable of spectral multiplexing, correlation control, and circuit-compatible extraction. Cavity-enhanced spontaneous parametric down-conversion (SPDC) enhances pair generation, but triply resonant operation imposes stringent pump-signal-idler spectral-alignment constraints. Moreover, the trade-off between intrinsic generation and coincidence-to-accidental ratio (CAR) does not capture the usable output flux, which depends on photon extraction. Here, we demonstrate a single-pass-pumped, resonator-enhanced quantum frequency comb (QFC) source based on a periodically poled lithium niobate photonic-crystal Fabry-P$é$rot microresonator. The device yields intrinsic and loaded brightnesses of 69.9 and 1.88 MHz/$\mu$W, respectively, and a maximum CAR of 16,000. Frequency-resolved measurements reveal 461 cavity-defined bins spanning 1495-1570 nm, and loaded spectral brightness approaching 4.29$\times$10${}^9$ pairs/(s$\cdot$mW$\cdot$nm). In particular, tuning the single-pass pump deterministically selects correlated frequency-bin pairings within the fixed QFC grid while preserving brightness and pairwise coincidence rates. We further separate intrinsic generation from output photon-pair flux, revealing the loaded-brightness-CAR relation. Together, pump-selectable bin pairing and extraction-aware loading point to tailored SPDC QFCs as chip-integrated nonclassical light resources for multiphoton-interference quantum simulation and programmable frequency-bin quantum information processing.
- [35] arXiv:2606.27920 [pdf, html, other]
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Title: Unidirectional Guided Resonances Enabled by Competing Fourier Harmonics near the Fourth Stop BandSubjects: Optics (physics.optics)
Unidirectional guided resonances (UGRs) have attracted considerable attention owing to their remarkable ability to radiate exclusively in one direction from single-layer planar photonic lattices without metallic components. Conventionally, UGRs have been understood to require either broken in-plane $C_2$ symmetry or interband coupling between distinct modes. Here, a new mechanism for realizing UGRs is presented, in which out-of-plane radiation near the fourth stop band is mediated by two distinct channels associated with the first and second Fourier harmonics. When the radiation components from the first and second Fourier harmonics cancel each other out in both the upward and downward directions, nonradiative bound states in the continuum emerge. By contrast, UGRs arise when such cancellation occurs only in one direction. By tuning the lattice parameters, the positions of these UGRs can be controlled, allowing them to merge at the $\Gamma$ point. The two-channel radiation-cancellation model enables UGRs without relying on in-plane symmetry breaking or interband coupling, thereby relaxing lithographic constraints and simplifying device design. It also provides a useful framework for controlling topological singular states in higher-order photonic bands.
- [36] arXiv:2606.27921 [pdf, html, other]
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Title: Effect of an aligned current on the stability of oscillatory incompressible flow past a circular cylinderComments: 28 pages, 26 figures, submitted to JFMSubjects: Fluid Dynamics (physics.flu-dyn)
The stability of incompressible flow past a circular cylinder under collinear steady and oscillatory forcing is investigated within a two-dimensional Floquet framework. The flow is parameterised by the Keulegan-Carpenter number $KC \in [4,12]$, the steady-to-oscillatory velocity ratio $m \in [0,1]$, and the oscillatory Reynolds number $Re_m \in [20,100]$. The loci of the leading Floquet multipliers, and hence case-specific bifurcation modes, are examined by progressively reducing $Re_m$ to subcritical values for prescribed $m$. A steady current with $m > 0.5$ gives rise to a period-doubling subharmonic bifurcation that does not occur in purely oscillatory flow, where only synchronous and quasi-periodic modes arise. For $Re_m = 100$, three key features are discernible. First, the neutral stability curve in $(KC,m)$ space is strongly non-monotonic in $m$, separating intrinsically stable regions from those with single unstable modes; a sub-region of striking mode re-stabilisation appears beyond $m \approx 0.9$, where the flow recovers a $Z_2$-symmetric state at peak Reynolds number $\approx 190$, despite the steady and oscillatory components each being individually unstable. Second, a distinct regime supports the coexistence of two unstable modes of different types. Third, complementary direct numerical simulations show that, for a single unstable mode, the linear analysis successfully predicts the saturated nonlinear state even when $Re_m = 100$ substantially exceeds the critical Reynolds number, whereas under mode coexistence the quasi-periodic attractor tends to dominate the developed dynamics.
- [37] arXiv:2606.27937 [pdf, html, other]
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Title: Preferentiality and bandwidth drive tie activity in online and offline ego networksGamal Adel, Shrichand Bhuria, Alessandro Catalano, Liber Dorizzi, Leonardo Federici, Theodora Moldovan, Berné Nortier, Chara Deanna Punzal, Giulia de Meijere, Gerardo IñiguezComments: 25 pages, 10 figures, Complexity72h WorkshopSubjects: Physics and Society (physics.soc-ph)
Ego networks capture the variety of structural patterns in the social interactions of individuals. Recently it has been shown that ego networks in online settings display universal patterns of tie strength distributions, but it is unclear how constraints such as spatial proximity and bounded social bandwidth affect such generic behaviour in offline settings. Here, we analyse the time evolution of interaction activity in ego networks constructed from offline face-to-face and colocation data, compare them to online communication networks, and explore simple cumulative advantage models that capture the varying preferentiality of individuals for specific social ties. We find that patterns of preferentiality at the population level are similar for online and face-to-face networks, but not for colocation data, suggesting that the latter is a poor proxy of social network structure. We also provide evidence that empirical ego networks exhibit a bandwidth in the way communication events are allocated across connections. A model implementing this notion uncovers evidence of universal scaling between the tie preferentiality and bandwidth of individuals, common to all online and offline systems explored. Our findings strengthen our understanding of the fundamental mechanisms governing human communication and help disentangle the internal and external factors shaping tie evolution across social contexts.
- [38] arXiv:2606.27938 [pdf, html, other]
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Title: Students using GenAI lag behind in problem-solving competence: an agent-based study of classroom networksLorenzo Betti, Iacopo Caporossi, Carsten Källner, Karolina Levanaitė, Chenyu Li, Xuan-Chen Liu, Giulia Lorenzini, Vittoria Socci, Michele Re Fiorentin, Ilaria Stanzani, Marta BarattoComments: 21 pages, 16 figures, This work is the output of the workshop Complexity72h by Complexity Next Gen, held at Northeastern University London, London, UK, 22-26 June 2026. this http URLSubjects: Physics and Society (physics.soc-ph)
The development of problem-solving competence (PSC) among high school students is foundational for preparing resilient and adaptive citizens. Generative artificial intelligence (GenAI) can support this process, but it may also encourage students to offload part of the cognitive work that is necessary for deep learning. While the individual effects of GenAI use are increasingly studied, its collective consequences for competence development within classroom environments remain underexplored. In this study, we use an agent-based model to simulate the evolution of PSC in a high school physics classroom, where students complete tasks individually, in collaboration with peers, or with the support of GenAI. By comparing classrooms with and without access to GenAI across different peer-network structures, we show that GenAI use can diminish competence development and increase the share of students remaining in lower competence tiers. These results suggest that the educational impact of GenAI should be assessed not only through individual learning outcomes but also through its effects on collective competence dynamics.
- [39] arXiv:2606.27956 [pdf, html, other]
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Title: Linking the "inner" and "outer" self to mental health and brain networksCosimo Agostinelli, Ivan Casanovas, Lochan Chaudhari, Arda Ergin, Pablo Estévez-Gutiérrez, Akanksha Gupta, Juliane T. Moraes, Mario Edoardo Pandolfo, Carlos Gershenson, Haily Merritt, Andreia Sofia TeixeiraComments: This work is the output of the workshop Complexity72h by Complexity Next Gen, held at Northeastern University London, London, UK, 22-26 June 2026Subjects: Physics and Society (physics.soc-ph)
How are psychosocial profiles, mental health, and brain functional connectivity related? Studies have been dedicated to unraveling the associations of social support perception and neural functional connectivity. Additionally, personality traits have been explored by examining brain networks. Research on mental health has been developed using a broad range of methods and different approaches. However, little attention has been devoted to understanding how personality traits and social variables are related, and to what extent these components are reflected in brain functional connectivity and mental health outcomes. In this work, we aim to address these complex relations by using data from the Human Connectome Project, both from surveys and resting-state fMRI. The survey data includes personality traits measures and self-reported social support-related variables, which we will refer to as inner- and outer-self, respectively. It also includes data on mental health outcomes. Using z-score standardized measures, we analyze correlation matrices to evaluate the association between the inner- and outer-self domains. Our results show that the social indicators are more evidently grouped by impact on social experience than by the duality of inner-outer selves. Using a $k$-means clustering algorithm, we separate individuals into two groups according to social profiles. When confronting these results with the mental health outcomes, we show that the more socially desirable cluster exhibited a higher score on positive aspects such as life satisfaction and purpose in life. In the functional brain connectivity, we observe that the cluster with a more socially beneficial profile exhibits lower interconnectivity, especially in the default mode network. The pipeline we present uses a combined analysis of both fMRI and psychosocial variables, which could open the path for more extensive analysis.
- [40] arXiv:2606.27957 [pdf, html, other]
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Title: From streaks to synergies: A multi-scale analysis of performance and scoring in the NBAMalvina Bozhidarova, Yanpei Cai, Ricardo M.S. Carvalho, Daniele Cirulli, Quentin Dehaene, Martin Diaz, Alexandra Krasnokutskaya, Bernardo Pereira, Onkar Sadekar, Federico BattistonComments: Prepared at the Complexity72h workshop London, June 2026Subjects: Physics and Society (physics.soc-ph)
Modern play-by-play data make it possible to test long-standing intuitions about basketball with the same statistical rigour now routinely applied to other professional sports. Using play-by-play data from 7,054 regular-season and 504 playoff NBA games spanning the 2020-2025 seasons, we provide quantitative insights into scoring patterns and the performance of individual players and teams through methods from statistics, network science, and complexity science. Our findings offer an evidence-based perspective on in-season and in-game performance that can inform coaching strategies, player evaluation, and tactical decision-making.
- [41] arXiv:2606.27968 [pdf, html, other]
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Title: SimPol: Simulating polarisation in political belief networks in European countriesIsabela Burattini Freire, Hongryol Cha, Irina Epure, Sara Filippini, Karan K.H. Manjunatha, Chethan Kavaraganahalli Prasanna, Ivan Samoylenko, Niels Van Santen, Adarsh Prabhakaran, Guillermo Romero MorenoSubjects: Physics and Society (physics.soc-ph)
Here we combine empirical network analysis with agent-based modelling to understand how different ways of structuring belief systems may affect the polarisation drive, and how the diversity of belief systems in Europe may result in different polarisation trajectories. Using the 2016 European Social Survey, we infer belief networks across 23 European countries via a Bayesian algorithm, revealing that belief systems are predominantly organised around immigration, LGBT rights, and economic interventionism, reflecting the influence of populist discourse across the continent. We further verify a Western-Eastern divide across the national belief networks: in Western European countries, left-right self-identification is a more reliable predictor of broader belief alignment, whereas in Eastern Europe this relationship breaks down. By applying these empirical belief networks into a sociologically grounded agent-based model, we further show that polarisation is amplified by high individual belief rigidity and low susceptibility to social influence, and that cross-country differences in polarisation levels mirror the same geographic divide observed in belief network topology. These findings establish belief networks topologies as a structural driver of political polarisation, with implications for understanding and anticipating polarisation dynamics across diverse European contexts. We find that populations are not polarised when little attention is placed on maintaining internal coherence and polarisation levels are moderate when high attention is placed in both keeping internal coherence and agreement in beliefs with others.
- [42] arXiv:2606.27986 [pdf, html, other]
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Title: Flow dynamics in a wavy channel filled with anisotropic porous material under the effect of wall slipSubjects: Fluid Dynamics (physics.flu-dyn)
In this study, a theoretical and graphical analysis is conducted to examine the effects of wall-velocity slip, anisotropic ratio, and porosity parameter on a two-dimensional, viscous, laminar, and incompressible flow through a wavy channel filled with anisotropic porous media. The flow is assumed to be steady and symmetric, with a constant volumetric flow rate imposed along the channel walls. The governing equations are described using the Darcy-Brinman model coupled with the continuity equation, while the tangential velocity at the wavy boundaries is represented through Navier slip conditions. An analytical solution is obtained using a perturbation approach under physically consistent boundary conditions. The effects of key parameters, including anisotropic ratio, Darcy number, and slip parameter, on flow characteristics such as axial velocity, pressure gradient, shear stress, and streamline patterns are examined in detail and presented graphically. The results indicate that wall velocity slip significantly reduces flow reversal, enhances near-wall velocity, and decreases the center-line velocity. For a fixed non-zero slip, a decrease in the Darcy number leads to a pronounced modification in the velocity profile, while increased slip further strengthens near-wall flow and weakens the core flow. Additionally, the streamline analysis reveals that velocity slip plays an important role in controlling flow separation near the crest of the wavy wall. In the case of isotropic porous media with a large amplitude wavy channel, flow separation can also be effectively regulated. Overall, the study demonstrates that velocity slip provides a powerful mechanism for controlling flow behavior by altering the shear distribution within the perturbed flow, with potential applications in technological, geophysical, and biophysical transport systems.
- [43] arXiv:2606.28001 [pdf, html, other]
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Title: Diagnosing Ghost Bunches with the Upstream Extinction Monitor in the Mu2e ExperimentR. Hensley (1), E. Prebys (1), A. Gaponenko (2) ((1) University of California, Davis, Davis, United States, (2) Fermi National Accelerator Laboratory, Batavia, United States)Comments: 16th International Partical Accelerator Conference (IPAC'25)Subjects: Accelerator Physics (physics.acc-ph)
The Mu2e experiment has a stringent requirement for extinction of the pulsed proton beam, referring to the elimination of particles between proton bunches to a relative level of 10$^-10$, which means a single out-of-time particle in the inter-pulse gaps for every 250 complete proton pulses. As the construction of the Mu2e experiment nears completion, it is crucially important to make an early measurement of the beam extinction in its current condition. Hence the upstream extinction monitor was constructed and operated to probe for problems in the proton pulse structure or a higher than expected incidence rate of out-of-time particles. The analysis in this work comes from data taken in March 2026. The long data run showed a significant presence of out-of-time particles from ghost bunches in the Delivery Ring approximately 388 ns after the centers of the main proton pulses. These are hypothesized to be the result of a combination of a RF frequency mismatch, particle space charge, and machine impedance during the rebunching sequence in the Recycler Ring, which can lead to particles leaking into adjacent buckets, but further studies and simulations are needed to confirm this
- [44] arXiv:2606.28018 [pdf, other]
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Title: Effects of thermochemical modelling on a hypersonic shock-wave/turbulent boundary-layer interactionSubjects: Fluid Dynamics (physics.flu-dyn)
Thermochemical non-equilibrium can alter the structure, loads, and time scales of hypersonic shock-wave/turbulent boundary-layer interactions, yet its role in fully turbulent configurations remains largely unquantified. The present work addresses this issue by performing three direct numerical simulations of an oblique shock impinging on a turbulent high-enthalpy boundary layer at edge Mach number $M_e=6.4$ and stagnation enthalpy $H_e=16.9$ MJ/kg. The simulations share identical geometry and freestream conditions, but employ a hierarchy of progressively simplified thermochemical descriptions: a finite-rate reactive case, a single-species thermally perfect gas model, and a single-species calorically perfect model. The reactive simulation shows that the shock-induced temperature rise substantially enhances chemical activity relative to the incoming boundary layer, with peak concentrations of dissociation products attained downstream of the interaction. Thus, the thermal and chemical responses are not synchronised: the composition lags the rapid thermal forcing imposed by the shock system, and turbulent Damköhler numbers reach values of order unity within the recirculation region, indicating non-negligible turbulence-chemistry interaction. The comparison among the three models shows that thermally and calorically perfect descriptions yield similar predictions, whereas finite-rate chemistry produces systematic differences: a smaller separation bubble, lower post-interaction wall heat flux, lower mean and fluctuating temperatures, and a less inclined reflected shock. In the present regime, the dominant modelling distinction is therefore between frozen and chemically reacting descriptions, with caloric-model effects playing only a secondary role.
- [45] arXiv:2606.28021 [pdf, html, other]
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Title: Multiscale Cavitation Sub-Grid Modeling via Population Balances as Linear Stochastic ProcessSubjects: Fluid Dynamics (physics.flu-dyn)
A multiscale sub-grid cavitation model is developed in which the bubble size distribution evolves as a linear stochastic process in radius space. Starting from the integrated Rayleigh--Plesset equation, the population balance is recast as a hyperbolic transport equation for the number density per radius, whose method-of-characteristics solution, projected onto a discrete histogram basis, yields a column-stochastic Markov chain governing the bubble counts per size bin. The transition matrix factors into a precomputable, mesh-only geometric part and a local, pressure-dependent shift, isolating the coupling to the surrounding flow into a single dimensionless vector per cell. The framework recovers classical homogeneous-mixture cavitation closures in the limit of a single representative scale.
- [46] arXiv:2606.28022 [pdf, html, other]
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Title: FMO-xTB: Fragment molecular orbital method with GFN1-xTB for large-scale quantum-mechanical simulationsComments: 23 pages, 6 figuresSubjects: Chemical Physics (physics.chem-ph)
We present the fragment molecular orbital method (FMO) combined with the GFN1-xTB extended tight-binding approach (FMO-xTB) for efficient quantum-mechanical calculations of large molecular systems. Both the two-body (FMO2) and three-body (FMO3) expansions are formulated, and fully analytic energy gradients including the response contribution from the self-consistent embedding potential are derived and implemented. The FMO-xTB method inherits the broad element coverage of GFN1-xTB, which employs element-specific rather than atom-pair-specific parameters and is parameterized for all spd-block elements up to radon(Z = 86), representing a significant practical advantage over FMO- DFTB approaches. The accuracy of FMO-xTB is systematically benchmarked against non-fragmented xTB calculations for water clusters, anthracene aggregates, and pentacene supercells. FMO3-xTB reproduces the reference energies with deviations on the order of 10^-4 Hartree for organic semiconductor systems. The covalent bond fragmentation capability using the hybrid orbital projection (HOP) boundary treatment is also implemented with fully analytic gradients and validated for polyalanine alpha-helices and B-DNA double helices, yielding FMO3-xTB energy deviations on the order of 10^-6 Hartree for polyalanine and in the millihartree range for B-DNA. Near-linear scaling is achieved with effective scaling exponents between b= 1.06 and b= 1.28, compared to cubic scaling for non-fragmented xTB. Parallelization over multiple CPU cores yields significant speed ups, and a complete energy and gradient evaluation of a pentacene supercell containing 23760 atoms is feasible within minutes on a single computing node, enabling routine molecular dynamics simulations of systems with tens of thousands of atoms. The method is implemented in the DIALECT software package.
- [47] arXiv:2606.28025 [pdf, html, other]
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Title: Indecision and accuracy under social information across groups sizesComments: 20 pages Main document, 18 pages Supplementary Material (together making 38 pages total). Main document has 9 Figures (20 Subfigures), Supplementary has 13 Figures (70 Subfigures), so total of 22 Figures (90 Subfigures)Subjects: Physics and Society (physics.soc-ph)
Observing the decisions and actions of others provides social information that can inform decisions such as whether to follow. We consider a model where agents simultaneously gather stochastic private information, each deciding once sufficiently confident. Observed decisions and indecision provide social information that triggers discrete waves of collective response: a first decision causes others to update and potentially follow, whose decisions in turn provide further social information, generating successive waves. We explore this model across a range of group sizes and report three main findings. First, social information leads to faster and more accurate decisions than individual decision-making, but agent-level accuracy is maximised at a finite optimal group size. This contrasts with the accuracy of the majority choice, which increases monotonically with the number of agents. Second, waves frequently fail to resolve collective indecision, particularly for smaller groups and when the first decision is incorrect, leaving a subgroup of agents unconvinced. Third, these remaining undecided agents are systematically biased and make less accurate subsequent decisions, with this inaccuracy growing with group size.
- [48] arXiv:2606.28038 [pdf, html, other]
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Title: Broadband on-chip Half Maxwell FisheyeXin Zheng, Quan Yue, Jean-René Coudevylle, Aziz Benamrouche, Ségolène Callard, Anatole Lupu, Éric AkmansoyComments: 26 pages, 14 figuresSubjects: Optics (physics.optics)
In this article, we report on the design and the experimental evidence of a Half Maxwell Fish Eye (HMFE), for Silicon Photonics and working at telecommunication wavelength. It is designed by implementing a Graded Photonic Crystal operating in the non-resonant metamaterial regime. The results of 3D Finite-Difference Time-Domain simulations (FDTD) show an excellent broadband focusing capacity. It has been urther fabricated via the Silicon On Insulator (SOI) platform for its compatibility with CMOS technology. Experimentally, its performances are firstly investigated by the means of a fan-shaped set output waveguides. Next, Scanning Near-Field Optical Microscopy (SNOM) characterisation confirms the wavefront curving inside the HMFE lens. Quantitative analysis of the SNOM results demonstrates its excellent focusing performances: the Full Width Half Maximum (FWHM) is $0.466\lambda_0$ at $\lambda_0=1550$nm, while the thickness of the lens is $3.18\lambda_0$.
- [49] arXiv:2606.28043 [pdf, other]
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Title: On the Relationship Between Plasma and Tritium Fuel Cycle Through Matter Injection and Particle ExhaustSubjects: Plasma Physics (physics.plasm-ph)
This work identifies an inconsistency between plasma operating scenarios and tritium fuel cycle (TFC) requirements, calling for a re-examination of the traditional reactor-led design approach. The key point is simple: in current TFC architectures, fuel puffing must contain tritium. Moscheni et al. (2026 Nucl. Fusion 66 026008) investigated fuel puffing rates in detached operation. Expanding that database, puffing is shown to exceed core fuelling by about an order of magnitude, from present-day tokamaks to next-step stellarators. Though not unknown in the plasma community, TFC models instead assumed core fuelling to dominate. The implications are severe. In recent TFC architectures, direct internal recycling (DIR) is intended to minimise tritium inventory, but assumes near-50:50 D:T composition. This assumption may become self-defeating: a substantial fraction of the puffed fuel must be tritium. Tritium inventory, doubling time, required breeding ratio, and pump sizing therefore become critical once puffing is properly accounted for. Mitigation is assessed by extending the models of Meschini et al. (2023 Nucl. Fusion 63 126005). For a notional plant, realistic TFC requirements can be met with D-rich, T-lean puffing, at the cost of about 10% lower fusion power. Alternatively, for near-50:50 D:T puffing, reduced fuel puffing with stronger impurity seeding can maintain detachment while alleviating TFC constraints, albeit with higher core contamination. Combined use of these strategies enables scenarios that minimise tritium inventory and throughput while balancing competing requirements. Ultimately, these results place renewed emphasis on the TFC as a central element of reactor design. A viable fusion reactor requires joint optimisation of core plasma, edge plasma, and TFC, implying unavoidable trade-offs across all three.
- [50] arXiv:2606.28075 [pdf, html, other]
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Title: Active diffusion enhances plankton carbon capture and phycosphere radiusSubjects: Biological Physics (physics.bio-ph)
Plankton fix about 40 gigatons of carbon annually, using photosynthesis to convert $\text{CO}_2$ into $\text{O}_2$ and carbohydrates. These solutes are exchanged with the ocean in a diffusive boundary layer around the organism called the phycosphere. Here, we study how organisms can increase their carbon influx and outflux by actively mixing the surrounding fluid. By developing exact analytical expressions validated by stochastic simulations, we determine the enhanced diffusivity of phycosphere particles as a function of mixing activity, and their resulting fluxes and concentration fields. Hence, we find that plankton can significantly increase their uptake and photosynthetic turnover. Moreover, we find that the phycosphere radius is enlarged both by increased metabolism and by increased diffusive transport further from the organism. These results provide new biophysical insights into marine microbial ecology, with important implications for global carbon capture and climate change.
- [51] arXiv:2606.28119 [pdf, other]
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Title: Physics-constrained neural networks for surrogate modeling of lossless periodic structuresComments: 10 pages, 5 figures. Supplementary Document 1 and Supplement 2 (Visualization 1) are provided as ancillary filesSubjects: Optics (physics.optics); Machine Learning (cs.LG)
We introduce a physics-constrained neural network (PCNN) for the rapid prediction of rigorous coupled-wave analysis (RCWA) outputs in the form of Jones matrices. Starting from energy conservation in lossless layered periodic structures, we use the fact that RCWA outputs lie on a Stiefel manifold. This energy constraint is enforced as a hard condition by projecting onto the manifold using differentiable symmetric orthogonalization. The resulting surrogate enforces energy conservation by construction while preserving differentiability for gradient-based inverse design. The performance and generality of the proposed approach are demonstrated through the inverse design of a diffractive waveguide combiner for augmented reality glasses.
- [52] arXiv:2606.28137 [pdf, other]
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Title: A single platform with van der Pauw geometry for measurement of Seebeck coefficient, resistivity, and Hall effect of thin filmsNiraj Kumar Singh, Martin Falk, Per-Anton Schön Wallander, Per Sandström, Per Eklund, Arnaud le FebvrierSubjects: Instrumentation and Detectors (physics.ins-det); Materials Science (cond-mat.mtrl-sci)
A modular thermoelectric properties measurement setup in van der Pauw configuration was developed for a straightforward and simultaneous measurement of electrical resistivity and Seebeck coefficient in an extensive temperature range of 25°C - 600°C and can also perform Hall measurements at room temperature. The setup is optimized for accurate measurement of voltages and temperatures gradients by minimizing possible errors from offset voltages, wire contributions and thermal contact resistances which helps getting reliable data. The setup is user friendly, and the measurements are fully automated and controlled using a LabVIEW program. The detachable modules make this setup quite versatile and provide an all-in-one (except thermal conductivity) solution for thermoelectric measurements.
- [53] arXiv:2606.28154 [pdf, html, other]
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Title: A Weakly Nonlinear Theory of Zonal-Flow Forcing in Gyrokinetic TurbulenceComments: 33 pages, 9 figuresSubjects: Plasma Physics (physics.plasm-ph)
The forced generation of zonal flows by microinstability-driven turbulence is investigated within the framework of local gyrokinetic theory far from marginality. We use a numerically and physically informed three-wave truncation scheme, which allows the prediction of the zonal-flow k_{\psi}-spectrum during the early phase of nonlinear gyrokinetic simulations. The model reproduces the known 2-\gamma growth rate resulting from nonlinear beating of linearly unstable primary modes, in line with previous results, without any marginal stability point. The phase-space structure of such zonal flow is strongly constrained by that of the driving fluctuations, which is essential to understand its behaviour in the region of validity. It is shown that this leads to an enhanced residual spectrum compared to the classic Rosenbluth-Hinton calculation.
- [54] arXiv:2606.28165 [pdf, html, other]
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Title: Observations and empirical functions for the ocean surface wave spectrumComments: 19 pages, 7 figuresSubjects: Atmospheric and Oceanic Physics (physics.ao-ph); Fluid Dynamics (physics.flu-dyn)
Accurate parameterizations of ocean wave spectra are necessary in a wide array of disciplines including coastal, ocean, and naval engineering as well as in the study of wave interactions and ocean-atmosphere momentum flux. Many such applications use spectrum parameterizations based on temporal data collected well over a half century ago. The development of spatial wave measurement techniques that can accurately capture a larger range of scales allows us to revisit the question of how best to represent an ocean wave spectrum in a variety of ocean wave conditions. We discuss two commonly used wave spectrum parameterizations through a comparison to data collected in field campaigns studying fetch-limited, fully-developed, and mixed sea conditions. We discuss a spectrum parameterization for fully-developed seas that has a $k^{-2.5}$ (or $\omega^{-4}$) dependence on the wavenumber (or angular frequency) in the tail as opposed to the $k^{-3}$ (or $\omega^{-5}$) dependence seen in other frequently-used parameterizations. With knowledge of the peak wavenumber $k_p$ and significant wave height $H_s$, alongside the wind speed, fully-developed conditions can be well-represented. We then compare the impact of using different wave spectrum parameterizations through a Large Eddy Simulation (LES) study of Marine Atmospheric Boundary Layers (MABLs) over the sea surface and find that changing the parameterization used results in variations in the equivalent roughness akin to significant changes in wave conditions.
- [55] arXiv:2606.28176 [pdf, html, other]
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Title: Direct Observation of X-ray Double-Slit Interference in Momentum SpaceSubjects: Optics (physics.optics); Applied Physics (physics.app-ph)
Young's double-slit experiment is conventionally deemed a spatial phenomenon emerging from free-space transport. In this Letter, we invert this perspective to demonstrate that Young's interference can be accessed directly as a pure momentum-space observable. Using a perfect-crystal diffraction to project the field's reciprocal-space profile immediately downstream of the aperture, we resolve the complete hard X-ray double-slit fringe structure without any propagation arm, focusing optics, or imaging detector. This direct capture of the field's invariant momentum marginal establishes a compact, lensless, and propagation-free approach to coherence diagnostics, proving that the fundamental physics of wave interference can be detached from real-space propagation.
- [56] arXiv:2606.28260 [pdf, html, other]
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Title: The Allee Effect in Compressible FlowsSubjects: Biological Physics (physics.bio-ph); Soft Condensed Matter (cond-mat.soft); Fluid Dynamics (physics.flu-dyn)
Microbes in marine environments are often confined to thin near-surface layers while being advected by turbulent flows. Because such constrained advection generates an effectively compressible flow, reproduction and transport interact in a nontrivial way. Here, we focus on populations whose growth is governed by an Allee effect and show that sinks and sources, generated by the compressible flow, have dramatic consequences for the survival of such species. We derive analytical expressions for the carrying capacity as a function of the Allee strength in the limit of small and large Damköhler number, which measures the product of the large eddy turnover time and the organism growth rate. Numerical simulations reveal how these two limits connect. In the limit of small Damköhler number, we find a maximal Allee strength, set by the statistics of the compressible flow, that leads to species extinction in fully developed turbulence.
- [57] arXiv:2606.28264 [pdf, html, other]
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Title: A Two-Step Ensemble Score Filter for Data Assimilation in Partially Observed SystemsComments: 23pages, 11 figuresSubjects: Atmospheric and Oceanic Physics (physics.ao-ph)
Data assimilation blends model forecasts with observations to estimate the evolving state of complex dynamical systems, but sparse observing networks remain challenging because unobserved state variables are not directly constrained by observations. In this work, we introduce the Ensemble Score Filter with Linear Regression (EnSF-LR), a two-step filtering method for partially observed nonlinear systems. At each analysis time, EnSF-LR first applies the Ensemble Score Filter (EnSF) to update the observed state components using a nonlinear score-based analysis update. It then computes the resulting observed-state analysis increments and maps these corrections to the unobserved components through the ensemble-based prior covariance matrix. The latter amounts to the same linear regression mechanism used by Ensemble Kalman Filters (EnKFs). We evaluate EnSF-LR using the Lorenz-63 and 40-dimensional Lorenz-96 systems with sparse linear and nonlinear observations. The method is compared with the original EnSF and with the classical stochastic EnKF. In the linear-observation experiments, EnSF-LR produces accuracy comparable to the EnKF baseline while substantially reducing error relative to the original EnSF. In the nonlinear-observation experiments, EnSF-LR achieves lower full-state root-mean-square error than both the original EnSF and the EnKF reference. These results suggest that hybridizing score-based and EnKF analysis schemes provides an effective strategy for assimilating sparse and nonlinear observations.
- [58] arXiv:2606.28318 [pdf, html, other]
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Title: Drift Behavior in a Bounded-Confidence Opinion Model with Media InfluenceSubjects: Physics and Society (physics.soc-ph); Social and Information Networks (cs.SI)
People's opinions can change both from their interactions with each other and from their interactions with media sources. Bounded-confidence models (BCMs) of opinion dynamics provide one framework to study such dynamics. In a BCM, the nodes of a network are agents with continuous-valued opinions, and these agents interact with each other via the edges of the network. In this paper, we extend the original Deffuant--Weisbuch (DW) BCM by incorporating influence from two media sources -- one with a positive value and one with a negative value -- to capture the effects of a polarized media landscape. We show both numerically and analytically that our extended DW model exhibits drifting behavior in which a large cluster of opinions shifts toward one of the media agents. We analyze how the drift trajectory and speed depend on the model parameters, and we identify conditions in which drift is promoted or suppressed. Our results provide insight into how competing media sources can influence collective opinion formation in social systems.
New submissions (showing 58 of 58 entries)
- [59] arXiv:2606.27415 (cross-list from cond-mat.supr-con) [pdf, other]
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Title: Elimination of Flux Trapping in Superconducting Circuits in Ambient Magnetic FieldsRohan T. Kapur, Alex Wynn, Sergey K. Tolpygo, Neel Parmar, Anil Mankame, Adam A. Libson, Rabindra Das, Michele Kelley, Pauli Kehayias, Nathaniel J. O'Connor, Collin N. Muniz, Justin L. Mallek, Jennifer M. SchlossSubjects: Superconductivity (cond-mat.supr-con); Mesoscale and Nanoscale Physics (cond-mat.mes-hall); Applied Physics (physics.app-ph); Quantum Physics (quant-ph)
Superconductor digital electronics and quantum computing with superconducting qubits are promising next-generation computing technologies. When cooled down or operated in the presence of a nonzero background magnetic field $B_r$, superconducting thin films comprising the circuits can trap magnetic vortices that can degrade circuit or qubit performance. In this work, we report a practical solution for eliminating flux trapped during cooldown in ambient magnetic fields, $B_r\leq 60$ $\upmu$T, based on controlled local thermal gradients and moats, etched holes in the superconducting films of the circuit. Thermal gradients created by integrated on-chip resistive heaters move vortices towards the moats, where they become trapped away from circuitry regions and pinning sites. Using magnetic imaging and electrical circuit readout, we demonstrate that this approach is capable of removing magnetic flux trapped during field cooling and magnetic flux nucleated by circuit operation. If used in an environment with basic magnetic shielding, this solution is capable of suppressing all magnetic flux in a large-scale circuit, overcoming one of the long-standing challenges preventing high-performance scalable computing using superconductors.
- [60] arXiv:2606.27478 (cross-list from cond-mat.mes-hall) [pdf, html, other]
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Title: Collection, characterization, and precision measurement of levitated charged nanoparticlesComments: 12 pages, 12 figures. Movie version of Figure 7 is available in ancillary filesSubjects: Mesoscale and Nanoscale Physics (cond-mat.mes-hall); Instrumentation and Detectors (physics.ins-det)
We describe apparatus and experimental procedures for high stability precision measurements of levitated nanoscale particles confined in an ion trap in high vacuum. We discuss methods for particle generation and collection using electrospray emission, for rapid characterization by direct imaging of thermal motion, and for transfer of the particle from the trap where it is collected to a separate analysis trap in order to achieve better vacuum and lower noise. In the analysis trap at high vacuum (pressure $p\simeq10^{-8}$ Torr), we employ thermostatic control of the trapped particle oscillation amplitudes, allowing long-term, precision measurements of oscillation frequencies, from which the charge to mass ratio ($Q/M$) can be deduced. Under these conditions, we achieve $Q/M$ measurement precision approaching $10^{-5}$. This sensitivity will enable, for example, investigations of the surface chemistry of $\mu$m-scale levitated materials in ultra-high vacuum environments.
- [61] arXiv:2606.27515 (cross-list from cs.LG) [pdf, html, other]
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Title: Boundary condition fidelity for bottom-hole pressure and CO2 plume prediction in geological carbon storageSubjects: Machine Learning (cs.LG); Geophysics (physics.geo-ph)
Accurate prediction of bottom-hole pressure (BHP) and CO2 plume migration is essential for safe geological carbon storage, yet practical simulations often rely on truncated domains where artificial boundaries distort pressure diffusion and CO2 saturation footprints. In this study, we evaluate how boundary-condition fidelity affects BHP and CO2 plume prediction by comparing ten reduced-domain boundary treatments against full-domain reference simulations in homogeneous and heterogeneous reservoirs. We test uniform pore-volume multipliers, transmissibility modifiers, corner-adjusted pore-volume corrections, layered corrections, and gradual modifiers using BHP RMSE, NRMSE, peak pressure deviation, and plume Intersection over Union (IoU) as performance metrics. Our results show that conserving corner pore volume is the most important requirement for truncated-domain modeling. We find that uniform treatments which neglect corner storage generate large pressure errors, with BHP RMSE of 362 to 382 psi in the homogeneous model and 250 to 304 psi in the heterogeneous model, and yield plume IoU values near 0.80 to 0.84, indicating roughly 16 to 20% of the combined plume area is misrepresented. Corner-adjusted scenarios substantially reduce pressure errors and raise plume IoU above 0.94, but we observe that transmissibility correction is not universally beneficial. In homogeneous reservoirs, uniform transmissibility adjustment improves pressure fidelity; in heterogeneous reservoirs, it can over-restrict flow across variable-permeability boundary faces, increasing BHP error and contracting the predicted plume. We find the gradual modifier with transmissibility correction provides the most consistent performance, achieving BHP NRMSE below 3.7% and plume IoU above 0.97 in both reservoir types.
- [62] arXiv:2606.27585 (cross-list from astro-ph.IM) [pdf, html, other]
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Title: Experimentally-determined performance limits for joint imaging and wavefront sensing with a photonic lanternAditya R. Sengupta, Vincent Chambouleyron, Rebecca Jensen-Clem, Emiel Por, Benjamin L. Gerard, Jordan Diaz, Zoe Weber-Porter, Yoo Jung Kim, Steph Sallum, Matthew DeMartino, Daren Dillon, Kevin Bundy, Anna K. Gagnebin, Philip Hinz, Caleb Dobias, Tara Crowe, Stephen S. Eikenberry, Rodrigo Amezcua-Correa, Stephanos YerolatsitisComments: submitted to SPIE Astronomical Telescopes and Instrumentation 2026, paper number 14150-167Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Optics (physics.optics)
The photonic lantern (PL) is a focal-plane wavefront sensor (WFS) that can be used for second-stage control of extreme adaptive optics (AO) systems. While the number of sensed modes and the dynamic range with respect to each mode have been relatively well characterized, little attention has been paid to the PL's sensitivity, i.e. how measurement noise impacts the accuracy of PL wavefront reconstruction. We compute the PL's sensitivity to photon noise as a function of spatial frequency, and compare it to existing WFSs, using simulations as well as experiments on the muirSEAL testbed. We further assess these metrics in the case where only a subset of PL ports are available for wavefront sensing. In this configuration, the remaining ports are used to spatially and spectrally reconstruct the observed scene using algorithms such as SPADE. Using more ports for wavefront sensing enables greater aberration sensitivity but leaves less spatial information for image reconstruction. This allows us to trade off between fewer samples with smaller aberrations and more samples with larger aberrations. This work sets the stage for AO system design incorporating the PL as a joint WFS and imager.
- [63] arXiv:2606.27590 (cross-list from astro-ph.IM) [pdf, html, other]
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Title: Laboratory characterization of a multi-photonic lantern optical waveguide using off-axis holographyAditya R. Sengupta, Benjamin L. Gerard, Dominic Sanchez, Matthew DeMartino, Rebecca Jensen-Clem, Kevin Bundy, Michael J. Messerly, Paul Pax, Daren Dillon, Eric StrangComments: submitted to SPIE Astronomical Telescopes and Instrumentation 2026, paper number 14150-135Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Optics (physics.optics)
Photonic lanterns (PLs) are waveguides that convert multi-mode input light to single-mode outputs. Wavefront sensing (WFS) and spectroscopy using a PL have been demonstrated, but PL simulations and experiments show significant mismatches. For the WaveDriver project, a proposed Habitable Worlds Observatory pathfinder that uses a PL for WFS as well as for integral field spectroscopy, we manufactured an optical waveguide consisting of an array of seven 19-port PLs in one device. We present laboratory characterization of the individual PLs, consisting of measurements of the principal modes at each PL input using digital off-axis holography. We compare our mode measurements to simulations to assess the variation in the PL manufacturing process. We discuss expected WFS performance in the WaveDriver configuration.
- [64] arXiv:2606.27643 (cross-list from gr-qc) [pdf, html, other]
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Title: First Demonstration of Optical Feedback Control to Parametric Instability at Advanced LIGOJuntao Pan, Carl Blair, Vladimir Bossilkov, Jian Liu, Alex Adam, Chunnong Zhao, Li Ju, Anamaria EfflerComments: 4 pages, 4 figuresSubjects: General Relativity and Quantum Cosmology (gr-qc); Instrumentation and Methods for Astrophysics (astro-ph.IM); Instrumentation and Detectors (physics.ins-det); Optics (physics.optics)
Increasing the circulating power in gravitational-wave detectors to the megawatt level is essential for future sensitivity improvement, but this is critically limited by optomechanical parametric instabilities. Current mitigation strategies are projected to be inadequate against instabilities when circulating power reaches a megawatt. Optical feedback offers a novel independent paradigm to mitigate parametric instability. In this Letter, we report the first demonstration of optical feedback control in a full-scale gravitational wave detector. We successfully suppressed an unstable mode at 10.428 kHz, reducing the parametric gain from R = 2 to R < 0.02. This work validates optical feedback control as an effective mitigation scheme for kilometre-scale interferometric gravitational-wave detectors, providing an effective strategy to allow detectors to reach the megawatt level.
- [65] arXiv:2606.27646 (cross-list from cs.CV) [pdf, html, other]
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Title: VLM-Aware Meta-Optic Front-End Design for Frozen Vision-Language ModelsComments: 18 pages, 6 figures, 3 tablesSubjects: Computer Vision and Pattern Recognition (cs.CV); Optics (physics.optics)
Conventional machine-vision pipelines typically rely on high-quality optics that produce clean, human-interpretable images, and optical design has therefore been driven by image-level criteria such as resolution, aberration correction, and pixel fidelity. However, such optics are often impractical for size-, cost-, or form-factor-constrained applications, where compact meta-optics offer an attractive alternative but operate under strict physical efficiency limits. We propose CODA, a co-design framework that optimizes a continuous-density meta-optic front-end for frozen-model recognition using differentiable image formation and adjoint-gradient updates of Maxwell-based simulations. CODA directly optimizes the cross-entropy loss of a fixed zero-shot CLIP classifier without learned reconstruction, image signal processing, or image-fidelity auxiliary objectives. In a two-dimensional simulated imaging benchmark on ImageNet-100, CODA improves CLIP ViT-L/14 zero-shot accuracy from 53.75 $\pm$ 3.57$\%$ with a focal-concentration baseline to 65.41 $\pm$ 3.99$\%$. The optimized optics further transfer without re-optimization across CLIP, SigLIP, and DINOv2 on ImageNet-100, CIFAR-100, and Food-101. These results demonstrate that, under constrained meta-optic imaging, downstream recognition can be improved by aligning optical design with frozen vision-model objectives rather than conventional image-formation criteria.
- [66] arXiv:2606.27726 (cross-list from math.NA) [pdf, other]
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Title: Analysis, thermodynamics, and a numeric solver for a pressure-temperature equilibrium closure of the four-equation modelSubjects: Numerical Analysis (math.NA); Computational Physics (physics.comp-ph)
We analyze an often used closure model for multi-material hydrodynamics where pressure temperature equilibrium (PTE) is assumed for every state; emphasis is placed on tabular equations of state. This multi-material model is often referred to as the four-equation model. The identification of the admissible set is presented and is proven to be convex, setting the foundation for development of invariant-domain methods for this model. A novel, robust, and efficient method is presented for solving the highly nonlinear system for the equilibrated pressure and temperature with an arbitrary number of materials. Additionally, we provide a detailed analysis of the thermodynamics of the mixture model for general equations of state and prove existence and uniqueness of the pressure-temperature equilibrium solution under some thermodynamic assumptions.
- [67] arXiv:2606.27787 (cross-list from quant-ph) [pdf, other]
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Title: Industry-ready spin-photon interfaces for hybrid photonic quantum computingHêlio Huet, Hubert Lam, Thibaut Pollet, Petr Steindl, Alice Bernard, Albert Adiyatullin, Petr Stepanov, William Hease, Victor Guilloux, Nico Margaria, Joris Verstraten, Raksha Singla, Samuel T. Mister, Anton Pishchagin, Lara Couronné, Samuel Huber, David Sebastian, Duc Duy Tran, Thi Hao Nhi Nguyen, Thi Phuong Do, Joseph Sulpizio, Yann Portella, Kiarn T. Laverick, Thinhinane Bennour, Tomas Alexandre De Sousa, Davide Stefani, Mathias Pont, Maxime Descampeaux, Bianca Scaparra, Martin A. Jacobsen, Klaus D. Jöns, Rinaldo Trotta, Aristide Lemaître, Martina Morassi, Olivier Krebs, Loïc Lanco, Niels Gregersen, Alexia Auffèves, Maria Maffei, Shane Mansfield, Jean Senellart, Thomas Volz, Viviana Villafañe, Stephen C. Wein, Dario A. Fioretto, Sebastien Boissier, Thi Huong Au, Pascale SenellartComments: 11 pages, 4 figuresSubjects: Quantum Physics (quant-ph); Mesoscale and Nanoscale Physics (cond-mat.mes-hall); Applied Physics (physics.app-ph); Optics (physics.optics)
Hybrid photonic quantum computers, combining stationary matter qubits and flying photonic qubits, offer an intrinsically networked and resource-efficient route to large-scale, error-corrected quantum computation. Their core components are cavity-coupled matter qubits that act as light--matter interfaces, enabling: high-efficiency on-demand single-photon generation, stable near-unity photon indistinguishability and spin--multi-photon entanglement. Semiconductor quantum dots in microcavities are a leading platform for realizing such devices. Yet reaching the performance, reproducibility and spin-coherence thresholds for large-scale error correction remains a major challenge requiring industrial fabrication and control. Here we report thousands of monolithic semiconductor quantum-dot devices fabricated using a III--V pilot production-line process compatible with large-scale deployment. Systematic control of source parameters yields state-of-the-art efficiency and supports a path to optical losses below fault-tolerance thresholds. Using field-quadrature state reconstruction as a stringent joint test of efficiency and indistinguishability, we observe near-unity photon quantum purity stable over tens of minutes and a record single-photon Wigner-function negativity. We further demonstrate seven-partite spin--multi-photon entanglement and spin coherence extendable to microsecond timescales in the low-magnetic-field regime. Finally, photons from distant sources are as indistinguishable as photons emitted successively by a single source. These results establish foundry-compatible III--V quantum dots as a scalable platform for hybrid photonic quantum computing.
- [68] arXiv:2606.27810 (cross-list from cond-mat.mes-hall) [pdf, html, other]
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Title: Exceptional Points as Manifestations of Topological-Charge Breakdown in a Non-Hermitian SkyrmionComments: 10 pages, 2 figures. Companion to "Exceptional Points as Manifestations of Analyticity Breakdown in the 't Hooft Model" (submitted to SciPost Physics). Data and code: this https URLSubjects: Mesoscale and Nanoscale Physics (cond-mat.mes-hall); Other Condensed Matter (cond-mat.other); Optics (physics.optics)
The integer topological charge of a magnetic skyrmion is the standard emblem of topological protection. We ask what happens to that protection when the magnet is made non-Hermitian, with balanced gain and loss or a PT-symmetric anisotropy. A non-Hermitian skyrmion turns out to carry two charges that coincide in the Hermitian limit but part ways under deformation. The charge built from the right state alone is homotopy-protected: the PT flow reduces exactly to a Gilbert-type relaxation on the target sphere, so it cannot change under smooth evolution. The charge built from the biorthogonal left-right pair is complex, loses quantization as soon as the gain/loss is turned on, and breaks down at the exceptional point of the local generator -- a ring on the skyrmion's equator, where the biorthogonal Bloch field itself diverges. Topological protection of a skyrmion is therefore not a single statement once the dynamics is non-Hermitian: it splits at an exceptional point. This is the real-space topological counterpart of the analyticity breakdown a causal response function suffers at an exceptional point, both being manifestations of the same non-Hermitian degeneracy.
- [69] arXiv:2606.27817 (cross-list from quant-ph) [pdf, html, other]
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Title: Detector-Conditioned Source-Space Nulls and Null-Mask Loss in a Programmable Two-Slit InterferometerSubjects: Quantum Physics (quant-ph); Optics (physics.optics)
Afshar's double-slit experiment probes wave--particle complementarity by placing a wire grid at the dark fringes of a downstream interference pattern while retaining an imaging basis that appears to preserve which-path information. Here we propose and analyze a time-reversed Young--Afshar configuration in which the corresponding null test is transferred from the downstream field plane to the source-label plane of a time-reversed Young interferometer. In this reciprocal geometry, a point-addressable source illuminates a double slit, while the detector remains fixed. The observed fringe is therefore not a single-shot spatial intensity pattern, but a detector-conditioned response reconstructed by scanning the source coordinate. Consequently, a null in this pattern is not a node of a freely propagating field; it is a source label for which the coherent two-slit transfer amplitude to the selected detector vanishes. A mask placed at such source-plane labels is invisible to that detector when both slits are open, yet becomes visible when either slit is opened alone. We develop the scalar Fresnel model, derive the source-space null condition, introduce a detector-conditioned null-mask loss, and examine how this loss evolves under a tunable which-path marker. The source-space visibility and path distinguishability satisfy the standard duality relation, so no violation of complementarity is implied. The essential new feature is instead a reciprocal, detector-conditioned form of complementarity: Afshar's field-space transparency is replaced by response-function transparency in a reconstructed source basis.
- [70] arXiv:2606.27823 (cross-list from cond-mat.quant-gas) [pdf, html, other]
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Title: Universality in strongly interacting bosonic clustersComments: 7+8 pages, 3+8 figuresSubjects: Quantum Gases (cond-mat.quant-gas); Nuclear Theory (nucl-th); Atomic and Molecular Clusters (physics.atm-clus)
We develop an effective field theory (EFT) for strongly interacting bosonic clusters, using $^4$He as a paradigmatic example of universality in systems with large scattering length. At leading order (LO), two- and three-body zero-range interactions are entirely determined by the dimer and trimer ground-state energies. We show that ground-state energies for up to $N=15$ particles converge to cutoff-independent limits with extrapolation coefficients of natural size. At next-to-leading order (NLO), corrections stemming from the two-body interaction range and a four-body force, calibrated to the tetramer ground-state energy, reduce cutoff sensitivity. Close agreement with results from a realistic potential is found at LO and improved at NLO, demonstrating systematic convergence with few parameters at each order. The resulting EFT is directly applicable to larger clusters and bulk helium.
- [71] arXiv:2606.27887 (cross-list from cond-mat.mtrl-sci) [pdf, other]
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Title: Unlocking Cryogenic Energy Storage by Constructing Dipole Glass with Unit-cell-level Polar DisorderYangyang Si, Denan Li, Yijie Li, Changsheng Chen, Jingxuan Li, Chao Zhou, Hao Xiong, Tianfu Zhang, Wenjin Liao, Zhongqi Ren, Huaicheng Yuan, Dong Li, Jing-Kai Qin, Cheng-Yan Xu, Ye Zhu, Yunlong Tang, Sujit Das, Jieun Kim, Junling Wang, Hao Pan, Fei Li, Zhen Chen, Shi Liu, Zuhuang ChenComments: 23 pages, 4 figuresSubjects: Materials Science (cond-mat.mtrl-sci); Applied Physics (physics.app-ph)
Cryogenic energy storage is vital for frontier technologies including deep-space exploration and quantum computing, yet conventional electrochemical energy systems fail below ~230 K due to frozen ion migration. While relaxor-based dielectric capacitors provide high efficiency at room temperature, the intrinsic freezing/growth of polar nanodomains at extended cryogenic regime limits their applications with deteriorated hysteresis losses. Here, we realize superior cryogenic energy-storage performance by designing unit-cell-level disordered dipole-glass state in Pb0.6Sr0.4ZrO3 thin films with composition near antiferroelectric-paraelectric phase boundary. The antiferroelectric-derived dipole-glass introduces enhanced unit-cell-level complexity of dipole interaction that suppresses long-range ferroelectric order. This enables ultralow-hysteresis operation (efficiency > 88%) down to 4 K, delivering record-high energy density (211 J/cm^3) at 9 MV/cm, stability over 10^8 charge/discharge cycles and microsecond-scale charge/discharge capability. This work establishes a dipole-glass paradigm for cryogenic dielectric capacitors, opening a new avenue to highly-efficient energy-storage systems with broad applications in frontier nanoelectronics.
- [72] arXiv:2606.27928 (cross-list from hep-th) [pdf, other]
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Title: $\texttt{SMaSH}$ : Simplify Massive Spinor HelicityComments: 136 pages, 1 figure. Mathematica files are included in the ancillary file. Github link for the package is this https URLSubjects: High Energy Physics - Theory (hep-th); High Energy Physics - Phenomenology (hep-ph); Computational Physics (physics.comp-ph)
We present $\texttt{SMaSH}$, a $\texttt{Mathematica}$ package to do spinor helicity computations in four spacetime dimensions $\href{this https URL}{\text{(github)}}$. It can handle massive spinor helicity computations with explicit little group indices which is a novel feature. It can also handle massless as well as off-shell spinor helicity variables. It is designed to compute perturbative computations; it comes with predefined three point amplitudes and propagators for any masses and spins (arXiv:1709.04891). It can implement the high energy limit over an expression, check the discrete $\tt{C,P,T}$ transformations, compute contact terms and impose gauge invariance for any scattering process. We have shown the usage of such functions for computing gauge invariant Weinberg minimal amplitudes (arXiv:2506:12431, arXiv:2504:06343).
The package can also generate both real and complex numerical kinematics for any $n$-point scattering for arbitrary masses and energy scales by implementing the $\tt{RAMBO}$ algorithm. It is also rich with basic spinor helicity manipulations like Schouten simplification, Clifford algebra manipulation, conversion between spinor helicity and Lorentz vectors, derivative w.r.t. spinors and their scalars, helicity scaling etc. - [73] arXiv:2606.27942 (cross-list from q-bio.BM) [pdf, other]
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Title: Towards coevolution-aware ancestral sequence reconstructionAlya Zeinaty, Leonardo di Bari, Saverio Rossi, Pierre Barrat-Charlaix, Francesco Zamponi, Martin WeigtComments: 20 pages, 5 figuresSubjects: Biomolecules (q-bio.BM); Biological Physics (physics.bio-ph); Populations and Evolution (q-bio.PE)
Ancestral sequence reconstruction (ASR) is a powerful approach for studying molecular evolution and the emergence of protein function. Yet most ASR methods assume that sites evolve independently, neglecting the epistatic constraints that shape protein structure, stability, and function. This simplification affects both ancestral inference and its evaluation: maximum-a-posteriori reconstructions may over-concentrate probability into a single over-idealized sequence, whereas independent posterior sampling can generate implausible or poorly functional ancestors. Here, we introduce a coevolution-aware ASR framework that combines standard phylogenetic inference with Direct Coupling Analysis (DCA), thereby preserving site-wise ancestral uncertainty while enforcing residue-residue constraints learned from extant protein families. To benchmark the method, we develop a controlled forward-evolution framework based on a DCA evolutionary sampler, allowing reconstructed ancestors to be compared with known ground-truth sequences generated under realistic epistatic constraints. Applied to beta-lactamases and DNA-binding domains, the approach improves reconstruction when ancestral states are epistatically constrained, and yields ensembles of candidate ancestors that are both phylogenetically consistent and statistically compatible with natural protein families. This framework bridges the gap between single-sequence MAP reconstruction and unconstrained posterior sampling, providing a practical route toward ancestral reconstructions that better reflect the coupled nature of protein evolution.
- [74] arXiv:2606.27951 (cross-list from cs.CY) [pdf, html, other]
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Title: AI Persuasive Framing in Collective DilemmasComments: The first two authors contributed equally to this research. The article contains 20 pages, 10 figures, and 2 tablesSubjects: Computers and Society (cs.CY); Computation and Language (cs.CL); Human-Computer Interaction (cs.HC); Physics and Society (physics.soc-ph)
AI agents are promising tools that can act as flexible behavioral nudges to enhance human cooperation in addressing large-scale societal problems. However, evidence on whether AI agents can effectively boost cooperation remains mixed. We recruited 1,283 participants to play iterated Collective Risk Games in small groups, testing whether AI assistants could nudge participants toward cooperation. By using persuasive framing personalized to each player's Social Value Orientation profile, the AI interventions significantly increased contributions and group success rates. These cooperative effects were short-lived, however, fading after the first few rounds. Strikingly, when the AI treatments were reconfigured to promote selfish behavior through exculpatory framing, the negative effects on contributions and group success were larger and substantially more persistent, particularly for personalized interventions. This asymmetry between prosocial and antisocial persuasion highlights the dual-use risks of AI systems designed to influence group behavior in collective action settings.
- [75] arXiv:2606.27972 (cross-list from cond-mat.stat-mech) [pdf, html, other]
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Title: A Finite Element Method for Fluctuating Navier--Stokes EquationsSubjects: Statistical Mechanics (cond-mat.stat-mech); Numerical Analysis (math.NA); Fluid Dynamics (physics.flu-dyn)
We introduce a finite-element framework for simulating thermal fluctuations in compressible fluids governed by the fluctuating Navier-Stokes equations. The method is designed to preserve the fundamental fluctuation-dissipation balance at the discrete level. This is achieved by defining the stochastic forcing term in the weak formulation, ensuring its covariance is proportional to the discrete viscous dissipation operator. A nodal quadrature rule is employed to eliminate unphysical mesh-scale correlations. The time integration is performed using the Crank-Nicolson scheme to maintain numerical stability and accuracy. The proposed approach is numerically validated in one, two, and three spatial dimensions, demonstrating its capability to correctly capture equilibrium fluctuation statistics across various discretisation parameters.
- [76] arXiv:2606.27983 (cross-list from q-bio.PE) [pdf, html, other]
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Title: Reconstructability of evolutionary intermediates in generative epistatic landscapesComments: 15 pages, 4 figures + supplementary appendixSubjects: Populations and Evolution (q-bio.PE); Biological Physics (physics.bio-ph); Biomolecules (q-bio.BM)
Evolutionary intermediates connect observed proteins, but the sequence of steps that produced them is rarely recoverable from extant data alone. Here we ask what can, and cannot, be inferred about such intermediates from the endpoints. Using generative sequence landscapes as controlled models of protein-family evolution, we benchmark data-driven reconstruction against ground-truth simulated trajectories. We find that the best point prediction is not necessarily the most faithful evolutionary reconstruction: maximum-likelihood intermediates can be residue-wise accurate yet statistically atypical, whereas conditional sampling better captures the ensemble of plausible histories. Predictability is limited by the topology of the landscape. Constrained, low-mutability regions preserve information about the path, while permissive high-mutability regions open many alternative routes and erase path-specific memory. We also show that sequence divergence alone is an insufficient measure of elapsed evolutionary time; incorporating endpoint mutability provides a more reliable way to place intermediates in the landscape. These results recast intermediate reconstruction as a calibrated probabilistic problem. Rather than seeking a single "true" sequence, data-driven models should identify when endpoints contain evolutionary information, and return realistic ensembles.
- [77] arXiv:2606.27985 (cross-list from cond-mat.stat-mech) [pdf, other]
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Title: Nonextensive Statistical Signatures of the Bilaterian Transition in Proteome Length DistributionsComments: Submitted to Eur. Phys. J. ESubjects: Statistical Mechanics (cond-mat.stat-mech); Biological Physics (physics.bio-ph)
Protein length distributions across the tree of life carry a quantitative signature of organismal complexity. Nonextensive statistical mechanics, through the Tsallis generalized entropy formalism, provides a natural framework for describing complex systems characterized by long-range correlations, scale invariance, and hierarchical organization -- features that classical Boltzmann-Gibbs statistics cannot accommodate. In this work, the complementary cumulative distribution function (CCDF) of protein lengths is analyzed within this framework for the reference proteomes of 22 fully sequenced organisms spanning the domains Archaea, Bacteria, and Eukarya, with deliberate sampling across the animal transition zone from sponges and cnidarians to higher bilaterians. Maximum likelihood (MLE) fitting of truncated discrete q-exponential distributions, with bootstrap 95% confidence intervals (CIs) reveals that the entropic index q resolves into three statistically distinct regimes: superextensive (q < 1) for prokaryotes, unicellular and non-animal multicellular eukaryotes, and basal animals; a boundary regime (CI on spanning unity) for the two cnidarians studied and the basal bilaterian C. teleta; and subextensive (q > 1) for all higher bilaterians, with q increasing monotonically across the four deuterostomes sampled from S. purpuratus (1.033) to H. sapiens (1.147). The q-exponential outperforms the ordinary exponential distribution across all 22 proteomes and becomes progressively more competitive against alternative two-parameter distributions as proteome complexity increases. These results identify the Tsallis entropic index as a continuous, physically interpretable indicator of proteome organizational complexity and extend the applicability of nonextensive statistical mechanics to proteomic systems.
- [78] arXiv:2606.28051 (cross-list from astro-ph.IM) [pdf, html, other]
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Title: The performance of the TA$\times$4 surface detector array: 4.3 years of the first-half expansionTelescope Array Collaboration: R.U. Abbasi (1), T. Abu-Zayyad (1,2), M. Allen (2), J.W. Belz (2), D.R. Bergman (2), F. Bradfield (3), I. Buckland (2), W. Campbell (2), B.G. Cheon (4), K. Endo (3), A. Fedynitch (5,6), T. Fujii (3,7), K. Fujisue (5,6), K. Fujita (5), M. Fukushima (5), G. Furlich (2), A. Gálvez Ureña (8), Z. Gerber (2), N. Globus (9), T. Hanaoka (10), W. Hanlon (2), N. Hayashida (11), H. He (12), K. Hibino (11), R. Higuchi (5,12), D. Ikeda (11), D. Ivanov (2), S. Jeong (13), C.C.H. Jui (2), K. Kadota (14), F. Kakimoto (11), O. Kalashev (15), K. Kasahara (16), Y. Kawachi (3), K. Kawata (5), I. Kharuk (15), E. Kido (5,12), H.B. Kim (4), J.H. Kim (2), J.H. Kim (2), S.W. Kim (13), R. Kobo (3), I. Komae (3), K. Komatsu (17), K. Komori (10), A. Korochkin (18), C. Koyama (5), M. Kudenko (15), M. Kuroiwa (17), Y. Kusumori (10), M. Kuznetsov (15), Y.J. Kwon (19), K.H. Lee (4), M.J. Lee (13), B. Lubsandorzhiev (15), J.P. Lundquist (2,20), H. Matsushita (3), A. Matsuzawa (17), J.A. Matthews (2), J.N. Matthews (2), K. Mizuno (17), M. Mori (10), S. Nagataki (12), K. Nakagawa (3), M. Nakahara (3), H. Nakamura (10), T. Nakamura (21), T. Nakayama (17), Y. Nakayama (10), K. Nakazawa (10), T. Nonaka (5), S. Ogio (5), H. Ohoka (5), N. Okazaki (5), M. Onishi (5), A. Oshima (22), H. Oshima (23), S. Ozawa (24), I.H. Park (13), K.Y. Park (4), M. Potts (2), M. Przybylak (25), M.S. Pshirkov (15,26), J. Remington (2), C. Rott (2), G.I. Rubtsov (15), D. Ryu (27), H. Sagawa (5), N. Sakaki (5), R. Sakamoto (10), T. Sako (5), N. Sakurai (5), S. Sakurai (3), D. Sato (17), K. Sekino (5), T. Shibata (5), J. Shikita (3), H. Shimodaira (5), H.S. ShinComments: 24 pages, 9 figures, submitted to Nuclear Inst. and Methods in Physics Research, ASubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Instrumentation and Detectors (physics.ins-det)
The Telescope Array (TA) experiment aims to reveal the origin of ultra-high-energy cosmic rays (UHECRs) by observing air showers using surface detectors (SDs), which spread over an area of approximately 700 km$^2$, and fluorescence detectors (FDs) viewing the skies above the SD array. The TA experiment has been observing UHECRs since 2008, and has reported an indication of clustering in the arrival directions of cosmic-ray events with energy greater than 57 EeV. To improve the exposure for anisotropy studies of UHECRs, the TA$\times$4 upgrade was designed to expand the observational area by approximately 2,000 km$^2$ with 500 additional SDs. Half of the planned upgrade, consisting of 257 SDs, was completed, and the newly installed array began operation in 2019. In addition to the expanded SD array, two FD stations were constructed for the TA$\times$4 experiment. In this paper, we present a study of the performance of the expanded SD array, including the energy resolution, angular resolution, and effective aperture, over the first 4.3 years of data acquisition. While the effective aperture varied initially due to changing detector states, it has stabilized since June 2023 with more than 90\% operational SDs. Furthermore, a new inter-tower trigger system was implemented to connect six new communication towers to form two geographically separated arrays, increasing the effective aperture. The time variation of this effective aperture, the resulting total exposure of approximately 3,500 km$^2$~sr~yr, and a comparison with the original TA SD array are presented to demonstrate the performance of the expanded array.
- [79] arXiv:2606.28056 (cross-list from cond-mat.mes-hall) [pdf, other]
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Title: Determining Electron Beam Lateral Coherence in a Scanning Electron Microscope Using Electron DiffractionEvelijn Akerboom, Fatemeh Kiani, Giulia Tagliabue, Wiebke Albrecht, Joanne Etheridge, F. Javier García de Abajo, Albert PolmanComments: 14 pages, 7 figures, with appendixSubjects: Mesoscale and Nanoscale Physics (cond-mat.mes-hall); Atomic and Molecular Clusters (physics.atm-clus)
We develop and characterize scanning transmission electron microscopy (STEM) capabilities within a scanning electron microscope (SEM) to investigate the effective lateral coherence of the electron beam (e-beam) in the specimen plane. Using single-crystalline Au flakes and a sample composed of a monolayer of graphene, we obtain high-quality selected-area electron diffraction (SAED) maps and convergent-beam electron diffraction (CBED) patterns, validating the systems ability to probe crystallographic information at an acceleration voltage of 30 keV. Building on these capabilities, we implement a method, which is adapted from techniques traditionally used in transmission electron microscopy, to measure the degree of lateral coherence of the e-beam in the specimen plane of the SEM. By analyzing interference between electrons with two different wave vectors separated by 0.031 per angstrom, we extract a lower limit for the degree of lateral coherence over 5% of the e-beam diameter of approximately 60%. These coherence values are sufficient to enable quantum-coherent electron-light-matter interaction experiments in the SEM.
- [80] arXiv:2606.28078 (cross-list from quant-ph) [pdf, html, other]
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Title: Single Electrons in a Dual-Plane Printed-Circuit-Board Penning TrapComments: 10 pages, 8 figures, submitted to Phys. Rev. AppliedSubjects: Quantum Physics (quant-ph); Atomic Physics (physics.atom-ph)
We demonstrate single-electron trapping and detection in a two-dimensionally scalable dual-plane printed-circuit-board Penning trap. We characterize deterministic electron loading, axial damping, axial temperature, and collision-induced magnetron-radius growth at low magnetic fields. These results establish a practical platform for planar Penning traps and identify key next steps toward applications in quantum information science.
- [81] arXiv:2606.28101 (cross-list from astro-ph.IM) [pdf, html, other]
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Title: In-flight calibration of the Wide-field X-ray Telescope on board the Einstein ProbeHuaqing Cheng, Hai-Wu Pan, Yuan Liu, Jingwei Hu, Haonan Yang, Donghua Zhao, Zhixing Ling, Yifan Chen, Xiaojin Sun, Longhui Li, Ge Jin, Wenxin Wang, Xue Yang, He-Yang Liu, Chen Zhang, Shuang-Nan Zhang, Weimin YuanComments: 13 pages, 13 figures, 3 tables. Submitted to Astronomy & AstrophysicsSubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Experiment (hep-ex); Instrumentation and Detectors (physics.ins-det)
By utilizing novel lobster-eye optics, the Wide-field X-ray Telescope (WXT) onboard the Einstein Probe (EP) satellite achieves an unprecedented combination of a large instantaneous field-of-view (FoV) and high sensitivity for monitoring the dynamic X-ray sky. In this paper, we present the in-orbit calibration results of the WXT during its first two and a half years of operations. By conducting observations of standard celestial sources--including the Crab Nebula, Scorpius X-1, and Cassiopeia A--we systematically characterized key instrumental properties. Our analysis demonstrates that the in-orbit performance of the WXT agrees with prelaunch ground calibrations well. The spatial resolution, denoted by the full width at half maximum (FWHM) of the focal spot, typically ranges from $3'$ to $6'$ across $\sim$90% of the FoV, with a median of $\sim 4.3'$. The post-calibration source positioning accuracy achieves $1.3'$ (at the 90% confidence level). The in-orbit effective area is consistent with model predictions and ground measurements, exhibiting an overall systematic uncertainty of $\lesssim 10\%$ (90% C.L.) in the 0.5-4 keV band. While the vast majority of the detectors remain highly stable, a noticeable long-term degradation at the low-energy end ($\sim30\%$-$40\%$, 0.4-0.6 keV) is observed in a few specific modules. Furthermore, spectral evaluations using Cas A confirm the stability of the energy scale and spectral resolution of the focal-plane Complementary Metal-Oxide Semiconductor (CMOS) detectors. All derived calibration products have been incorporated into the WXT calibration database (CALDB). These results comprehensively verify the instrumental capabilities of the WXT, providing a solid foundation for the reliable analysis of scientific observations.
- [82] arXiv:2606.28130 (cross-list from quant-ph) [pdf, html, other]
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Title: A Reproducible Pipeline for Symmetry-Respecting Excited States on Near-Term Quantum Computers: The H2O/STO-3G CaseSubjects: Quantum Physics (quant-ph); Chemical Physics (physics.chem-ph)
Variational excited-state quantum algorithms fail for reasons usually studied in isolation: barren plateaus, symmetry contamination, finite-sampling instability, and hardware cost. Using one small but complete system -- H$_2$O in the STO-3G basis (12 qubits, Jordan--Wigner) -- we assemble these into a single reproducible pipeline, checking every claim against exact diagonalization. The bare qubit Hamiltonian interleaves cation ($N{=}7$) states below the neutral manifold; hardware-efficient and number-conserving ansätze stall at Hartree--Fock, an exact stationary point by Brillouin's theorem, while ADAPT-VQE escapes; variational deflation inherits the contamination and inverts the spectrum, whereas the quantum equation-of-motion (qEOM) subspace method restores the ladder to sub-milli-Hartree accuracy. Particle number is protected \emph{structurally} under shot noise, and a realistic measurement model collapses the thousands of subspace matrix elements to $\sim\!10^5$ commuting groups; a matrix-aware shot allocation then reaches chemical accuracy at $\sim\!3\times10^9$ total shots -- a thousandfold below the naive per-element estimate and reachable in days -- leaving single-circuit gate fidelity, not measurement, as the binding constraint. This work is a teaching and benchmarking reference, not a new method; all code, parameters, and figures are released.
- [83] arXiv:2606.28136 (cross-list from astro-ph.IM) [pdf, html, other]
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Title: Differentiable design of the PIAA-ZWFS: a flexible wavefront sensor that approaches the fundamental limitComments: Submitted to Astronomy & Astrophysics (A&A)Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Computer Vision and Pattern Recognition (cs.CV); Optics (physics.optics)
Extreme adaptive optics (AO) is necessary for high contrast astronomy at scales of the habitable zone of nearby systems. We seek to evaluate wavefront sensors that approach fundamental limits of wavefront sensing, enabling adaptive optics systems to run faster or on fainter targets. We present the phase-induced amplitude apodisation Zernike wavefront sensor (PIAA-ZWFS): an adaptation of the conventional Zernike wavefront sensor (ZWFS) that leverages lossless apodisation of the pupil to concentrate the starlight in the focal plane. We optimise and evaluate the sensor with a differentiable modelling framework, drawing on concepts from Bayesian experimental design to minimise the variance of a maximum likelihood estimator that uses the system in the high Strehl regime. Our architecture shows state-of-the-art performance in simulation for different apertures, bandwidths, photon fluxes and source sizes, closing the gap to the fundamental limit by a factor 10 (2.5) compared to the conventional ZWFS (optimised ZWFS) in a typical photon-limited case. For extended sources, we show that even an ideal point source sensor rapidly becomes sub-optimal, and our system outperforms it for stellar diameters larger than 0.8{\lambda}/D. We verify that these gains do not come at the cost of dynamic range with either linear or non-linear reconstructors. Finally, we present a proof that there must be a trade-off between the information gained about amplitude and phase errors for any wavefront sensor. The PIAA-ZWFS is a viable wavefront sensor operating near the fundamental sensitivity limits.
- [84] arXiv:2606.28178 (cross-list from quant-ph) [pdf, html, other]
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Title: Vacuum Fluctuation-Induced State Switching in Degenerate Optical Parametric OscillatorsYihao Huang, Seou Choi, Rom Simovitch, Jamison Sloan, Charles Roques-Carmes, Michael Horodynski, Marin Soljačić, Yannick SalaminSubjects: Quantum Physics (quant-ph); Optics (physics.optics)
Bistable driven-dissipative systems near bifurcations can exhibit noise-activated switching between steady states. Here, we investigate how quantum vacuum fluctuations induce such switching in a biased optical parametric oscillator (OPO), a nonlinear system with intrinsic bistability. We show how microscopic quantum fluctuations driving macroscopic transitions can be controlled with an external bias field that reshapes the OPO steady-state metapotential. We derive analytical expressions for the average switching time and validate them through simulations of the OPO field distribution and inter-state probability flow under bias injection. We further examine how switching depends on bias strength, pump gain, and optical nonlinearity. Our findings clarify how quantum noise can shape macroscopic dynamics and provide a foundation for noise-assisted photonic machine learning and probabilistic quantum gates.
- [85] arXiv:2606.28180 (cross-list from astro-ph.IM) [pdf, html, other]
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Title: Radiation tolerance of a diamond radiation detector for space useYoshiyuki Ando, Shutaro Ueda, Ryota Heibatake, Kaito Ozawa, Makoto Arimoto, Tatsuya Sawano, Daisuke Yonetoku, Kimiyoshi Ichikawa, Norio Tokuda, Taichi Miyazaki, Shoya Matsuda, Yasuhiro Shoji, Satoshi Hatori, Kyo Kume, Shinko Sando, Satoshi MizushimaComments: 11 pages, 6 figures, NIMA in pressSubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Detectors (physics.ins-det)
We present a study of the radiation tolerance of two types of diamond radiation detectors for space use. We plan to launch a 3U-size CubeSat, KSAT3-X, developed by Kanazawa University in 2027. The KSAT3-X mission is aimed to observe inflows and outflows of charged particles such as electrons and protons, particularly in the 10 - 40 keV energy range, in the Earth's magnetosphere. As the mission instrument, we have developed two diamond radiation detectors. The first is composed of a microwave plasma chemical vapor deposition (MPCVD) diamond fabricated by Element Six, and the second is based on a MPCVD diamond produced in-house at Kanazawa University. We irradiate both diamonds with 100 MeV protons and evaluate their spectroscopic performance as an indicator of radiation tolerance using characteristic X-rays from radioisotope sources. We find no significant degradation in their spectroscopic performance up to at least the 10-year equivalent irradiation under the orbital environments of KSAT3-X. We additionally irradiate the Element Six diamond with 100 MeV protons up to the 100-year equivalent. As a result, no significant degradation in the spectroscopic performance is observed. These results indicate that the two diamond radiation detectors have sufficiently high radiation tolerance. We also discuss possible physical origins of the observed difference in the spectroscopic performance between the two detectors.
- [86] arXiv:2606.28181 (cross-list from cond-mat.soft) [pdf, html, other]
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Title: Universality of Bubble Coalescence in Electrolytic MediaSubjects: Soft Condensed Matter (cond-mat.soft); Fluid Dynamics (physics.flu-dyn)
Bubble coalescence phenomenon in electrolytic media finds applications in technologies from mineral flotation to electrochemical energy conversion. However, the underlying governing physics still remains unresolved, with longstanding disagreement over the extent to which Marangoni stresses affect the coalescence time by modulating the interfacial mobility. Here, we show that the thin film morphology governs drainage more strongly than the interfacial boundary conditions. We demonstrate experimentally that thin film drainage during bubble coalescence proceeds through three distinct regimes. An initial visco-capillary stage that exhibits a power-law thinning, followed by an exponential decrease in film thickness with time induced by rim stabilisation. The final regime is governed by disjoining pressure and is marked by an exponential relaxation of the film to the equilibrium thickness. We show that, irrespective of the electrolyte type and concentration, film evolution exhibits universal behavior by collapsing onto a single curve when rescaled with the characteristic film thickness and time scale, demonstrating that electrolyte effects act only to renormalize timescales rather than alter the underlying dynamics.
- [87] arXiv:2606.28184 (cross-list from math.NA) [pdf, html, other]
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Title: A fast sum-of-Gaussians algorithm for the high-dimensional fractional Fokker-Planck equationComments: 39 pages, 5 figuresSubjects: Numerical Analysis (math.NA); Computational Physics (physics.comp-ph)
We present a fast, high-order algorithm for the free-space fractional Fokker-Planck equation (FFPE) in arbitrary spatial dimension. Its fundamental solution, corresponding to a Dirac-delta initial condition, is obtained from the explicit Fourier representation by applying a sum-of-Gaussians (SOG) approximation to the nonseparable stretched exponential, using its complete monotonicity as the Laplace transform of a one-sided $\alpha$-stable density. Each Gaussian term is an ordinary heat kernel and therefore factorizes across spatial coordinates. On a tensor-product grid, the separated form can be assembled in $O(MdN)$ work and storage, rather than forming all $O(N^d)$ grid values, where $M$ is the number of Gaussian terms and $N$ is the number of points per dimension. We prove an a~priori error estimate for the pure-fractional fundamental solution and give a parameter-selection procedure for prescribed accuracy over specified ranges of space and time. In numerical experiments the method achieves more than ten digits of relative accuracy, with $M$ growing only logarithmically in the inverse tolerance, and maintains this accuracy in dimensions up to $d=10^{5}$. This exceeds the dimensions reached in comparable radial-quadrature tests, where the integrand becomes increasingly oscillatory as the dimension grows. Because the method represents the fundamental solution as a separated sum of heat kernels, any initial datum given as a finite sum of tensor products can be evolved in closed form using only one-dimensional convolutions. This yields a computable class of high-dimensional solutions that is amenable to error analysis, and tensor neural networks provide one possible way to construct such separated representations for more general data.
- [88] arXiv:2606.28233 (cross-list from cond-mat.quant-gas) [pdf, html, other]
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Title: Coexisting Regular and Chaotic Dynamics in the Dysprosium Feshbach SpectrumJulie Veschambre, Alexandre Journeaux, Maxime Lecomte, Alice Belmon, Ethan Uzan, Inès de Verdelhan, Patricia Christina Marques Castilho, Jakub Zakrzewski, Jean Dalibard, Raphael LopesComments: 9 pages, 5 figuresSubjects: Quantum Gases (cond-mat.quant-gas); Chaotic Dynamics (nlin.CD); Atomic Physics (physics.atom-ph)
Strongly dipolar gases, such as dysprosium, erbium and thulium, exhibit dense Feshbach spectra whose level statistics have been associated with quantum chaos arising from couplings among many molecular channels. Here, we combine a precise calibration of the Feshbach spectrum of $^{162}$Dy with spectroscopic measurements of the differential magnetic moments of bound states associated with more than 80 resonances between 0 and 30 G. These magnetic moments provide an eigenstate-sensitive probe of the molecular states underlying the resonance spectrum. We find that the level statistics are not uniform: resonances associated with states near the center of the magnetic-moment distribution display enhanced level repulsion, whereas those near the lower edge remain close to Poisson statistics. Our results reveal hidden structure within the chaotic dysprosium Feshbach spectrum and identify molecular-state composition as a key ingredient in the emergence of quantum chaos in strongly dipolar scattering.
- [89] arXiv:2606.28255 (cross-list from quant-ph) [pdf, other]
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Title: Efficient targeting of arbitrary excited states with quantum inverse power iteration through filtering polynomialsComments: 32 pages, 12 figures, plus appendixSubjects: Quantum Physics (quant-ph); Chemical Physics (physics.chem-ph)
In this work, we introduce a quantum inverse power iteration (QIPI) algorithm based on the quantum singular value transformation (QSVT) to target arbitrary excited states. Given an energy shift $\omega$, QIPI prepares the target excited state by iteratively applying an approximation of the shifted inverse Hamiltonian $(H-\omega I)^{-1}$ to a trial state. Prior quantum inverse power approaches typically relied on Fourier decompositions of the inverse Hamiltonian, with numerical quadrature used to reconstruct the transformation, but such methods are highly sensitive to hyperparameter choices and have been observed to be numerically unstable, effectively restricting their use to ground-state preparation. To enable robust excited-state targeting, we investigate two alternative transformation techniques: a Chebyshev decomposition of the inverse (Cheb-inv) and an eigenstate filtering (EF) approach based on QSVT. We find that EF-based QIPI is substantially more robust than Cheb-inv and other decomposition-based approaches due to the symmetry of the applied filtering polynomial, avoiding divergence with respect to the choice of $\omega$ and efficiently suppressing off-target eigenstates even in closely spaced spectra. Numerical simulations for molecular Hamiltonians of H$_2$, LiH, and BeH$_2$ show improved convergence and enhanced access to higher excited states relative to other quantum power methods. Assuming standard oracle access to the Hamiltonian, we further provide logical resource estimates in fault-tolerant settings in terms of T gate counts, and conclude that QIPI can achieve high target state amplification with modest polynomial degrees, thereby making it a promising candidate for scalable excited-state preparation in fault-tolerant quantum chemistry applications.
- [90] arXiv:2606.28280 (cross-list from hep-th) [pdf, html, other]
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Title: Surface Water Wave Scattering and the HydrotopeComments: 7 pages, 3 figures + Supplemental Material + GitHub repositorySubjects: High Energy Physics - Theory (hep-th); Fluid Dynamics (physics.flu-dyn)
We study the classical tree-level scattering amplitudes of deep-water surface gravity waves using the methods of high-energy physics. For scattering in one horizontal dimension and in the two-negative-wavenumber sector we obtain a closed formula for $n$-wave scattering. Up to a kinematic prefactor, the amplitude is the volume of a classic polytope -- a box sliced by a hyperplane, which we dub the hydrotope, whose purpose in life is simply to organize the sign patterns of the "chambers" characterizing all the different regions of the two-minus kinematic space. The general formula was discovered by Claude Opus 4.6 working under our guidance, beginning with our earlier discovery of a one-term expression valid in the "simplest" kinematic chamber. Our results resolve the puzzle raised by Y.V. Lvov's 1997 computation of the five-wave amplitudes, unifying and extending it to all multiplicities.
- [91] arXiv:2606.28289 (cross-list from cond-mat.stat-mech) [pdf, html, other]
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Title: Optimal parameterization of nonequilibrium generalized master equations from discrete-time experimental dataComments: 26 pages, 5 figuresSubjects: Statistical Mechanics (cond-mat.stat-mech); Biological Physics (physics.bio-ph); Chemical Physics (physics.chem-ph)
Kinetic analyses of experiments often require coarse-grained descriptions, but complex systems rarely conform to the widely used modeling assumptions of Markovianity and thermodynamic equilibrium. Memory is indeed a general and often inevitable consequence of coarse-graining. Markov state models (MSMs) are a popular choice of coarse-grained description, but require microstate assignments -- which are rarely experimentally tunable -- to macrostates that minimize memory. Generalized master equations (GMEs) circumvent this limitation of MSMs by explicitly capturing memory. However, GMEs are difficult to parameterize and usually formally approximate in the experimentally relevant discrete-time setting. Here we introduce a maximum-likelihood-based procedure to parameterize formally exact, physically feasible, discrete-time generalized master equations from experiments and simulations in and out of equilibrium. By adapting algorithms typically used in optimal transport, we construct physical-constraint-satisfying conditional-maximum-likelihood estimators of both exact Nakajima-Zwanzig memory kernels and time-convolutionless GME propagators in discrete time. Applying these estimators to three examples -- experimental recordings of Förster-resonance energy-transfer in an ion channel, experimental nanoparticle tracking of a processive molecular motor, and simulated folding of a benchmark protein domain -- we recover kinetic parameters including relaxation rates, irreversibilities, dwell times, and first-passage times. These results establish discrete-time GMEs as a physically and statistically principled alternative to MSMs for kinetic analyses of experimental and simulated biomolecular systems.
Cross submissions (showing 33 of 33 entries)
- [92] arXiv:2412.18032 (replaced) [pdf, html, other]
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Title: Major Space Weather Risks Identified via Coupled Physics-Engineering-Economic ModelingEdward J. Oughton, Dennies K. Bor, Robert Weigel, C. Trevor Gaunt, Ridvan Dogan, Liling Huang, Jeffrey J. Love, Michael WiltbergerSubjects: Geophysics (physics.geo-ph); General Economics (econ.GN); Systems and Control (eess.SY)
Space weather poses an important but under-quantified threat to society. While severe geomagnetic storms are recognized as potential global catastrophes, their socio-economic impacts remain poorly quantified. We present a novel physics-engineering-economic framework that links geophysical drivers to power grid geoelectric fields, transformer vulnerability, and macroeconomic consequences. Using the United States as an example, we estimate daily U.S. economic losses for a 250-year geomagnetic storm from transformer thermal heating of 2.04 billion USD (95 percent confidence interval: 1.86 to 2.22 billion USD), disrupting power for approximately 5.7 million people and 150,000 businesses. These estimates are conservative lower bounds, reflecting only transformer thermal heating effects and excluding voltage collapse, cascading failures, and restoration costs. The true societal risk is likely substantially higher. Nonetheless, the contribution is in providing the first nationwide end-to-end coupling from space physics to potential macroeconomic loss, with quantified uncertainties. Our results demonstrate that coupled socio-economic modeling of space weather is both feasible and essential, and the framework is scalable and transferable, offering a template for assessing space weather risk to critical infrastructure in other countries.
- [93] arXiv:2504.14724 (replaced) [pdf, html, other]
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Title: Parametrization of microbial survival models under UVC exposureSubjects: Medical Physics (physics.med-ph); Cell Behavior (q-bio.CB)
This work presents a unified framework for the parametrization and comparison of microbial survival models under UVC exposure. Four dose-response models - the single-target, multi-target, linear-quadratic, and two-stage decay models - are analyzed with respect to their mathematical structure, parameter identifiability, and biological interpretability, while ensuring physically meaningful parameter estimates. To address the limited size and lack of replication in published datasets, parameter uncertainty is quantified using a parametric bootstrap approach under multiplicative dose uncertainty. Model comparison combines goodness-of-fit in logarithmic survival space, the Akaike Information Criterion corrected for small samples, and identifiability considerations. Application to data for 32 microorganisms shows that no single model is universally optimal, highlighting that reliable model selection requires combining statistical performance with physical and biological consistency, and providing a robust basis for UVC survival analysis and disinfection modeling.
- [94] arXiv:2507.23527 (replaced) [pdf, html, other]
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Title: Holographic Strange Metals for Philosophers and PhysicistsComments: We dedicate this paper to the memory of Umut Gürsoy, who tragically passed away on 24 April 2025, during the last stages of the paper's completionJournal-ref: Found Phys 56, 8 (2026)Subjects: History and Philosophy of Physics (physics.hist-ph); Strongly Correlated Electrons (cond-mat.str-el); High Energy Physics - Theory (hep-th)
This paper introduces the physics and philosophy of strange metals, which are characterized by unusual electrical and thermal properties that deviate from conventional metallic behaviour. The anomalous strange-metal behaviour discussed here appears in the normal state of a copper-oxide high-temperature superconductor, and it cannot be described using standard condensed-matter physics. Currently, it can only be described through a holographic dual, viz.~a four-dimensional black hole in anti-de Sitter spacetime. This paper first introduces the theory of, and specific experiments carried out on, strange metals. Then it discusses a number of philosophical questions that strange metals open up regarding the experimental evidence for holography and its realist interpretation. Strange metals invert the explanatory arrows, in that usual holographic arguments are seen as giving explanations of the bulk quantum-gravity theory from the boundary. By contrast, the aim here is, by using holography, to explain the experimentally discovered and anomalous properties of strange metals.
- [95] arXiv:2508.20303 (replaced) [pdf, html, other]
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Title: Efficient ion re-acceleration in laboratory-produced interpenetrating collisionless shocksW. Yao, I. Cohen, P. Suarez Gerona, H. Ahmed, A.F.A. Bott, S. N. Chen, M. Cook, R. Lelièvre, P. Martin, T. Waltenspiel, P. Antici, J. Béard, M. Borghesi, D. Caprioli, A. Ciardi, E. d'Humières, M. François, L. Gremillet, A. Marcowith, M. Miceli, T. Seebaruth, S. Orlando, J. FuchsSubjects: Plasma Physics (physics.plasm-ph); High Energy Astrophysical Phenomena (astro-ph.HE)
Although the origin of cosmic rays (CRs) remains an open question, collisionless magnetized shock waves are widely regarded as key sites for particle acceleration. Recent theories further suggest that shock-shock collisions in stellar clusters could provide the additional acceleration needed to explain the observed high-energy CR spectrum. Here, we investigate this hypothesis through a laser-based experiment that creates magnetized plasma conditions similar to astrophysical environments. Our results demonstrate that interpenetrating collisionless shocks can significantly boost the energy of ambient protons previously energized by the individual shocks, while also improving the overall acceleration efficiency. Numerical kinetic simulations corroborate these findings, revealing that protons are reaccelerated via their bouncing motion in the convective electric fields of the colliding magnetized flows. By allowing to highly energize ambient protons, our novel colliding-shock platform opens the prospect to test the long-discussed mechanism of diffusive shock acceleration in a controlled laboratory setting.
- [96] arXiv:2509.11721 (replaced) [pdf, html, other]
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Title: Experimental Investigation of Time Series Classification using a Self-Pulsing Microring Resonator NetworkComments: 20 pages, 7 figures Accepted ManuscriptSubjects: Optics (physics.optics)
Photonic neuromorphic computing offers compelling advantages in power efficiency and parallel processing, but often falls short in realizing scalable nonlinearity and long-term memory. These limitations can be overcome by silicon microring resonator (MRR) networks. These integrated photonic circuits enable compact, high-throughput neuromorphic computing by simultaneously exploiting spatial, temporal, and wavelength dimensions. This work provides an in-depth study of of MRR networks for photonics-based machine learning (ML). We investigate the system's effectiveness on two widely used image classification benchmarks, MNIST and Fashion-MNIST, by encoding images directly into time sequences. In particular, we enhance the computational performance of a linear readout classifier within the reservoir computing paradigm through the strategic use of multiple physical output ports, diverse laser wavelengths, and varied input power levels. Moreover, we explore a single-pixel classification setting, where inference does not require digital memory, thanks to the inherent memory and parallelism of our MRR network.
- [97] arXiv:2510.21971 (replaced) [pdf, html, other]
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Title: Revisiting the phenomenon of bouncing of inertial particles crossing density stratified interfacesSubjects: Fluid Dynamics (physics.flu-dyn)
Inertial spheres settling through sharp density interfaces can arrest, reverse direction, and resume descent, a phenomenon known as bouncing. Using synchronized particle image velocimetry and tracking in water-salt and water-glycerol stratifications, we demonstrate that bouncing is the dynamic response of a coupled sphere-fluid composite. As the sphere crosses the interface, it entrains a boundary layer of lighter fluid, creating a transient buoyant wake.
We formalize this mechanism into a phenomenological dynamic model that couples the momentum of the sphere with the entrainment and detachment of the wake. Evaluating the stationary points of this system yields a criterion that classifies trajectory archetypes (smooth crossing, deep minima, and bouncing) across different fluid regimes. We identify a dual role of viscosity, which is often overlooked by density-only models: it acts kinematically to thicken the boundary layer and increase the entrained wake volume, and dynamically to alter the drag-to-weight balance.
Furthermore, we describe the spatial dynamics of the crossing: inertia-dominated spheres penetrate further into the lower fluid before arresting due to a longer wake-detachment length, whereas buoyancy-dominated spheres arrest closer to the interface. Finally, we show that the retention time is governed by the buoyancy-driven detachment of the entrained film. By normalizing the measured retention times with a characteristic detachment timescale, we collapse the data from different viscosity regimes onto a single curve. These physical insights allow the prediction of trajectory archetype, deceleration depth, and retention time from bulk properties. - [98] arXiv:2512.06245 (replaced) [pdf, html, other]
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Title: How Withheld Punishment Enables Authoritarian Persistence: An Evolutionary Dynamics ApproachSubjects: Physics and Society (physics.soc-ph); Adaptation and Self-Organizing Systems (nlin.AO); Populations and Evolution (q-bio.PE)
Democratic backsliding is often framed as a contest between pro-democratic defenders and anti-institutional norm-breakers. That framing can miss a third behavior, a public that withholds punishment from norm-breakers while penalizing those who confront them. We study a minimal three-strategy evolutionary game, with institutional defenders, anti-institutional disruptors, and this non-punishing public evolving under replicator dynamics. We grant defenders a head-to-head advantage over disruptors and ask whether it guarantees their long-run success. It does not. Two payoff regimes, differing only in how the public and disruptors interact, produce two failure modes. In an exploitation regime, the public is harmed by disruptors yet withholds sanction, so the three strategies exhibit cyclic dominance. When the losses around the cycle outweigh the gains, every interior trajectory approaches a boundary heteroclinic cycle in which disruptors repeatedly resurge. In an accommodation regime, the public and disruptors each gain from their interaction. When the public's gain is large enough, every interior trajectory converges to a stable public-disruptor coalition that excludes defenders. A pro-democratic advantage is therefore not enough. Weak sanction and penalized confrontation can leave anti-institutional disruption recurring or entrenched.
- [99] arXiv:2512.18769 (replaced) [pdf, html, other]
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Title: Quantitative mobile gamma-ray spectrometry through Bayesian inferenceComments: 25 pages, 6 figures, 1 ancillary fileSubjects: Instrumentation and Detectors (physics.ins-det); Applied Physics (physics.app-ph); Computational Physics (physics.comp-ph); Data Analysis, Statistics and Probability (physics.data-an); Geophysics (physics.geo-ph)
Accurate quantitative mapping of gamma-ray sources is critical for applications ranging from radiological emergency response and environmental monitoring to nuclear security and deep space exploration. Here, we show that integrating high-fidelity, platform-dynamic Monte Carlo simulations and Bayesian inference with mobile gamma-ray spectrometry enables rapid and accurate inference of the source mixture, associated source activities, and source locations for both distributed and point-like gamma-ray sources. Validated against laboratory and field assays, our framework quantifies anthropogenic gamma-ray sources that conventional methods cannot resolve in $1\,$s with $\sim\!\!1\,\%$ error. The developed method marks a critical advance in quantitative gamma-ray sensing, enabling improved radiological situational awareness, enhanced terrestrial geophysical and geochemical mapping, as well as more robust constraints on radionuclide abundances on extraterrestrial bodies across the Solar System.
- [100] arXiv:2512.19196 (replaced) [pdf, html, other]
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Title: Adaptive Probability Flow Residual Minimization for High-Dimensional Fokker-Planck EquationsSubjects: Computational Physics (physics.comp-ph); Machine Learning (cs.LG); Numerical Analysis (math.NA)
Solving high-dimensional Fokker-Planck (FP) equations remains a challenging problem in computational physics and stochastic dynamics, due to the curse of dimensionality, unbounded domains, and complex probability landscapes. In this work, we propose an adaptive probability flow residual minimization (A-PFRM) method for this problem. The second-order FP equation is reformulated as an equivalent first-order continuity equation associated with the probability flow ordinary differential equation, based on which a loss function is constructed to train neural network approximations without Hessian computation. To further improve the computational efficiency, the Hutchinson trace estimator is applied to compute the divergence in the corresponding score function, such that the training time can be dimension-independent on GPUs. Adaptive sampling strategies are employed to generate the collocation points, and our analysis shows that the Kullback-Leibler divergence between our A-PFRM approximation and the exact solution is bounded by the residual loss weighted by the estimated density function. Numerical experiments are presented to demonstrate the performance of A-PFRM, which include Ornstein-Uhlenbeck (OU) processes problems, Brownian motions with time-varying diffusion, and Geometric OU processes featuring non-Gaussian solutions up to one hundred dimensions.
- [101] arXiv:2512.19859 (replaced) [pdf, html, other]
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Title: An atom chip interferometerComments: 14 pages, 10 figuresJournal-ref: Phys. Rev. A 113, 063325, 2026Subjects: Atomic Physics (physics.atom-ph)
We have realized an interferometer using a thermal cloud of magnetically trapped rubidium 87 atoms on a chip. The interferometer resembles a Ramsey interferometer with a state selective spatial splitting of the two internal states as proposed in [M. Ammar, and al., Phys. Rev. A, 91, 053623]. The splitting is effected by microwave fields from two on-chip waveguides while the atoms remain magnetically trapped. The inferred maximum separation is $1.2\pm 0.1~\mu$m. We observe interference fringes with a contrast around 8\% limited by velocity difference of the two interferometer states when we close the interferometer. We develop a model describing this contrast decay.
- [102] arXiv:2601.14632 (replaced) [pdf, html, other]
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Title: The missing links: Evaluating contact tracing with incomplete data in large metropolitan areas during an epidemicComments: 14 pages, 8 figures, 1 tableSubjects: Physics and Society (physics.soc-ph); Statistical Mechanics (cond-mat.stat-mech); Populations and Evolution (q-bio.PE)
Contact tracing (CT) is a frontline measure against emerging epidemics, yet in practice it is never complete. The quantitative impact of missing information -- such as untraced cases or unnotified contacts -- on the effectiveness of CT remains insufficiently understood. Using a stochastic agent-based model with sociodemographics from metropolitan areas in South Korea, we simulate how different forms of information loss affect epidemic spreading dynamics. We construct information-loss scenarios based on two types: infector-omission (IO), the omission of infected individuals from the tracing process, and contact-omission (CO), the omission of specific contact events even when the infected individuals themselves are identified. The sensitivity of epidemic dynamics to increasing omission rates differs markedly between the two types: IO produces substantially stronger and more abrupt changes in transmission structure and epidemic outcomes, whereas CO produces more gradual effects. Notably, CT effectiveness breaks down beyond a city-specific threshold -- an IO rate of approximately 4% in Seoul but about 10% in less populous Busan -- underscoring that CT strategies must be tailored to regional population and mobility structure. Both IO and CO scenarios also lead to an increase in the transmission network diameter as information loss grows, indicating that a small network diameter reflects effective contact tracing that limits the depth of transmission chains. Collectively, our results offer threshold estimates and practical guidance for designing robust CT systems in the real world.
- [103] arXiv:2601.17328 (replaced) [pdf, html, other]
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Title: Quantum field theory approach for multistage chemical kinetics in liquidsComments: Main article: 29 pages, 9 figures; Supplementary: 15 pages, 1 figure; ResubmissionSubjects: Chemical Physics (physics.chem-ph); Other Condensed Matter (cond-mat.other); Statistical Mechanics (cond-mat.stat-mech)
Reaction-diffusion processes play an important role in a variety of physical, chemical, and biological systems. Conventionally, the kinetics of these processes are described by the law of mass action. However, there are various cases where these equations are insufficient. A fundamental challenge lies in accurately accounting for the microscopic correlations that inevitably arise in bimolecular reactions. While approaches to describe microscopic correlations in many specific cases exist, no general theory for multistage reactions has been established. In this article, we apply the quantum field theory approach to derive kinetic equations for general multistage reactive systems termed CMET (complete modified encounter theory). CMET can be formulated as a set of coupled partial differential equations that can be easily integrated numerically, thereby serving as a versatile tool for investigating reaction-diffusion processes. Across multiple case studies, we demonstrated that CMET reproduces the kinetics predicted by many other theories within their respective scopes of applicability.
- [104] arXiv:2603.09658 (replaced) [pdf, html, other]
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Title: Immiscible two-phase flow in porous media: a statistical mechanics approachComments: 28 pages, 7 figures. arXiv admin note: text overlap with arXiv:2501.04468Subjects: Fluid Dynamics (physics.flu-dyn)
The central problem in the physics of immiscible two-phase flow in porous media is to find a proper description of the flow at scales large enough so that the medium may be regarded as a continuum: the scale-up problem. So far, the only workable approach to the multiphase flow scale-up problem has been a set of phenomenological equations that have obvious weaknesses. Attempts at going beyond this relative permeability theory have so far not led to practical applications due to exploding complexity. Edwin T. Jaynes proposed in the fifties a generalization of statistical mechanics to non-thermal systems based on the information theoretical entropy of Shannon. This approach is used to construct a description of immiscible two-phase flow in porous media at the continuum scales, which is directly related to the physics at the pore scale, and at a level of complexity that is manageable. The approach leads to a thermodynamics-like formalism at the continuum scale with all the relations between variables that "normal" thermodynamics has to offer. New emergent variables appear. Among these, the co-moving velocity stands out as a key variable with implications for ordinary thermodynamics. We present here a short review of this approach.
- [105] arXiv:2603.17049 (replaced) [pdf, html, other]
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Title: Attractor-Keyed MemoryComments: 7 pages, 2 figures; Supplementary Materials is available as this https URLSubjects: Optics (physics.optics); Disordered Systems and Neural Networks (cond-mat.dis-nn); Emerging Technologies (cs.ET); Information Theory (cs.IT); Neural and Evolutionary Computing (cs.NE)
Physical selectors (lasers choosing a mode, Ising machines settling on a ground state, condensates occupying a spin state) produce high-dimensional signatures at the moment of decision: full field amplitudes, multimode interference patterns, or scattering responses. These signatures are richer than the winner's index, yet they are routinely discarded. We show that when the signatures are repeatable across trials (stereotyped) and linearly independent across routes, a single linear decoder compiled from calibration data maps them to arbitrary payloads, merging selection and memory access into one event and eliminating the fetch that dominates latency and energy in sparse routing architectures. The construction requires one SVD of measured device responses, which certifies capability and bounds worst-case error for any downstream payload before the task is chosen. Runtime error separates into two independently diagnosable channels, decoding fidelity (controlled by dictionary conditioning $\sigma_{\min}(\Phi)$) and routing reliability (controlled by the margin-to-noise ratio $\Delta/T_{\mathrm{eff}}$), each with a distinct physical origin and targeted remedy. We derive the full error decomposition, give Ising-machine selector constructions, and validate the predicted scalings on synthetic speckle-signature simulations across three measurement modalities. No hardware demonstration exists; we provide a falsifiable four-step experimental protocol specifying what a first experiment must measure. Whether real device signatures satisfy stereotypy is the central open question.
- [106] arXiv:2605.00511 (replaced) [pdf, other]
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Title: Pre-CAT: A web-based, graphical user-interface toolbox for preclinical CEST-MRI data processing and analysisJonah Weigand-Whittier, Samuel Rubin, Cindy Ayala, Mark Velasquez, Nikita Vladimirov, Hadas Avraham, Or Perlman, M. Roselle Abraham, Moriel H. VandsburgerSubjects: Medical Physics (physics.med-ph)
Purpose: As interest in CEST-MRI grows, particularly in the preclinical setting, the necessity for standardized and easy-to-use acquisition and data analysis pipelines has become apparent. While vendors have increasingly introduced support for CEST acquisitions on both clinical and preclinical hardware, image post-processing and analysis pipelines remain siloed based on privately developed code. We aim to develop an easy-to-use, open-source graphical user interface toolbox for preclinical CEST-MRI data analysis (Preclinical CEST-MRI Analysis Tool; Pre-CAT), supporting multiple acquisition types, organ systems, and CEST contrast mechanisms. Methods: Pre-CAT was developed in Python and utilizes the Numpy, Scipy, and Matplotlib libraries for data analysis and plotting. Inbuilt data processing steps include image loading, reconstruction, post-processing, and segmentation. Pre-CAT also supports data analysis for QUESP, CEST-MRF, and field mapping experiments using consensus protocols and methods. Pre-CAT's web interface and GUI were developed using Streamlit, an open-source Python framework. Pre-CAT is hosted and accessible online and can be downloaded for local installation to complete the data analysis pipeline in roughly one minute using modern hardware. Results: Pre-CAT analysis pipelines for Z-spectroscopy, CEST-MRF, and quantitative CEST (QUESP/QUEST) are demonstrated. Conclusion: With the introduction of Pre-CAT, we aim to standardize the preclinical CEST-MRI data analysis pipeline, fostering collaboration across research sites and reducing methodological redundancy. Pre-CAT is open-source and relatively modular, encouraging the addition of new methods and protocols.
- [107] arXiv:2605.11379 (replaced) [pdf, html, other]
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Title: Bridging the Gap between Extreme Environments and Precision Measurements: Recent Progress in Megagauss PhysicsComments: 68 pages, 55 figures, review article, Published in Applied Sciences (MDPI)Journal-ref: AppliedPhys 2026, 2(2), 6Subjects: Instrumentation and Detectors (physics.ins-det); Materials Science (cond-mat.mtrl-sci)
Ultrastrong magnetic fields, ranging from 100~T to 1,000~T, are generated exclusively by destructive pulsed magnets. While various generation methods exist, this review focuses on the Single-Turn Coil (STC) and Electromagnetic Flux Compression (EMFC) techniques, which provide optimal environments for high-precision measurements in materials science. First, we present recent technological breakthroughs in the EMFC method that have successfully achieved fields exceeding 1,000~T. We then describe specialized measurement infrastructures for magneto-optics, magnetization, and magneto-transport, highlighting the development of miniaturized all-plastic cryostats and custom sample holders designed for the dual extremes of cryogenic temperatures and megagauss fields. Representative physical phenomena revealed through these techniques are discussed, including quantum phase transitions in frustrated magnets, Aharonov--Bohm effects in carbon nanotubes, and semiconductor-to-metal transitions in strongly correlated systems. Furthermore, we address emerging measurement platforms such as magnetostriction, specific heat, and ultrasound velocity. Throughout this review, we emphasize the instrumentation and experimental refinements that ensure reliable data acquisition in the ultrastrong pulsed field regime.
- [108] arXiv:2605.17549 (replaced) [pdf, other]
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Title: van der Waals Crystal Anisotropy Controls Dual-Channel Refractive Index Sensing in a TiO$_{2}$/$α$-MoO$_{3}$ Nanobar MetasurfaceSubjects: Optics (physics.optics)
Filling the gap of a TiO$_2$ nanobar-pair metasurface with $\alpha$-MoO$_3$, a biaxial orthorhombic crystal, produces two high-$Q$ Fano resonances with asymmetric quality factors: $Q_{\mathrm{TE}}=87$ at 863.3 nm and $Q_{\mathrm{TM}}=31$ at 960.1 nm, separated by 97 nm. The same device with amorphous or crystalline Sb$_2$S$_3$, both isotropic, yields comparable quality factors in both channels, confirming that the $Q$-ratio asymmetry originates in the biaxial crystal symmetry of $\alpha$-MoO$_3$ rather than the index magnitude of the fill. The two inequivalent permittivity contrasts of the orthorhombic lattice ($\Delta\varepsilon_{\beta\gamma}=0.983$ for TE, $\Delta\varepsilon_{\alpha\gamma}=2.420$ for TM) place each channel at a different point on the $Q\propto(\Delta\varepsilon)^{-2}$ scaling curve, consistent with quasi-BIC mode character. The TE channel delivers sensitivity $S=155.3$ nm RIU$^{-1}$, figure of merit 15.71 RIU$^{-1}$, and limit of detection $6.44\times10^{-5}$ RIU. TM delivers $S=139.1$ nm RIU$^{-1}$, figure of merit 4.44 RIU$^{-1}$, and limit of detection $7.19\times10^{-5}$ RIU. Simultaneous readout produces a polarization fingerprint with isotropic slope 0.896, deviations from which encode analyte optical anisotropy.
- [109] arXiv:2605.19067 (replaced) [pdf, html, other]
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Title: Kinetic theory of the Thermal Farley-Buneman Instability in the E-region ionosphereComments: 72 pages, 1 figureSubjects: Plasma Physics (physics.plasm-ph)
This paper develops a fully kinetic linear theory of the thermal Farley-Buneman instability (TFBI) in the E-region ionosphere with unmagnetized ions. The TFBI combines spatially uniform E-region plasma instabilities, such as the Farley-Buneman instability (FBI), ion thermal instability (ITI), and electron thermal instability (ETI). Similar collision-dominated plasma processes can also occur in the solar and stellar chromospheres, as well as in other planetary atmospheres. For the first time in the theory of the FBI-related processes, the kinetic description of ions includes the driving electric field, resulting in automatic inclusion of the ITI. This analytic theory has produced a comprehensive linear wave dispersion relation. It is remarkable that, similarly to the oversimplified earlier ion-kinetic studies, this much more general kinetic dispersion relation involves only elementary functions and the standard plasma dispersion function (albeit of several different arguments). This new theory is limited to plasma waves with the frequencies of the order, or larger than, the ion-neutral collision frequency. This inherently kinetic frequency range is of importance for accurate interpretation of radar signals scattered from relatively high E-region altitudes, but at altitudes where ions are unmagnetized (mostly, below 110 km).
- [110] arXiv:2606.12457 (replaced) [pdf, html, other]
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Title: Quantum Entanglement Beyond Kinematics: A Dynamical Hypothesis in (3,2)-Dimensional SpacetimeComments: 35 pages, 1 figure. A small computational error in Section IIIA has been corrected without affecting its conclusion; the bipartite construction in Section VIB has been revised to restrict to Schmidt-diagonal states; a comment on Eq.(103) is addedSubjects: General Physics (physics.gen-ph)
Quantum entanglement produces nonlocal correlations for which no local dynamical account is known. In Ref.[1] we proposed that these correlations are mediated through an extra temporal dimension and introduced a $(3,2)$-dimensional spacetime framework on a phenomenological basis; the present paper derives that framework from the bulk geometry. A single extra spatial dimension admits no effective superluminal shortcut on the brane, this rules it out as a candidate mediator and motivates the extra-time setting. Within the warped-product metric ansatz the five-dimensional vacuum Einstein equations fix the warp factor uniquely, leaving no freedom in the geometry once $\mathbb{Z}_2$ symmetry is imposed. A massless bulk field $\mathscr{X}_a(\mathbf{x},t,\tau)$, sourced on the brane by the preparation event and by the measurement interactions, propagates causally through the extra-time dimension; equal-time correlations at arbitrarily large brane separation arise via the $E=0$ null geodesic family, without admitting controllable superluminal signaling. The propagation time and crossed ratios of Ref.~\cite{PRR}, previously postulated, emerge here from the null geodesic kinematics. The Bohm--Bub collapse framework is extended to a bipartite entangled system by replacing the abstract hidden vector with the brane-projected bulk field $\mathscr{X}_a$. At fixed contextual microstate $\lambda$ collapse is deterministic; Born statistics follow upon averaging over an equivariant ensemble. When the framework is extended to two independent Bell pairs, the bulk field sourced by one pair reaches the detectors of the other and induces a cross-pair correlation scaling as the square of the intra-pair to inter-pair separation ratio, a concrete falsifiable prediction with no counterpart in standard quantum mechanics, accessible with existing photonic Bell-test technology.
- [111] arXiv:2606.16324 (replaced) [pdf, html, other]
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Title: Integrated tunable mid-infrared electro-optic frequency comb generator based on nonlinear conversionSubjects: Optics (physics.optics)
Mid-infrared frequency combs enable highly selective and sensitive molecular spectroscopy by leveraging the strong vibrational transitions in this spectral region. Among these, there is a particular need for compact, tunable sources with electronic control over comb parameters for integrated sensing platforms. In this work, we demonstrate a mid-infrared electro-optic frequency comb source based on nonlinear frequency conversion in thin film lithium niobate. The system combines a near-infrared pump, amplitude-modulated using an integrated Mach-Zehnder modulator for lock-in detection, with a telecom-band electro-optic comb generated via a double-pass phase modulation scheme. Mid-infrared comb generation is achieved through difference frequency generation in a periodically poled waveguide. By tuning the telecom seed laser and the chip temperature, we obtain mid-infrared combs with a bandwidth of approximately 6 nm and center wavelength tunability of over 200 nm. The comb free spectral range is directly controlled via the applied radio-frequency modulation. Operation across multiple integrated photonic circuits reaching wavelengths up to 3.7 $\mu$m is demonstrated. Furthermore, dual-tone EO comb generation in the mid-infrared is realized. To our knowledge, this is the first integrated mid-infrared electro-optic comb source offering independent electronic control of both center wavelength and comb spacing.
- [112] arXiv:2606.26912 (replaced) [pdf, html, other]
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Title: A Givens-exchange ansatz for molecular variational eigensolversAzadeh Alavi, Fatemeh Kouchmeshki, Muhammad Usman, Yongli Ren, Ke Deng, Hossein Akhoundi, Abdolrahman AlaviComments: 18 pages, 3 figuresSubjects: Chemical Physics (physics.chem-ph); Quantum Physics (quant-ph)
Molecular ground-state energies help determine conformer rankings, reaction energetics, and electronic effects in computational drug discovery, but accurate calculations become difficult when strong correlation or large active spaces are important. Variational quantum eigensolvers estimate these energies by optimizing a parameterized quantum state, making ansatz design central to both accuracy and cost. We study a fixed-topology Givens-exchange ansatz that avoids architecture search. The circuit starts from the computational-basis state with the lowest diagonal Hamiltonian expectation and applies local RY rotations with two ordered all-pair Givens exchange blocks. Parameters are optimized using Hamiltonian expectation values, while exact diagonalization is used only after optimization to compute errors and fidelities. Across six fixed seeds, coefficient-verified LiH-6 and H2O-8 Hamiltonians, together with a BeH2-6 public-specification candidate, are chemically accurate in every run. The corresponding six-seed mean errors are 0.000000124 Hartree, equivalent to 0.000124 milli-Hartree; 0.000128558 Hartree, equivalent to 0.128558 milli-Hartree; and 0.000002152 Hartree, equivalent to 0.002152 milli-Hartree, respectively. On LiH-6 and H2O-8, these mean errors are lower than the published point errors of the compared quantum-architecture-search methods, while the ansatz uses a larger pre-compilation macro budget. The method is therefore an accurate, reproducible, and search-free reference template for molecular variational eigensolvers.
- [113] arXiv:2406.19554 (replaced) [pdf, html, other]
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Title: A Network-Based Measure of Cosponsorship Influence on Bill Passing in the United States House of RepresentativesComments: 'Conclusions and Discussion' revised to have an improved discussion of our work's limitationsSubjects: Social and Information Networks (cs.SI); Physics and Society (physics.soc-ph)
Each year, the United States Congress considers thousands of legislative proposals to select bills to present to the US President to sign into law. Naturally, the decision processes of members of Congress are subject to peer influence. In this paper, we examine the effect on bill passage of accrued influence between US Congress members in the US House of Representatives. We explore how the influence of a bill's cosponsors affects the bill's outcome (specifically, whether or not it passes in the House). We define a notion of influence by analyzing the structure of a network that we construct using cosponsorship dynamics. We award `influence' between a pair of Congress members when they cosponsor a bill that achieves some amount of legislative success. We find that properties of the bill cosponsorship network can be a useful signal to examine influence in Congress; they help explain why some bills pass and others fail. We compare our measure of influence to off-the-shelf centrality measures and conclude that our influence measure is more indicative of bill passage.
- [114] arXiv:2502.04598 (replaced) [pdf, html, other]
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Title: Arbitrary state preparation in quantum harmonic oscillators using neural networksSubjects: Quantum Physics (quant-ph); Optics (physics.optics)
Preparing quantum states is a fundamental task in various quantum algorithms. In particular, state preparation in quantum harmonic oscillators (HOs) is crucial for the manipulation of qudits and the implementation of high-dimensional algorithms. In this work, we develop a general methodology for quantum state preparation in an HO coupled to an auxiliary qubit, guaranteeing that any target state is physically preparable. Both the qubit and the HO are driven by two lasers with time-dependent phase modulation. The modulation times and phase values are generated by a neural network whose input is the desired target state. In contrast to conventional quantum control approaches, this framework eliminates the need for per-instance optimization of the control protocol. Instead, the control parameters required to prepare an arbitrary quantum state of the HO are obtained directly from a single forward pass through the neural network. Specifically, we present results for preparing arbitrary qubit, qutrit, and qudit (n=4) states in the HO, achieving average fidelities of 99.99%, 99.5%, and 98.9%, respectively, across random target states.
- [115] arXiv:2503.13922 (replaced) [pdf, html, other]
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Title: Existence and Smoothing Effects for a Degenerate Diffusion from Plasma Instability TheorySubjects: Analysis of PDEs (math.AP); Mathematical Physics (math-ph); Plasma Physics (physics.plasm-ph)
We prove existence and positive-time smoothing of weak solutions to the parabolic Cauchy--Dirichlet problem $\partial_{t} u - \rho_\lambda(x) u \partial_{x}^2 u = \rho_{\lambda}(x) g(x) u$ on the half-line $(0, \infty)$. This problem arises from a system of equations known as the quasilinear theory of plasma waves. We construct weak solutions from weighted $L^p$ initial data ($p < \infty$) and bounded forcing $\rho_{\lambda} g \in L^\infty$, a substantially broader data class than previously considered. We identify a parabolic smoothing mechanism for these solutions: a Bénilan--Crandall inequality which provides a one-sided lower bound on $\partial_{t} u$. Driven by this inequality, our solutions become jointly Hölder in space and time and locally Lipschitz in space at positive times. Explicit examples show this spatial regularity is sharp. To our knowledge, this parabolic smoothing from discontinuous data has not previously been established within the family of degenerate quasilinear nondivergence equations with prototype $\partial_{t} u - u \Delta u = 0$. The Bénilan--Crandall inequality is also new in this setting, and its proof by time-scaling extends formally to other equations of this family.
- [116] arXiv:2507.10005 (replaced) [pdf, html, other]
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Title: Effects of relational graph modularity and depth on the learning performance of neural networksComments: 12 pages, 7 figuresSubjects: Machine Learning (cs.LG); Statistical Mechanics (cond-mat.stat-mech); Neural and Evolutionary Computing (cs.NE); Computational Physics (physics.comp-ph)
In recent years, graph-based machine learning techniques, such as reinforcement learning and graph neural networks, have garnered significant attention. While some recent studies have started to explore the relationship between the graph structure of neural networks and their predictive performance, they often limit themselves to a narrow range of model networks, particularly lacking mesoscale structures such as communities. Our work advances this area by conducting a more comprehensive investigation, incorporating realistic network structures characterized by heterogeneous degree distributions and community structures, which are typical characteristics of many real networks. These community structures offer a nuanced perspective on network architecture. Our analysis employs model networks such as random and scale-free networks, alongside a comparison with a biological neural network and its subsets for more detailed analysis. We examine the impact of these structural attributes on the performance of image classification tasks. Our findings reveal that structural properties do affect performance to some extent. Specifically, networks featuring coherent, densely interconnected communities demonstrate enhanced learning capabilities. Crucially, we find that this advantage is depth-dependent: extending the architecture to eight layers reverses the effect entirely. This comparison with the biological neural network emphasizes the relevance of our findings to real-world structures, suggesting an intriguing connection worth further exploration. This study contributes meaningfully to network science and machine learning, providing insights that could inspire the design of more biologically informed neural networks.
- [117] arXiv:2507.17831 (replaced) [pdf, html, other]
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Title: On Focusing Statistical Power for Searches and Measurements in Particle PhysicsComments: 16 pages, 10 figures, 3 tables (European Physical Journal C (2026) accepted for publication)Subjects: High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Experiment (hep-ex); Data Analysis, Statistics and Probability (physics.data-an); Applications (stat.AP); Methodology (stat.ME)
Particle physics experiments rely on the (generalised) likelihood ratio test (LRT) for searches and measurements, which consist of composite hypothesis tests. However, this test is not guaranteed to be optimal, as the Neyman-Pearson lemma pertains only to simple hypothesis tests. Any choice of test statistic thus implicitly determines how statistical power varies across the parameter space. An improvement in the core statistical testing methodology for general settings with composite tests would have widespread ramifications across experiments. We discuss an alternate test statistic that provides the data analyzer an ability to focus the power of the test on physics-motivated regions of the parameter space. We demonstrate the improvement from this technique compared to the LRT on a Higgs $\rightarrow\tau\tau$ dataset simulated by the ATLAS experiment and a dark matter dataset inspired by the LZ experiment. We also employ machine learning to efficiently calibrate critical values for a family of tests, which are then inverted to obtain statistically valid confidence intervals.
- [118] arXiv:2509.14320 (replaced) [pdf, html, other]
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Title: Quantum Semiconductor Heterostructures for meV Axion Dark Matter DetectionJaanita Mehrani, Tao Xu, Andrey Baydin, Michael J. Manfra, Henry O. Everitt, Andrew J. Long, Kuver Sinha, Junichiro Kono, Shengxi HuangComments: Matches version published in PRL. 9+18 pages, 6+12 figuresJournal-ref: Phys. Rev. Lett. 136, 241001 (2026)Subjects: High Energy Physics - Phenomenology (hep-ph); Cosmology and Nongalactic Astrophysics (astro-ph.CO); Mesoscale and Nanoscale Physics (cond-mat.mes-hall); Instrumentation and Detectors (physics.ins-det); Quantum Physics (quant-ph)
We propose a novel strategy and a new class of detectors for the direct detection of axion dark matter in the meV mass range, based on resonantly enhanced axion-photon conversion through the inverse Primakoff effect in engineered radiometers composed of quantum semiconductor heterostructures. Semiconductor-Quantum-Well Axion Radiometer Experiments (SQWAREs) are multiple quantum well structures forming magnetoplasmonic cavities, containing high-mobility two-dimensional electron gases, realizing tunable epsilon-near-zero resonances in the terahertz frequency range. By controlling the orientation of the cavity within a strong external magnetic field, both the resonance frequency and the axion-induced current are optimized $\it{in\,situ}$, enabling efficient scanning across a broad mass range without the need for complex mechanical adjustments. The axion-induced electromagnetic signal radiatively emitted from the cavity is then detected by a photodetector. We present the theoretical basis for resonant enhancement, detail the experimental design and benchmarks through extensive simulations, project the sensitivity of an example SQWARE for several realistic configurations, and demonstrate the modularity and flexibility of the design to fit reasonably with any lab's existing capabilities and target unique axion mass ranges. Our results demonstrate that the SQWAREs can probe the well-motivated quantum chromodynamics axion parameter space and close a critical gap in direct searches at meV masses.
- [119] arXiv:2510.25731 (replaced) [pdf, html, other]
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Title: LieSolver: PDE-Constrained Learning for IBVPs via Lie SymmetriesRené P. Klausen, Ivan Timofeev, Jonas Naujoks, Johannes Frank, Thomas Wiegand, Sebastian Lapuschkin, Wojciech SamekComments: Accepted at the Workshop on AI for Physics @ ICML 2026 (non-archival). 27 pages, 27 figures. Code: this https URL. v2: updated to camera-ready workshop versionSubjects: Machine Learning (cs.LG); Artificial Intelligence (cs.AI); Numerical Analysis (math.NA); Computational Physics (physics.comp-ph)
Initial-boundary value problems (IBVPs) provide the essential framework for modelling a wide range of phenomena in physics and engineering. We introduce a novel method for efficiently solving IBVPs using Lie symmetries to enforce the associated partial differential equation (PDE) exactly by construction. By leveraging symmetry transformations, our model embeds the underlying physical laws and learns the solution solely from initial and boundary data. Consequently, the boundary loss directly quantifies domain-wide error, enabling rigorous error estimation for well-posed IBVPs. We implement LieSolver and demonstrate its application to linear homogeneous PDEs, showing that it outperforms physics-informed neural networks (PINNs) in both speed and accuracy while yielding compact models. Overall, our approach significantly enhances the efficiency and reliability of predictions for PDE-constrained problems.
- [120] arXiv:2601.13236 (replaced) [pdf, html, other]
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Title: Pixelwise Uncertainty Quantification of Accelerated MRI ReconstructionComments: 12 pages, 8 figues, 2 tablesSubjects: Image and Video Processing (eess.IV); Artificial Intelligence (cs.AI); Medical Physics (physics.med-ph)
Parallel imaging techniques reduce magnetic resonance imaging (MRI) scan time but image quality degrades as the acceleration factor increases. In clinical practice, conservative acceleration factors are chosen because no mechanism exists to automatically assess the diagnostic quality of undersampled reconstructions. This work introduces a general framework for pixel-wise uncertainty quantification in parallel MRI reconstructions, enabling automatic identification of unreliable regions without access to any ground-truth reference image. Our method integrates conformal quantile regression with image reconstruction methods to estimate statistically rigorous pixel-wise uncertainty intervals. We trained and evaluated our model on Cartesian undersampled brain and knee data obtained from the fastMRI dataset using acceleration factors ranging from 2 to 10. An end-to-end Variational Network was used for image reconstruction. Quantitative experiments demonstrate strong agreement between predicted uncertainty maps and true reconstruction error. Using our method, the corresponding Pearson correlation coefficient was higher than 90% at acceleration levels at and above four-fold; whereas it dropped to less than 70% when the uncertainty was computed using a simpler a heuristic notion (magnitude of the residual). Qualitative examples further show the uncertainty maps based on quantile regression capture the magnitude and spatial distribution of reconstruction errors across acceleration factors, with regions of elevated uncertainty aligning with pathologies and artifacts. The proposed framework enables evaluation of reconstruction quality without access to fully-sampled ground-truth reference images. It represents a step toward adaptive MRI acquisition protocols that may be able to dynamically balance scan time and diagnostic reliability.
- [121] arXiv:2606.05517 (replaced) [pdf, html, other]
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Title: A universal and efficient hybrid digital-analog fermionic quantum simulatorComments: 29 pages, 12 figures, 8 appendicesSubjects: Quantum Gases (cond-mat.quant-gas); Strongly Correlated Electrons (cond-mat.str-el); Atomic Physics (physics.atom-ph); Quantum Physics (quant-ph)
We present a universal framework to harness fermionic ultracold atom platforms for quantum simulation, showing how variational algorithms on existing hardware can simulate many-body systems well beyond the hardware's native Hamiltonian. Our analysis provides evidence that one can quantum simulate the ground-state properties of a broad class of gapless target Hamiltonians of local observables in a quantum evolution time that grows polynomially with the inverse relative error, $T\sim O(\mathrm{poly}(1/\epsilon))$ up to logarithmic corrections, offering an exponential speedup over na{ï}ve classical algorithms such as exact diagonalization. We provide numerical evidence and theoretical argument that this holds for energy density, density-density, and spin-spin correlations in three qualitatively distinct models -- the repulsive Hubbard model; a Hubbard model augmented with nearest-neighbor attractive interactions, which introduces the phenomenon of pairing; and the Hofstadter-Hubbard model, which introduces a gauge field and fractional quantum Hall physics. This work demonstrates quantum simulation using current fermionic platforms far beyond the models natively implemented in the hardware.