Computational Physics · Cross-listed from cond-mat.mtrl-sci
Shining light on short-range atomic ordering in semiconductors alloys
Anis Attiaoui, Shunda Chen, Joseph C. Woicik et al. (+7 more)
The functional properties of
semiconductors are typically controlled by tailoring their chemical composition and their state of strain, and by controlling their long-range structural order, including the presence of extended defects such as dislocations. In addition to these approaches, theoretical predictions suggest that short-range order (SRO) of atoms in group-IV
semiconductor alloys can modify the bandgap, a defining property of any
semiconductor. Herein, a new machine learning enabled, computation-guided methodology for extended X-ray absorption fine structure (EXAFS) analysis of SRO is used to quantify the effects of local atomic order on the bandgap of germanium-tin (GeSn)
alloy single
crystal nanostructures with well-controlled strain and composition. Correlative analysis of EXAFS and photoluminescence (PL) establishes the relationship between bandgap and the Warren-Cowley short-range order (WC-SRO) parameter of the GeSn
alloys. It is further demonstrated that SRO can be tuned over a broad range by post-deposition annealing of the
alloy crystals. This work establishes control of SRO as an important design parameter for semiconducting properties and suggests the potential for quantitative measurement and tuning of SRO in other
semiconductor alloy systems.
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All authors Anis Attiaoui, Shunda Chen, Joseph C. Woicik, J. Zach Lentz, Liliane M. Vogl, Jarod E. Meyer, Kunal Mukherjee, Andrew Minor, Tianshu Li, Paul C. McIntyre
Chemical Physics
Enhancing Spin Coherence of Optically-Addressed Molecular Qubit by Nuclear Spin Hyperpolarization
Boning Li, Patrick Hautle, Duhan Zhang et al. (+6 more)
Optically addressable molecular triplet
spins provide a chemically tunable platform for
quantum application, but their coherence is often limited by interactions with surrounding
spin baths. Here we demonstrate controlled suppression of
nuclear-bath-induced decoherence in photoexcited triplet
spins of pentacene co-crystallized in high-purity naphthalene single
crystals. By hyperpolarizing the
proton spin bath through triplet dynamic
nuclear polarization (triplet-DNP),
magnetic noise generated by the
nuclear spins is suppressed, leading to an extension of the electron
spin transverse coherence time. Experimentally, we observe a 25% enhancement of the
spin-echo decay time with $60\%$ polarization of the
proton spin bath. The measured scaling of the
spin-echo decay time ($T_2$) with
nuclear polarization quantitatively follows the predicted dependence derived from the polarization-controlled
nuclear second moment. Both the enhancement and the absolute value of the coherence time are quantitatively reproduced by cluster correlation expansion (CCE) simulations. These results establish
nuclear spin hyperpolarization as a general and actively tunable approach to engineering coherence in molecular
qubits. This work provides a broadly applicable design framework for high-coherence molecular and solid-state
spin systems.
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All authors Boning Li, Patrick Hautle, Duhan Zhang, Liangping Zhu, Ashley Beers, Zeyu Wang, Paola Cappellaro, Tom Wenckebach, Yifan Quan
Geophysics
Relative Focal Mechanism Inversion Using Relative Polarities and S/P Double Ratios
Miao Zhang
Focal mechanisms of small earthquakes are critical for characterizing faults and regional stress. P-wave polarities and S/P amplitude ratios (e.g., in HASH) are widely used to determine focal mechanisms for small earthquakes, but first-motion picking can be difficult for emergent onsets, and S/P ratios are often highly inconsistent because of imperfect velocity models and unknown site responses. Here, I present FocMecDR, a relative focal-mechanism inversion method that uses relative polarities and double ratios of S/P amplitudes. Analogous to double-difference earthquake location, FocMecDR uses a reference event with a known focal mechanism to solve focal mechanisms for nearby earthquakes by minimizing the misfit between observed and theoretical S/P amplitude double ratios while enforcing cross-correlation-based relative polarities. Extensive synthetic tests demonstrate the effectiveness and accuracy of the method. Field verification using an antisimilar earthquake pair and aftershocks from the northwestern end of the 2019 Ridgecrest rupture zone further confirms its reliability. Application to the foreshocks preceding the 2019 Ridgecrest mainshock reveals a highly uniform stress field during nucleation, suggesting a possible framework for evaluating fault-zone stress and rupture readiness before large earthquakes.
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Physics and Society
Affective Polarization on Small-World and Scale-Free Networks
Alisson Serracín Morales and Buddhika Nettasinghe
Affective polarization, the emotional divide characterized by in-group love (trust towards fellow partisans) and out-group hate (mistrust towards those with opposite political views), has become prevalent in the current society. Despite its prevalence, the role of social network structure in the dynamics of affective polarization is yet to be well-understood. We provide a mean-field approximation of opinion dynamics under affective polarization on Watts-Strogatz and power-law (scale-free) networks. Our results show that consensus is fragile in social networks with power-law degree distributions, and the smaller average path length of the network (resembling a small-world network) makes achieving the consensus further difficult. Simulations and numerical experiments on real-world networks indicate that the mean-field model is aligned with the actual dynamics. Our findings shed light on how real-world network properties shape the dynamics of affective polarization and why consensus remains elusive in the real-world.
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Fluid Dynamics
Efficacy of the Weak Formulation of Sparse Nonlinear Identification in Predicting Vortex-Induced Vibrations
Haimi Jha, Hibah Saddal and Chandan Bose
Vortex-induced vibrations (VIV) remain a canonical yet complex manifestation of fluid-structure interactions, where coupled nonlinear dynamics govern the motion of bluff bodies. For several years, we have relied on traditional reduced-order mathematical models derived from empirical and oscillator-based formulations; however, such models often fail to reproduce the quantitative dynamics observed in realistic flow environments. In this study, we explore a data-driven framework that leverages sparse identification of nonlinear dynamics (SINDy) and its weak formulation to uncover the governing equations of a single-degree-of-freedom cylinder undergoing VIV, using both data generated from previously developed reduced-order models and high-fidelity simulation results to assess the interpretation and efficacy of models discovered from a purely data-driven approach, particularly when the underlying dynamics are not fully known. The weak formulation (WSINDy), which replaces numerical differentiation with an integral-based representation, demonstrates marked robustness for aperiodic dynamics in particular. A complementary analysis using proper orthogonal decomposition (POD) is employed to extract the dominant spatio-temporal structures of the flow and to assess whether the temporal
evolution of the wake can be represented on a reduced-dimensional
manifold. The findings establish that data-driven identification can recover interpretable, quantitatively reliable models of VIV, providing a robust and computationally efficient pathway for modelling fluid-structure interactions directly from data. In particular, WSINDy is shown to be a more robust and interpretable alternative to standard SINDy for discovering VIV equations from aperiodic response dynamics, paving the way for predictive, data-informed design of fluid-structure interaction systems.
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Plasma Physics
From molecular dynamics to kinetic models: data-driven generalized collision operators in 1D3V plasmas
Yue Zhao, Guosheng Fu and Huan Lei
We present a data-driven approach for constructing generalized collisional kinetic models for inhomogeneous
plasmas in one-dimensional physical space and three-dimensional velocity space (1D-3V). The collision operator is directly learned from micro-scale molecular dynamics (MD) and accurately accounts for the unresolved particle interactions over a broad range of
plasma conditions. Unlike the standard Landau operator, the present operator takes an anisotropic, non-stationary form that captures the heterogeneous collisional energy transfer arising from the many-body interactions, which is crucial for
plasma kinetics beyond the weakly coupled regime. Efficient numerical evaluation is achieved through a low-rank tensor representation with $O(N \log N)$ computational complexity. The constructed kinetic equation strictly preserves conservation laws and physical constraints and therefore, enables us to develop an explicit second-order, energy-conserving scheme that ensures fully discrete conservation of mass and total energy. Numerical results demonstrate that the present model accurately predicts both transport coefficients and several 1D-3V kinetic processes compared with MD simulations across a broad range of densities and temperatures in spatially inhomogeneous settings. This work provides a systematic pathway for bridging micro-scale MD and inhomogeneous
plasma kinetic descriptions where empirical models show limitation.
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Optics
Enhanced dynamic range spatio-spectral metrology of few-cycle laser pulses
Cristian Alexe, Aaron Liberman, Saga Westerberg et al. (+13 more)
Accurate spatio-temporal and spatio-spectral metrology is critical to the characterization and use of ultra-short, high-power
lasers. The emergence of few cycle pulses, with bandwidths of tens or hundreds of nanometers, poses a significant challenge to existing metrology techniques. This is due both to large discrepancies in the sensitivities of the measurements at different wavelengths and to variation in the spectral intensity at those wavelengths. In this paper, the authors propose spectral filtering and stitching of the measurements as a robust, simple solution that enhances the dynamic range of the measurements, allowing accurate few-cycle pulse reconstruction. This enhancement is demonstrated using INSIGHT – the most commonly used spatio-spectral measurement device – as well as using IMPALA and spatially resolved
Fourier transform spectrometry.
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All authors Cristian Alexe, Aaron Liberman, Saga Westerberg, Andrea Angella, Anda-Maria Talposi, Erik Löfquist, Alice Dumitru, Andrew H. Okukura, Flanish D'Souza, Cornelia Gustafsson, Anders Persson, Chen Guo, Cord Arnold, Olle Lundh, Victor Malka, Daniel Ursescu
Physics and Society
Parliamentary Efficiency under Majority and Supermajority Rules: The Role of Independent Legislators
Gerardo Millar-Sáez, Ignacio Ormazábal and Hernán F. Astudillo
Parliaments dominated by two political blocs often face legislative inefficiencies as polarization increases. A central institutional question concerns how majority and supermajority rules interact with parliamentary composition to balance governability and minority protection. This article examines how the inclusion of independent legislators, introduced through sortition, affects collective decision-making under different majority and supermajority quorum requirements. Using an
agent-based model that combines analytical threshold derivations with numerical simulations, we identify four critical thresholds that partition the parameter space into distinct coalition regimes. These regimes range from majority-party dominance to minority veto and, at high levels of diversity, to structural fragmentation in which coordination becomes increasingly difficult. Parliamentary efficiency emerges from non-linear interactions among quorum thresholds, party-size distribution, and the proportion of independents. Under simple majority, the system exhibits an interior efficiency maximum associated with a transition from unilateral control to pivot-based coalition formation. Under strong supermajorities, however, the same increase in diversity may induce minority veto dynamics or coordination breakdown, significantly reducing legislative performance. These results show that institutional performance is not an intrinsic property of a particular decision rule but an emergent outcome of the interaction between approval thresholds, parliamentary composition, and the coalition structures they generate.
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Fluid Dynamics · Cross-listed from math.AP
Weakly nonlinear models for hydroelastic water waves
Diego Alonso-Orán, Rafael Granero-Belinchón and Juliana S. Ziebell
In this work, we derive reduced interface models for hydroelastic water waves coupled to a nonlinear viscoelastic plate. In a weakly nonlinear small-steepness regime we obtain bidirectional nonlocal
evolution equations capturing the interface dynamics up to quadratic order, and we also derive two unidirectional models describing one-way propagation while retaining the leading dispersive and dissipative effects induced by the plate. Remarkably, one of the bidirectional model has a doubly nonlinear structure in the sense that there there is a nonlinear
elliptic operator acting on the acceleration of the interface. We prove local well-posedness for the bidirectional model for small data via a two-parameter regularization and nested fixed points. For the unidirectional models, we obtain local well-posedness for arbitrary data and global well-posedness for small data.
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Fluid Dynamics
Effects of Plunging Acceleration on the Passive Morphing of Avian-Inspired Flexible Foils
Hibah Saddal, Lucky Babu Jayswal and Chandan Bose
This study investigates the dynamics of passively morphing foils under accelerated plunging, establishing mechanistic links between transient kinematics, structural compliance, and aerodynamic performance. Two-way coupled simulations are performed for three wing geometries: a symmetric NACA0012 foil and two bio-inspired geometries based on falcon and owl wing sections, across non-dimensional bending
rigidity values, chordwise flexible segment extents from the trailing-edge (25%, 50%, and 75%), and transition speed parameters. The present findings reveal that flexible trailing-edge configurations exhibit improved aerodynamic performance relative to stiffer foils, and the aerodynamic benefit of trailing-edge compliance is strongly influenced by wing geometry. A geometry-specific optimal bending stiffness exists beyond which additional flexibility degrades performance. The extent of the chordwise flexible segment critically governs the aeroelastic response. Whilst a 25% flexible segment produces behaviour indistinguishable from a rigid wing, extending flexibility to 75% of the chord induces highly unsteady lift fluctuations, particularly for the NACA0012 foil, for which the root-mean-square lift coefficient increases sharply. The bio-inspired foils, in contrast, exhibit a moderate reduction in root-mean-square lift coefficient for the 50% and 75% cases, reflecting the stabilising influence of their cambered geometry. Increasing the transition speed parameter monotonically amplifies trailing-edge deflection, strengthens the leading- and trailing-edge
vortices, and intensifies the coupling between structural deformation and instantaneous lift. These findings provide new physical insight into bio-inspired propulsion and manoeuvring strategies, with implications for the design of passively adaptive lifting surfaces in unsteady environments.
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Physics and Society · Cross-listed from cs.CY
Views on AI Existential Risk Before and After a Public Event at Harvard University
Greg Kestin and Nate Soares
We report the results of identical pre- and post-event surveys given to attendees of a talk, two-sided conversation, and Q&A centered around the book If Anyone Builds It, Everyone Dies at Harvard University in March 2026, covering perceived probability of AI-caused extinction or severe disempowerment resulting from unimpeded AI development, confidence in those estimates, and global priority. Among the 89 matched participants, the post-event median estimate of the probability of existential risk from advanced AI was 70%, and 96% agreed that mitigating AI existential risk should be a global priority. Although these self-selected respondents' pre-event views were already high (50% and 93%, respectively) relative to results of similar surveys that were previously administered to experts and the general public, the event produced increases on all measures when considering the respondents in aggregate. The magnitudes of increases in risk probability were negatively correlated with prior familiarity with the topic: among attendees with little prior familiarity, 60% shifted upward and none shifted downward, whereas among self-described experts, no respondents shifted upward and 20% shifted downward. Self-reported confidence also increased significantly, and confidence shifts were positively correlated with probability shifts. These findings indicate that a structured public engagement event can meaningfully shift risk perceptions, particularly among newcomers to the topic.
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Chemical Physics
Understanding the Density Maximum of Water with Machine Learned Potentials
Yizhi Song, Renxi Liu, Chunyi Zhang et al. (+5 more)
After melting, at ambient pressure, the density of water continues to increase with temperature until it reaches a maximum around 4 {\deg}C. For nearly a century, this phenomenon has been qualitatively attributed to a mixture of ordered and disordered structures. Herein, we employ a deep neural network to train a machine learned (ML) interatomic potential for water using electronic structure data from advanced density functional theory. Notably, molecular dynamics simulations with the ML potential reproduce both the experimental water density anomaly and the thermal expansion coefficient. Detailed structural analysis of the computed hydrogen-bond network reveals that the density anomaly arises from an emergent
liquid structure that retains nearly ideal tetrahedral coordination at short range but collapses at intermediate range. Our findings point to a more delicate mechanism causing the density maximum than the conventional picture, emphasizing the collective roles of structural orderings at different length scales.
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All authors Yizhi Song, Renxi Liu, Chunyi Zhang, Yifan Li, Biswajit Santra, Mohan Chen, Michael L. Klein, Xifan Wu
Computational Physics
Exact Phase-Space Analytical Solution for the Power-Law Damped Contact Oscillator
Y. T. Feng
We present an exact phase-space analytical treatment of the power-law damped contact oscillator governed by $m\ddot{\delta} + \alpha\sqrt{mk_H}\,\delta^{(p-1)/2}\dot{\delta} + k_H\delta^p = 0$, valid for all force-law exponents $p \geq 1$ and all initial impact velocities $v_0$. The central result is the transformation $\delta = Ax^{2/(p+1)}$, where $A = [(p+1)/2]^{1/(p+1)}$, which maps the nonlinear phase-space equation $v\,dv/d\delta + \dots = 0$ exactly onto a linear spring-dashpot (LSD) system with effective damping ratio $\alpha_\text{eff} = \frac{\alpha}{\sqrt{2(p+1)}}$. The phase portrait $v(\delta)$, coefficient of restitution $e$, and maximum penetration $\delta_\text{max}$ follow in closed form. The physical time-domain solution $(\delta(t), v(t))$ is obtained parametrically via a single quadrature, which evaluates analytically for $p=1$ and at negligible numerical cost for all other $p$. We prove that $e$ is exactly independent of $v_0$ for all $p \geq 1$ and derive the universal calibration formula: $\alpha = \sqrt{2(p+1)}\cdot\frac{-\ln e}{\sqrt{\pi^2 + \ln^2 e}}$. This generalises the known results for $p=1$ (linear spring-dashpot) and $p=3/2$ (Hertz contact, Antypov and Elliott, 2011) to the entire power-law family. A closed-form estimate for the critical timestep of explicit time integration is also derived, exhibiting universal scaling with impact velocity and force-law exponent.
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Applied Physics · Cross-listed from cond-mat.mes-hall
Benzo-bis(imidazole) self-assembled monolayers molecular junctions in meta or para conformation: effects of protonation on the electrical and thermal conductances
Sergio Gonzalez-Casal, Simon Pascal, Olivier Siri et al. (+1 more)
We report the thermal conductances of molecular junctions made of self-assembled monolayers of benzo-bis(imidazole) molecules, without side groups or functionalized with two phenylamine side groups. In the two cases, when the molecules are connected to the electrodes by thiol anchoring groups in the meta-position, the thermal conductance is decreased compared to the same molecules connected in the para-position (ca. 16-29 nW/K and ca. 37-40 nW/K, respectively) in agreement with the theoretically predicted
phonon interference effect in molecular junctions. Upon protonation, the thermal conductances of the meta-connected molecular junction increase by about 50% (reversible behavior upon deprotonation). The fact that only the thermal conductance of the meta-connected molecular junction is sensitive to the protonation/deprotonation is tentatively related to modifications of the structural organization of the molecules in the monolayer, which modifies the thermal conductance at the molecule/electrode interfaces. The electrical conductance is lower for the meta-connected molecule than for the para-connected one, due to destructive
quantum interferences, as expected and reported for other molecular junctions. The conductance further decreases (reversibly) upon protonation. The energy position of the molecular orbital involved in the electron transport is not modified by the protonation and the decrease in current is related to changes in the molecule organization in the monolayer, which modulate the electronic coupling energy at the molecule/electrode interfaces.
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All authors Sergio Gonzalez-Casal, Simon Pascal, Olivier Siri, Dominique Vuillaume
Geophysics · Cross-listed from cond-mat.soft
Cratering by the oblique impact of a spinning projectile
Douglas Daniel de Carvalho and Erick de Moraes Franklin
We investigate the roles of
spin and packing fraction on the dynamics of cratering when a solid projectile impacts a granular bed at different incident angles. For that, we carried out DEM (discrete element method) computations in which we varied the magnitude and direction of the projectile
spin, the impact velocity, the bed packing fraction, and the incident angle. For a given incident velocity, we found that the projectile can rebound for small angles, or be completely or partially buried for larger angles, and that when buried it can sometimes migrate large horizontal distances depending on the incident angle. We also found that increasing the packing fraction strengthens rebounds, and that the initial
spin, depending on its direction and orientation, induces rebound, burying, or transverse deviations. The crater morphology also changes with the varying parameters, acquiring circular, elliptical, goutte-like, tadpole-like, and transitional shapes, correlating well with the projectile behavior. Finally, we propose diagrams organizing and classifying the dynamics observed. Our results shed new light on the different shapes of craters found in nature and the fate of the impacting material.
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Optics
Tailoring Quasi-Bound States in the Continuum for Infrared Photodetection in Black Phosphorus
Xiao Liu, Tianxiang Zhao, Ting Wang et al. (+6 more)
High-performance infrared photodetection underpins various applications spanning surveillance, environmental monitoring, optical communications and biomedical imaging. However, conventional bulk detectors remain limited by poor spectral tunability, mechanical
rigidity, and high dark currents, motivating the pursuit of low-dimensional material platforms such as
graphene and transition metal dichalgenides. Black phosphorus (BP) is particularly compelling in this context, owing to its thickness-tunable direct bandgap, high carrier mobility, and pronounced in-plane anisotropy. Nevertheless, its atomically thin nature inherently restricts light absorption, posing a fundamental bottleneck for device performance. Here, we demonstrate quasi-bound states in the continuum (quasi-BICs) within a dielectric metasurface integrated with BP, enabling strongly enhanced and spectrally selective light-matter interactions. By introducing controlled
symmetry breaking at the unit-
cell level, high-quality-factor resonances are realized, resulting in pronounced electromagnetic field confinement within the BP layer. This resonant enhancement substantially increases photocarrier generation while preserving the intrinsic polarization anisotropy of BP, which elucidates a robust pathway for overcoming the optical absorption bottleneck in anisotropic 2D optoelectronics via quasi-BIC platforms.
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All authors Xiao Liu, Tianxiang Zhao, Ting Wang, Junsheng Xu, Junyong Wang, Kai Zhang, Hongliang Li, Xuechao Yu, Junjia Wang
Instrumentation and Detectors
Suppression of $^{14}\mathrm{C}$ photon hits in large liquid scintillator detectors via spatiotemporal deep learning
Junle Li, Zhaoxiang Wu, Guanda Gong et al. (+5 more)
Liquid scintillator detectors are widely used in
neutrino experiments due to their low energy threshold and high energy resolution. Despite the tiny abundance of $^{14}$C in LS, the
photons induced by the $\beta$ decay of the $^{14}$C isotope inevitably contaminate the signal, degrading the energy resolution. In this work, we propose three models to tag $^{14}$C
photon hits in e$^+$ events with $^{14}$C pile-up, thereby suppressing its impact on the energy resolution at the hit level: a gated spatiotemporal graph neural network and two
Transformer-based models with scalar and vector charge encoding. For a simulated test
dataset in which each event contains one $^{14}\mathrm{C}$ and one e$^+$ with kinetic energy below 5 MeV, the models achieve $^{14}\mathrm{C}$ recall rates of 25%-48% while maintaining $\mathrm{e}^{+}$ to $^{14}\mathrm{C}$ misidentification below 1%, leading to a large improvement in the resolution of total charge for events where $\mathrm{e}^{+}$ and $^{14}\mathrm{C}$
photon hits strongly overlap in space and time.
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All authors Junle Li, Zhaoxiang Wu, Guanda Gong, Zhaohan Li, Wuming Luo, Jiahui Wei, Wenxing Fang, Hehe Fan
Computational Physics
A finite-precision Lanczos-Golub-Welsch route to probability-table construction in resonance self-shielding
Beichen Zheng
This work reformulates Chiba's affine-order prescription as a
polynomial-moment problem for a transformed positive measure, and develops an alternative finite-precision construction route based on this reformulation. The proposed construction proceeds through discrete-measure realization, symmetric Lanczos reduction, and Golub–Welsch extraction, replacing the conventional moment–Pade pipeline. The subgroup total levels and probabilities are obtained by a Gauss-type compression step that preserves nonnegative-realness, while the reaction-channel levels are recovered on the compressed nodes by orthogonal-basis matching. In five tested resonance-channel cases, the proposed construction yields lower effective-cross-section errors and avoids the order-induced emergence of complex responses observed in the conventional construction.
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Applied Physics
Low-loss phononic integrated circuits based on a silicon nitride-lithium niobate platform
Jun Ji, Joseph G Thomas, Zichen Xi et al. (+7 more)
Microwave-frequency acoustic waves in solids have emerged as a versatile platform for both classical and
quantum applications. While phononic integrated devices and
circuits are being developed on various material platforms, an ideal phononic integrated
circuit (PnIC) platform should simultaneously support low-loss waveguide structures, high-quality-factor resonators, high-performance modulators, and efficient electromechanical transducers. Here, we establish a low-loss gigahertz-frequency PnIC platform based on patterned thin-film silicon nitride (SiN) on lithium niobate (LN) substrate. We develop low-loss PnIC building blocks including waveguides, directional couplers, and high-quality-factor (high-Q) ring resonators. As an application, we demonstrate a 1-GHz phononic oscillator based on a ring resonator, reaching a low phase noise of -159.0 dBc/Hz at a 100-kHz offset frequency. Our low-loss PnICs could meet the requirements in microwave acoustics,
quantum phononics, and integrated hybrid systems combining
phonons,
photons, superconducting
qubits, and solid-state defects.
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All authors Jun Ji, Joseph G Thomas, Zichen Xi, Ruxuan Liu, Kinson Fang, Yuan Qin, Andreas Beling, Xu Yi, Yizheng Zhu, Linbo Shao
Optics · Cross-listed from quant-ph
Birefringent Curvature Control of Surface Plasmons and Collective Emission
Florian Bönsel and Flore K. Kunst
We present a generic wave equation for surface plasmon polaritons on any macroscopically curved metal-dielectric interface, with isotropic and anisotropic
geometric potentials linear in
curvature. Remarkably, the anisotropic birefringence vanishes if the metal-to-dielectric permittivity ratio equals the golden ratio squared, mimicking isotropy at linear order on an actually anisotropic surface, as confirmed by full-wave simulations. Applying our equation to
quantum emitters on metallic spheres, we demonstrate a
curvature-controlled reshaping of collective decay rates and frequency shifts.
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Atmospheric and Oceanic Physics
Calibrated Conformal Prediction Intervals for Microphysical Process Rates
Miriam Simm, Corinna Hoose and Tom Beucler
Conformal prediction can yield statistically valid prediction intervals for any regression model, with no model modifications and small computational costs. To assess its practical value, we apply conformal methods to quantify uncertainty in machine learning emulators of six microphysical process rates. Microphysical process rates describe small-scale processes in atmospheric clouds such as precipitation formation and aerosol-cloud interactions, and help understand weather and
climate. The emulators are trained on simulation output from the ICOsahedral Nonhydrostatic (ICON) model in a limited-area numerical weather prediction configuration. We compare split conformal prediction for deterministic emulators with conformalized
quantile regression for
quantile regression emulators. Both conformal prediction methods yield well-calibrated and sharp prediction intervals on average, but conformalized
quantile regression provides more consistent intervals across several orders of magnitude, making it preferable for the uncertainty quantification of
climate variables.
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Accelerator Physics
Strong-field focusing of high-energy particles in beam-multifoil collisions
Aimé Matheron, Doug Storey, Max F. Gilljohann et al. (+25 more)
Extreme beams of charged particles and
photons, reaching ultrahigh densities or producing intense gamma-ray bursts, are central to accelerator physics, laboratory astrophysics, and strong-field
quantum electrodynamics research. Yet their generation is hindered by conventional focusing methods at multi-GeV energies that rely on massive
magnetic assemblies, limiting compactness and attainable density. Here we report the first experimental observation of a fundamentally new focusing mechanism, in which a high-energy charged-particle beam is focused by its own
magnetic field reflected from a stack of thin metallic foils via near-field coherent-transition-radiation. The experiment, performed at SLAC's FACET-II facility, reveals strong, cumulative focusing across a broad range of beam configurations, enabled by the delivered 10 GeV, 1 nC, 10 Hz electron beam. The measurements closely agree with predictions from an analytical model and particle-in-
cell simulations. These results demonstrate that multifoil focusing is a remarkably straightforward, self-aligned approach to the generation of ultrahigh density beams, opening a path to explore unprecedented regimes of beam-matter interaction and high-energy radiation.
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All authors Aimé Matheron, Doug Storey, Max F. Gilljohann, Sheldon Rego, Erik Adli, Igor A. Andriyash, Gevy J. Cao, Xavier Davoine, Claudio Emma, Frederico Fiuza, Spencer Gessner, Laurent Gremillet, Claire Hansel, Chan Joshi, Christoph H. Keitel, Alexander Knetsch, Valentina Lee, Michael D. Litos, Nathan Majernik, Yuliia Mankovska, Brendan O'Shea, Ivan Rajkovic, Pablo San Miguel Claveria, Viktoriia Zakharova, Chaojie Zhang, Mark J. Hogan, Matteo Tamburini, Sébastien Corde
Computational Physics · Cross-listed from cond-mat.mtrl-sci
Solving the inverse problem of X-ray absorption spectroscopy via physics-informed deep learning
Suyang Zhong, Boying Huang, Pengwei Xu et al. (+6 more)
Resolving transient atomic configurations in non-crystalline or dynamic environments remains a fundamental bottleneck in the physical sciences. While X-ray absorption spectroscopy (XAS) is a premier probe of local structure, inverting spectra into structural descriptors is a notoriously ill-posed problem due to inherent many-to-one mapping. Here, we present the Spectral Pattern Translator (SPT), a physics-informed deep learning framework that establishes a robust bridge between large-scale theoretical
datasets and experimental reality. Our strategy exploits the
Fourier duality between spectral energy oscillations and spatial scattering paths to overcome the "simulation-to-experiment" gap. By decomposing spectra into frequency domains, SPT effectively isolates robust structural coordination signals from the destabilizing noise inherent in experimental data. Trained on a massive library of diverse atomic environments, this approach achieves state-of-the-art accuracy in resolving continuous phase transitions in battery cathodes and deciphering local order in amorphous materials. With millisecond-scale latency, SPT removes the primary computational barrier to autonomous materials discovery, establishing a robust, noise-resilient engine for closed-loop robotic chemistry.
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All authors Suyang Zhong, Boying Huang, Pengwei Xu, Fanjie Xu, Yuhao Zhao, Jun Cheng, Fujie Tang, Weinan E, Zhong-Qun Tian
Fluid Dynamics
Modeling of Reaction Dynamics in a Turbulent Hydrogen-Air Slot Flame Using Resolvent Analysis
Anant Talasikar, Marina Matthaiou, Michael Gauding et al. (+2 more)
This work applies Resolvent Analysis (RA) to study the dynamics of a hydrogen-air slot flame with a Reynolds number of 5500, a Karlovitz number of 20, and an equivalence ratio of 0.4. Direct Numerical Simulations (DNS) data are analyzed using shifted Spectral Proper Orthogonal Decomposition (SPOD), and the resulting structures are compared with optimal resolvent responses obtained from the linearization of a RANS-EBU reaction rate model. Both SPOD and RA show that the flow dynamics are dominated by Kelvin-Helmholtz wave packets over a broad frequency range, particularly between 300 and 1000 Hz. This behavior is reflected in the resolvent gains and SPOD
eigenvalues, which exhibit consistent amplification within this range. The velocity fluctuation mode shapes predicted by RA agree well with the SPOD modes. However, the corresponding mode shapes for the progress variable and heat release show weaker agreement. To address this limitation, the study introduces a generalized active-flame closure calibrated with high-fidelity data, which remains compatible with the linearized framework and improves the agreement with SPOD modes. Overall, the results indicate that thermodiffusive instabilities in turbulent hydrogen flames do not hinder the applicability of the active-flame resolvent approach.
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All authors Anant Talasikar, Marina Matthaiou, Michael Gauding, Heinz Pitsch, Thomas Ludwig Kaiser
Popular Physics
The Structure of Scientific Socialism: Quantum Emergence, Frustration, and the Non-Dual Dialectic
Sindhunil Barman Roy
Classical Marxism and the
algebra of revolution were formulated within the ontological constraints of 19th-century Newtonian materialism-a world of discrete, predictable, billiard-ball interactions. However, the 20th-century transitions in physics, from Thomas Kuhn's paradigm shifts to Phil Anderson's philosophy of emergence, have dismantled the reductionist foundations of this mechanical worldview. This paper proposes a New Manifesto for Scientific Socialism by synthesizing modern condensed matter physics with the non-dual philosophy of Advaita Vedanta. By examining the concepts of
Geometric Frustration and Competing Interactions through the lens of
Spin-Glasses and Mott
Insulators, we argue that social stasis and synthesis are emergent properties of a universal consciousness field rather than mechanical inevitabilities. We further explore how this
quantum-informed dialectic resolves the essential tension between the individual and the collective, echoing the intuitions of Schrodinger and Heisenberg regarding the foundational unity of reality.
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Computational Physics · Cross-listed from cs.CL
PRBench: End-to-end Paper Reproduction in Physics Research
Shi Qiu, Junyi Deng, Yiwei Deng et al. (+48 more)
AI
agents powered by large
language models exhibit strong
reasoning and problem-solving capabilities, enabling them to assist scientific research tasks such as formula derivation and code generation. However, whether these
agents can reliably perform end-to-end reproduction from real scientific papers remains an open question. We introduce PRBench, a
benchmark of 30 expert-curated tasks spanning 11 subfields of physics. Each task requires an
agent to comprehend the methodology of a published paper, implement the corresponding
algorithms from scratch, and produce quantitative results matching the original publication.
Agents are provided only with the task instruction and paper content, and operate in a sandboxed execution environment. All tasks are contributed by domain experts from over 20 research groups at the School of Physics, Peking University, each grounded in a real published paper and validated through end-to-end reproduction with verified ground-truth results and detailed scoring rubrics. Using an agentified assessment pipeline, we evaluate a set of coding
agents on PRBench and analyze their capabilities across key dimensions of scientific
reasoning and execution. The best-performing
agent, OpenAI Codex powered by GPT-5.3-Codex, achieves a mean overall score of 34%. All
agents exhibit a zero end-to-end callback success rate, with particularly poor performance in data accuracy and code correctness. We further identify systematic failure modes, including errors in formula implementation, inability to debug numerical simulations, and fabrication of output data. Overall, PRBench provides a rigorous
benchmark for evaluating progress toward autonomous scientific research.
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All authors Shi Qiu, Junyi Deng, Yiwei Deng, Haoran Dong, Jieyu Fu, Mao Li, Zeyu Li, Zhaolong Zhang, Huiwen Zheng, Leidong Bao, Anqi Lv, Zihan Mo, Yadi Niu, Yiyang Peng, Yu Tian, Yili Wang, Ziyu Wang, Zi-Yu Wang, Jiashen Wei, Liuheng Wu, Aoran Xue, Leyi Yang, Guanglu Yuan, Xiarui Zhan, Jingjun Zhang, Zifan Zheng, Pengfei Liu, Linrui Zhen, Kaiyang Li, Qichang Li, Ziheng Zhou, Guo-En Nian, Yunwei Xiao, Qing-Hong Cao, Linjie Dai, Xu Feng, Peng Gao, Ying Gu, Chang Liu, Jia Liu, Ming-xing Luo, Yan-Qing Ma, Liang-You Peng, Huichao Song, Shufeng Wang, Chenxu Wang, Tao Wang, Yi-Nan Wang, Chengyin Wu, Pengwei Zhao, Hua Xing Zhu
Optics · Cross-listed from quant-ph
Quantum control and signal enhancement exploiting the Stokes-anti-Stokes coherence
Wen-Zhao Zhang, Keye Zhang and Jie Li
We present a theoretical framework for the coherent coupling between Stokes and anti-Stokes scattering processes, revealing interference phenomena inaccessible to either process alone. Within a dispersive-interaction model beyond the resolved-sideband limit, we show that classical driving and system linewidth coherently links the two channels, enabling phase-controlled interference. Destructive interference induces intrinsic asymmetry in dispersively coupled systems, enabling coherent control of
quantum information storage and transfer, while constructive interference leads to exponential signal amplification and thus enhanced
quantum detection. This work establishes a unified picture for understanding Stokes-anti-Stokes coherence as a fundamental mechanism underlying both
quantum control and metrology. Furthermore, it suggests that these functionalities can be further enhanced by implementing Stokes-anti-Stokes arrays.
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Space Physics · Cross-listed from astro-ph.EP
Closeby Habitable Exoplanet Survey (CHES). V. Planetary Parameters Derived from Angular Separation Variations
Dongjie Tan, Jianghui Ji, Chunhui Bao et al. (+11 more)
The Closeby Habitable
Exoplanet Survey (CHES) aims to achieve microarcsecond-level astrometry of about one hundred nearby FGK-type
stars within 10 parsecs to detect Earth-like
planets. Such precision exceeds the capability of absolute astrometry relying on
Gaia catalogs, whose positional accuracy degrades over time due to error propagation from
stellar motion and epoch offsets, limiting their use in microarcsecond-level detection. Traditional relative astrometry depends on positional components along right ascension and declination, requiring precise knowledge of field rotation and satellite attitude, which introduces additional errors. To address this, we propose a new relative measurement model based solely on variations in the length of angular separation between the target and reference
stars, independent of direction. The model incorporates effects such as proper motion, parallax, radial velocity, light aberration, gravitational
lensing, and planetary perturbations, enabling reconstruction of planetary orbits and masses. This approach enhances measurement stability and precision, providing a framework that is not entirely dependent on the
Gaia catalog and suitable for CHES and other future high-accuracy astrometric missions.
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All authors Dongjie Tan, Jianghui Ji, Chunhui Bao, Xiumin Huang, Guo Chen, Su Wang, Yao Dong, Jiacheng Liu, Zi Zhu, Haitao Li, Junbo Zhang, Liang Fang, Dong Li, Lei Deng
Optics
Single-Step Grayscale Lithography of Multi-Depth Mie Void Metasurfaces
Oren Goldberg, Noa Mazurski and Uriel Levy
The height of dielectric metasurfaces is largely considered a constant in the fabrication process due to the top-down fabrication approach, resulting in a binary structure. Yet, for the recently introduced Mie voids metasurfaces, controlling the thickness of the voids locally is crucial for achieving significant spectral tuning. In this work we demonstrate Mie voids metasurfaces with local precise depth control using electron beam grayscale lithography. We underexpose PMMA with varying doses, which in turn translates to multiple depth levels in the developed resist. Transferring the pattern to a silicon substrate we generate Mie voids, trapping the light in the void which generates colors in reflection. By controlling the depth of the void at the nanoscale, we tune the resonance over the whole visible range and with high precision, resulting in a large gamut of colors, which is demonstrated with spectral measurements, images of uniform patterns and spatially varying patterns showcasing different geometrical designs and a detailed artistic image. The demonstrated approach can be used for the implementation of various types of dielectric metasurfaces, providing an additional important degree of freedom for their realization, with potential applications in structured light and structural colors, imaging, robotics, polarization control, sensing, virtual reality and more.
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Instrumentation and Detectors
Precision timing detectors
Martina Malberti and Xiaohu Sun
Precision timing has played a critical role in high-energy physics experiments, particularly for particle identification and the suppression of pileup under the challenging conditions expected at future
colliders like the High-Luminosity Large
Hadron Collider (HL-LHC). Over the past decades, significant advancements in timing measurement technologies have been made to meet the demands of increasingly complex
collider environments. After introducing the motivation for precision timing in
collider experiments, the underlying physical principles of timing measurements and the most important factors influencing the time resolution of a detector, this review presents a survey of key detector technologies developed in recent years, including scintillators read out by silicon photo-multipliers (SiPMs), low-gain avalanche diodes (LGADs), multi-gap resistive plate chambers (MRPCs). The integration of precision timing into large-scale systems is discussed with examples from detectors at current
collider experiments. Finally, we explore emerging technologies and future directions in the field, highlighting their potential impact on the next generation of high-energy physics experiments.
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