Biological Physics
Biology and Physics
Stuart A. Newman and Sahotra Sarkar
This article frames the relation between biology and physics by characterizing the former as a subdiscipline rather than a special case of the latter. To do this, we posit biological physics as the science of living matter in contrast to classic biophysics, the study of organismal properties by physical techniques. At the scale of the individual
cell, living matter is nonunitary, i.e., not composed of aggregated subunits, and has features (e.g., intracellular organizational arrangements and biomolecular condensates) that are unlike any materials of the nonliving world. In transiently or constitutively multicellular forms (social microorganisms, animals, plants), living matter sustains physical processes that are generic (shared with nonliving matter, e.g., subunit communication by molecular
diffusion in cellular slime molds), biogeneric (analogous to nonliving matter but realized through cellular activities, e.g., subunit demixing in animal embryos) or nongeneric (pertaining to sui generis materials, e.g., budding of active solids in plants). This "forms of matter" perspective is philosophically situated in the dialectical materialism of Engels and Hessen and the multilevel physicalism of Neurath and the logical empiricists. We counterpose this view to informationism and to genetic and other hierarchically reductionist physical theories of biological systems and highlight open questions regarding incompletely characterized and enigmatic forms of living matter.
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Plasma Physics
Differentiable Programming for Plasma Physics: From Diagnostics to Discovery and Design
A. S. Joglekar, A. G. R. Thomas, A. L. Milder et al. (+3 more)
Differentiable programming, enabled by automatic differentiation (AD), provides a robust framework for gradient-based optimization in computational
plasma physics. While optimization is often only used towards design, we demonstrate that it can also be used for discovery and bridging the gap towards multi-scale modeling. We discuss four applications: (1) discovering novel nonlinear
plasma phenomena, including a previously unknown superadditive wavepacket interaction regime, by optimizing differentiable kinetic simulations; (2) learning hidden variables that capture spatiotemporally non-local kinetic effects in fluid simulations, enabling hydrodynamic models to reproduce large Knudsen number physics typically requiring kinetic solvers; (3) accelerating Thomson scattering analysis by over $140\times$ while enabling extraction of velocity distribution functions with $\mathcal{O}(10^3)$ parameters; and (4) inverse design of spatiotemporal
laser pulses that achieve target far-field behavior where full space-time coupling improves performance by $15\times$ over spatial or temporal optimization alone. These examples illustrate that differentiable programming not only accelerates existing design and inference workflows but enables qualitatively new capabilities, from algorithmic physics discovery to high-dimensional inference and design previously considered intractable.
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All authors A. S. Joglekar, A. G. R. Thomas, A. L. Milder, K. G. Miller, J. P. Palastro, D. H. Froula
Plasma Physics
On the evolution of a large-amplitude, weakly-collisional electron plasma wave
A. S. Joglekar and A. G. R. Thomas
Vlasov-Poisson-Fokker-Planck (VPFP) simulations of large-amplitude electron
plasma waves, where the bounce frequency is much larger than the collision frequency, $\omega_B \gg \nu_\text{ee}$, show that the
evolution of these waves exhibits three phases; I. A short-lived trapping phase during which collisional effects are minimal. II. A long-lived detrapping phase during which collisional effects are most influential. III. A short-lived Landau damping phase where the effect of collisions becomes minimal again. While the dispersion relation during the trapping and Landau damping phase is well known, the wave behavior during the detrapping phase is not as well understood. The simulations show that during the detrapping phase, the interplay between weak electron-electron collisions and strong wave-electron interactions results in an increasing frequency shift further from the linear root, $\omega_\text{EPW}$. At the conclusion of the detrapping phase, the distribution function is nearly Maxwellian, the frequency shift rapidly diminishes, and the wave damps at a larger rate than the Landau damping rate. Empirical fits to the damping rates, frequency shift enhancement rate, and the lifetime of the
plasma waves are provided as functions of collision frequency, wavenumber, and wave amplitude.
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Atomic Physics · Cross-listed from quant-ph
Imaginary time evolution and ground state preparation using unitary multi-copy protocols
Tal Schwartzman, Torsten V. Zache, Hannes Pichler et al. (+1 more)
Efficient low-energy state preparation is a key objective in
quantum computation and
quantum simulation.
Quantum imaginary-time
evolution replaces real-time dynamics with imaginary-time dynamics, exponentially suppressing higher-energy eigenstates. We introduce deterministic
unitary protocols that approximate imaginary-time
evolution for ground state preparation. The protocols require multiple copies of the system, real-time
evolution under the system
Hamiltonian, and controlled-SWAP operations (or more general SWAP-generated
unitaries). Our analysis focuses on two concrete
circuit families: a tree architecture with provable
polynomial-in-depth convergence but rapidly growing width, and a compact "hedge" architecture that achieves comparable accuracy with only
polynomial width in a heuristic construction supported by numerics. Numerical evidence indicates that mid-
circuit post-selection can accelerate convergence with practical success probabilities. Separately, we demonstrate that
circuit volume can be traded for the shot complexity of post-
circuit observable estimation in the ground state preparation setting. Finally, we outline concrete platform-specific implementations in which multi-copy registers and SWAP-mediated couplings are natural, illustrating how these hybrid analog-digital
circuits can complement existing state-preparation methods in the near term.
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All authors Tal Schwartzman, Torsten V. Zache, Hannes Pichler, H. R. Sadeghpour
Biological Physics · Cross-listed from cond-mat.stat-mech
Pattern stability in reaction-diffusion systems depends on path entropy
Eric R. Heller and David T. Limmer
Reaction-
diffusion systems driven far from thermodynamic
equilibrium through the injection of energy can support multiple spatial patterns that persist as long-lived dynamical phases. The stability of these metastable phases is not determined by thermodynamics, but by the transition paths connecting them. At finite particle numbers, intrinsic stochasticity induces rare transitions between competing patterns, rendering continuum mean-field descriptions insufficient, while exact
stochastic simulations become computationally prohibitive in spatially extended systems. Here, we make absolute instanton rate calculations, including fluctuation and
symmetry prefactors, tractable for transitions between metastable patterns in large nonequilibrium reaction-
diffusion systems. Applied to a canonical Schlögl model and an experimentally motivated ATP-driven membrane kinase-phosphatase network, the resulting rates agree closely with reaction-
diffusion master-equation
benchmarks. We show that an effective path
entropy can qualitatively alter stability at finite particle numbers by selectively enhancing one switching direction. These results establish path
entropy as an organizing principle for finite-particle nonequilibrium pattern stability.
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Atomic Physics · Cross-listed from quant-ph
Exact quantum scars from kinetic frustration for cross-platform realizations
Zhuoli Ding, Ruben Verresen and Zoe Z. Yan
Quantum many-body scars are nonthermal states exhibiting persistent revivals in an otherwise ergodic, nonintegrable
quantum system. Here we leverage the phenomenon of kinetic frustration – the destructive interference of multiple
quantum paths – to create exact scars. The simplicity makes these models directly suitable for implementation on multiple existing
quantum simulation platforms. In particular, we show how frustrated hardcore
bosons in cold atom Bose-Hubbard simulators and polar molecule or Rydberg atom tweezer arrays have persistent oscillations whose lifetimes can be tuned with experimentally accessible parameters, like the Hubbard interaction or a Floquet drive. Second, we propose an experimentally realizable scar within a non-integrable
Fermi-Hubbard model where the frustration arises from the fermionic exchange statistics, which admits a one-to-one mapping with the bosonic model in the scar subspace. Finally, we introduce a practical heuristic based on the energy distribution of eigenstates for systematically predicting and optimizing
quantum many-body scar lifetimes. Their cross-platform realizability and long lifetimes make them well-suited for benchmarking coherence and exploring nonergodic dynamics in current and near-term
quantum devices.
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Plasma Physics · Cross-listed from hep-ph
Intrinsic Nonlocality of Spin- and Polarization-Resolved Probabilities in Strong-Field Quantum Electrodynamics
Samuele Montefiori, Antonino Di Piazza, Tobias Podszus et al. (+2 more)
Spin and polarization are central to precision tests of fundamental physics and for interpreting radiation from astrophysical sources and ultraintense
laser-matter experiments. Here, focusing on the fundamental process of nonlinear Compton scattering, we demonstrate that a key assumption underlying current strong-field
quantum electrodynamics (SFQED) models, i.e., that emission can be treated as an instantaneous random event sampled from a local differential rate, is inconsistent once emission angles, electron
spin, and/or
photon polarization are resolved. Namely, even in strictly constant and uniform fields, the resulting fully differential distribution is sign-indefinite, yielding negative inferred probabilities. The physical reason is that the
photon emission probability builds up over a finite length of the electron trajectory, the formation region, during which the electron direction changes by roughly the same small angle that defines the radiation cone. Therefore, we put forward a new method where we integrate over this formation region analytically to obtain a physically consistent electron
spin and
photon polarization model. Simulations of a GeV-class electron-
laser collision accessible at current petawatt facilities and of emission in a
pulsar-like
magnetic field are shown to reveal
spin and polarization patterns that differ even qualitatively from state-of-the-art local models. In particular, our new model predicts substantial angle-dependent circular
photon polarization where the well-known collinear-emission approach yields none, and a pronounced helicity bias in the recoiling electrons absent from current predictions. These findings have direct implications for upcoming strong-field QED experiments and for interpreting polarized radiation from extreme astrophysical environments.
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All authors Samuele Montefiori, Antonino Di Piazza, Tobias Podszus, Christoph H. Keitel, Matteo Tamburini
Classical Physics
Nonlinear potential field in contact electrification
Benjamin J. Kulbago and James Chen
The cause of electron transfer in contact electrification is one of the most hotly debated physical problems today. In this study, the electron transfer is hypothesized to be partly driven by the surface dipole induced potential during contact. This phenomena is demonstrated by a combination of atomistic field theory (AFT) and molecular dynamics (MD) simulation. A representative contact system of carbon and silicon dioxide was chosen for its excellent tribo-tunneling power output performance. The results reveal the existence of a nonlinear potential field as well as the existence of a separation dependent potential barrier at the contact interface. Possible scenarios of triboelectric charge transfer are discussed in light of these results. These results are critical to the fundamental understanding of contact electrification.
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Fluid Dynamics · Cross-listed from math.NA
On the energy dissipation rate of ensemble eddy viscosity models of turbulence: Shear flows
William Layton
Classical eddy viscosity models add a viscosity term with turbulent viscosity coefficient developed beginning with the Kolmogorov-Prandtl parameterization. Approximations of unknown accuracy of the unknown mixing lengths and turbulent kinetic energy are typically constructed by solving associated systems of nonlinear convection-
diffusion-reaction equations with nonlinear boundary conditions. Often these over-diffuse so additional fixes are added such as wall laws or using different approximations in different regions (which must also be specified). Alternately, one can solve an ensemble of NSE's with perturbed data, compute the ensemble mean and fluctuation and simply compute directly the turbulent viscosity parameterization. This idea is recent, seems to be of lower complexity and greater accuracy and produces parameterizations with the correct near wall asymptotic behavior. The question then arises: Does this ensemble eddy viscosity approach over-diffuse solutions? This question is addressed herein.
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Geophysics
Enhanced Seismicity Monitoring in the Rapid Scientific Response to the 2025 Santorini Crisis
Margarita Segou, Foteini Dervisi, Xing Tan et al. (+20 more)
We used a deep learning workflow to enhance earthquake detection during the 2025 seismic unrest between Santorini and Amorgos islands to track the
evolution of the crisis in near real-time. We analysed the continuous seismic waveforms daily (1/2 - 3/3/25) as the crisis unfolded. Our analysis enhanced the earthquake catalogue from around 4,000 to 80,000 earthquakes. The enhanced catalogue allowed this international expert group to identify the volcanic-tectonic character, clearly revealing burst-like, spasmodic seismicity swarms, which is a pattern associated with fluid-driven processes from early stages of the crisis. Detailed moment tensor inversions in early events characterised by a significant non-double couple component indicated the involvement of magmatic or high-pressure hydrothermal fluids driving the unrest. Concurrent DL-enhanced
tomography efforts identified a third, deep magmatic reservoir beneath Anydros Islet, consistent with pressure-driven processes. To date, volcanic-tectonic swarms in which >200 earthquakes of ML > 4 occurred within only a few weeks, largely within episodic bursts of seismicity, have not been observed elsewhere.
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All authors Margarita Segou, Foteini Dervisi, Xing Tan, Rajat Choudhary, Patricia Martínez-Garzón, Francesco Scotto di Uccio, Gregory Beroza, Genny Giacomuzzi, Claudio Chiarabba, Wayne Shelley, Stephanie Prejean, Jeremy Pesicek, John J. Wellik, Marco Bohnhoff, David Pyle, Costas Synolakis, Tom Parsons, Athanassios Ganas, William Ellsworth, Brian Baptie, Gaetano Festa, Piero Poli, Warner Marzocchi
Fluid Dynamics
High-order gas-kinetic scheme for numerical simulations of wind turbine with nacelle and tower using ALM and IBM
Pengyu Huo, Liang Pan, Guiyu Cao et al. (+3 more)
For the first time, the actuator line model (ALM) and the immersed boundary method (IBM) are integrated into the high-order gas-kinetic scheme (GKS) to simulate the wind turbine with the nacelle and tower. The high-order GKS is extended to the simulation of three-dimensional weakly compressible isothermal flows within a well-developed two-stage fourth-order framework. For the wind turbine, the rotor blades are represented by a group of actuator points in ALM, and the nacelle and tower are represented by a group of Lagrangian points in IBM. Both ALM and IBM are integrated through an external body force added in the momentum equation within the high-order GKS. The high-order GKS is implemented on Graphics Processing Units (GPU) to achieve the parallel computing capabilities for the large-scale simulation of turbulent wakes. Turbulent channel flow and turbulent circular cylinder flow are firstly simulated to validate the numerical accuracy of weakly compressible high-order GKS. The NREL 5 MW reference wind turbine is simulated using ALM without the nacelle and tower. Furthermore, the NTNU Blind Test 1 wind turbine is simulated with nacelle and tower using IBM. The current method yields the periodic power and thrust coefficients of the rotor blade due to the blade-tower interactions, while the steady coefficients are obtained when the tower is omitted. Compared to the turbine wakes without the tower, the interaction between tower
vortex and tip
vortex causes an earlier transition. The high-order GKS with ALM and IBM also well predicts the asymmetric mean flows of turbine wake, including the time-averaged streamwise velocity and turbulent kinetic energy, which are in good agreement with NTNU experimental data. The multiple-GPU enabled high-order GKS integrated with ALM and IBM offers an accurate and efficient approach for realistic wind turbine simulations.
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All authors Pengyu Huo, Liang Pan, Guiyu Cao, Baoqing Meng, Baolin Tian, Yubo Huang
Atomic Physics
Atomic data benchmarked by Large-scale Multiconfiguration Dirac-Hartree-Fock Calculations for Beryllium
Sijie Wu, Shaowei Tian, Ran Si et al. (+6 more)
The multiconfiguration Dirac-Hartree-Fock (MCDHF) and relativistic configuration interaction (RCI) methods are used to provide excitation energies, radiative transition data, lifetimes, Lande g-factors, hyperfine interaction constants and isotope shift parameters for the 99 lowest levels of configurations 1s^22snl (n <= 7) + 1s^22p^2 in beryllium. Compared with available experimental excitation energies, the average difference with the standard deviation is 7.08 +/- 1.14cm^-1 (0.011% +/- 0.003%), which demonstrates the excellent theory-observation agreement. The uncertainties of the transition rates are estimated based on two independent methods. The present MCDHF/RCI oscillator strengths and those obtained from the explicitly correlated Gaussian (ECG) method all agree within 2%, except for four transitions affected by strong cancellation effects. For lifetimes, hyperfine splittings and isotope shifts, the present MCDHF/RCI results show good agreement with the few available experimental values, supporting the reliability of our predictions for many states lacking experimental measurements. These comprehensive results can be used in line identification and diagnostics of astrophysical
plasmas.
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All authors Sijie Wu, Shaowei Tian, Ran Si, Kai Wang, Per Jönsson, Gediminas Gaigalas, Michel Godefroid, Anish Mayur Amarsi, Chongyang Chen
Optics
Full-channel wavefront manipulation of surface waves with chirality-assisted geometric-phase metasurface
Shiqing Li, Min Kang, Jianru Li et al. (+11 more)
Owing to their localized field enhancement and subwavelength resolution, surface waves (SWs) offer broad application potential in communications, sensing, and photonics via on-chip wavefront manipulation. This makes multi-channel SW wavefront manipulation highly desirable. However, conventional metasurfaces for SW wavefront shaping, relying on
geometric and propagation phase mechanisms, typically exhibit similar functionalities for co- or cross-polarized output channels under different circularly polarized (CP) incidences, thereby limiting the development of high-capacity on-chip integrated devices. Here, by introducing the chirality-assisted phase as an additional phase control mechanism, we effectively decouple both co- and cross-polarized output channels, enabling independent SW wavefront shaping in four distinct channels. We numerically and experimentally demonstrate two metasurfaces in the microwave range: a four-channel SW meta-deflector and a four-channel SW metadevice that simultaneously produces a focused SW beam, a SW Bessel beam, and two deflected SW beams in different directions. Therefore, chirality-assisted
geometric-phase metasurfaces provide a versatile platform for multi-channel SW wavefront engineering, offering significant potential for high-capacity on-chip communication and integrated photonic systems.
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All authors Shiqing Li, Min Kang, Jianru Li, Yueyi Yuan, Cong Liu, Xiaolong Liu, Juan Deng, Hang Zhang, Jinhua Yan, Linfang Shen, Bo Yan, Kuang Zhang, Lei Zhou, Shulin Sun
Instrumentation and Detectors · Cross-listed from cs.LG
Neural Field Thermal Tomography: A Differentiable Physics Framework for Non-Destructive Evaluation
Tao Zhong, Yixun Hu, Dongzhe Zheng et al. (+2 more)
Inverse problems for stiff
parabolic partial differential equations (PDEs), such as the inverse heat conduction problem (IHCP), are severely ill-posed: the forward map rapidly damps high-frequency interior structure before it reaches the boundary. Soft-constrained physics-informed neural networks (PINNs), which embed the PDE as a residual penalty, suffer from gradient pathology in this regime and tend to fit boundary measurements while leaving the interior field essentially untouched. We propose Neural Field Thermal
Tomography (NeFTY), a hard-constrained neural field framework for label-free three-dimensional inverse heat conduction. NeFTY represents the unknown diffusivity as a continuous coordinate-based neural network, and at every optimization step passes the candidate field through a differentiable implicit-Euler heat solver with harmonic-mean interface flux, so that the governing PDE holds exactly on the discretization rather than as a soft penalty. Adjoint gradients propagate the surface reconstruction error back to the network weights at solver-level
memory cost, making test-time inversion tractable on a single GPU. Across synthetic 3D
benchmarks, NeFTY substantially outperforms soft-constrained PINN variants and a voxel-grid baseline on label-free volumetric recovery, and it transfers to real thermography data, surpassing classical signal-processing baselines in both defect
segmentation and depth estimation. Additional details at https://cab-lab-princeton.github.io/nefty/
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All authors Tao Zhong, Yixun Hu, Dongzhe Zheng, Aditya Sood, Christine Allen-Blanchette
Atomic Physics · Cross-listed from cond-mat.quant-gas
Realizing the Emery Model in Optical Lattices for Quantum Simulation of Cuprates and Nickelates
Hannah Lange, Liyang Qiu, Robin Groth et al. (+7 more)
The microscopic origin of high-temperature superconductivity in cuprates remains one of the central open questions in condensed matter physics. Growing experimental and theoretical evidence suggests that the bare single-band
Fermi-Hubbard model may not fully capture properties of cuprates such as superconductivity, motivating us to revisit the canonical three-band model of the copper-
oxide planes - the Emery model - from which the single-band counterpart was originally derived. Here, we propose and analyze a
quantum simulation scheme for realizing the Emery model in regimes relevant to cuprates and infinite-layer nickelates with today's ultracold atom
quantum simulation platforms, enabling the exploration of the three-band physics on system sizes that are challenging for current numerical methods. Specifically, we show that a two-dimensional optical
lattice with a superimposed pattern of repulsive potentials can be designed to study low-temperature properties for variable parameter regimes of the Emery model relevant to cuprates as well as infinite-layer nickelates. Our results pave the way for real material simulations with ultracold atom
quantum simulators and a better understanding of the physics of unconventional
superconductors.
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All authors Hannah Lange, Liyang Qiu, Robin Groth, Andreas von Haaren, Luca Muscarella, Titus Franz, Immanuel Bloch, Fabian Grusdt, Philipp M. Preiss, Annabelle Bohrdt
Atomic and Molecular Clusters
Light-induced nonadiabatic photodissociation of the NaH molecule including electron-rotation coupling
Zoltán Király, Otabek Umarov, Csaba Fábri et al. (+3 more)
It is well established that electronic conical intersections (CIs) in molecular systems can be induced by
laser light, even in diatomic molecules. The emergence of these light-induced degeneracies leads to strong coupling among electronic, vibrational, and photonic modes, which significantly influences ultrafast
nuclear dynamics. In this work, we perform pump-probe numerical simulations on the NaH molecule, considering the first three singlet electronic states- (X1{\Sigma}+(X), A1{\Sigma}+(A) and B1{\Pi}(B)) -and including several light- induced degeneracies in the theoretical model. To elucidate the ultrafast molecular dynamics, the combined effects of multiple light-induced nonadiabatic couplings and rotational motion of the
nuclei, together with the situation when the electronic angular momentum projected onto the diatomic axis couples with the angular momentum of the
nuclei has been studied. We then calculate key dynamical observables such as dissociation probabilities, kinetic energy release spectra, and angular distributions of the photofragments within and above the linear regime.
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All authors Zoltán Király, Otabek Umarov, Csaba Fábri, Gábor J. Halász, Attila Tóth, Ágnes Vibók
Biological Physics
Surfing on metachronal waves: ciliary transport by inertial coasting
Rafał Błaszkiewicz, Margot Young, Albane Théry et al. (+4 more)
Motile cilia drive biological fluid transport through whip-like beating motions that synchronize into metachronal waves. The lengths of these cilia span three orders of magnitude, from microns in human airways to millimeters in ctenophores. While recent studies have considered ciliary flows at intermediate Reynolds numbers, the effect of inertia on coordinated particle transport remains unexplored. Here, we address this gap using "Pufflets," the inertial counterparts of Stokeslets. These Pufflets describe rapidly accelerating flows generated by short-lived impulses, encoded by spatiotemporally singular momentum injections. To produce such rapid impulses experimentally, we designed an Atwood machine that generates long-lived Pufflet flows, which we capture with high-speed PIV measurements that agree well with analytical theory and simulations. Moreover, we find that pairs of equal and opposite Pufflets can drive net particle displacements and mixing due to time reversal
symmetry breaking, which would be impossible in Stokes flow. Finally, we consider metachronal waves of Pufflets. Remarkably, we discover that particles can surf on these waves by coasting inertially from one cilium to the next, leading to highly efficient particle transport. This work paves the way toward understanding rapidly accelerating flows and collective transport driven by biological and artificial cilia.
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All authors Rafał Błaszkiewicz, Margot Young, Albane Théry, Talia Calazans, Yoichiro Mori, Maciej Lisicki, Arnold J. T. M. Mathijssen
Chemical Physics · Cross-listed from stat.ML
A Tutorial Review of Bayesian Optimization with Gaussian Processes to Accelerate Stationary Point Searches
Rohit Goswami
Building local surrogates to accelerate stationary point searches on potential energy surfaces spans decades of effort. Done correctly, surrogates can reduce the number of expensive electronic structure evaluations by roughly an order of magnitude while preserving the accuracy of the underlying theory, with the gain depending on oracle cost, search distance, and the availability of analytical forces. We present a unified
Bayesian optimization view of minimization, single-point saddle searches, and double-ended path searches: all three share one six-step surrogate loop and differ only in the inner optimization target and the acquisition criterion. The framework uses Gaussian process regression with derivative observations, inverse-distance kernels, and active learning, and we develop optional extensions for production use, including farthest-point sampling with the Earth Mover's Distance, MAP regularization, an adaptive trust radius, and random
Fourier features for scaling. Accompanying pedagogical Rust code demonstrates that all three applications use the same
Bayesian optimization loop, bridging the gap between theoretical formulation and practical execution.
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Space Physics · Cross-listed from cs.LG
Federated Learning-driven Beam Management in LEO 6G Non-Terrestrial Networks
Maria Lamprini Bartsioka, Ioannis A. Bartsiokas, Athanasios D. Panagopoulos et al. (+2 more)
Low Earth Orbit (LEO) Non-Terrestrial Networks (NTNs) require efficient beam management under dynamic propagation conditions. This work investigates
Federated Learning (FL)-based beam selection in LEO satellite constellations, where orbital planes operate as distributed learners through the utilization of High-Altitude Platform Stations (HAPS). Two models, a Multi-Layer Perceptron (MLP) and a Graph Neural Network (GNN), are evaluated using realistic channel and beamforming data. Results demonstrate that GNN surpasses MLP in beam prediction accuracy and stability, particularly at low elevation angles, enabling lightweight and intelligent beam management for future NTN deployments.
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All authors Maria Lamprini Bartsioka, Ioannis A. Bartsiokas, Athanasios D. Panagopoulos, Dimitra I. Kaklamani, Iakovos S. Venieris
Physics Education
Using tablets and smartphones as experimental tools in the physics classroom: effects on learning and motivation
Alice Gasparini, Florian Stern, Marine Delaval et al. (+1 more)
According to the literature, mobile devices as experimental tools (MDET) can offer educational benefits by creating authentic, real-life contexts for physics learning, enhancing student motivation through the use of familiar technology, and supporting cognitive processes by providing multiple representations of phenomena. However, concerns have been raised about potential distractions and cognitive overload. Regarding these conflicting perspectives, few empirical studies on the impact of MDET in real classroom settings of regular, full-length physics courses are available, focusing on a non-specialized high-school target group. We present a study of a mechanics course in such a new setting, addressing the tight curricular, material, and practical constraints inherent to it. A quasi experimental pre post design comparing a treatment group using MDET and a control group without (same content, lesson plan, and teachers) was used. The 19-week teaching sequence focused on conceptual learning and motivational outcomes, controlled by several predictor variables. Findings reveal substantial pre post learning gains for both groups (Cohen d = 0.9) and small gains for perceived relation to reality (d = 0.29). But no significant differences between treatments were found, indicating that MDET do not outperform conventional teaching under the given constraints. Moreover, no evidence of negative effects such as distraction or cognitive overload was observed, and little to no interactions with predictors such as gender or prior knowledge were found. In conclusion, MDET show considerable potential as an effective option for integrating technology into teaching, offering learning outcomes comparable to those of successful conventional teaching, but not better.
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All authors Alice Gasparini, Florian Stern, Marine Delaval, Andreas Müller
Computational Physics · Cross-listed from cond-mat.str-el
Generalized Reduced-Density-Matrix Quantum Monte Carlo Gives Access to More
Zhiyan Wang, Zhe Wang, Bin-Bin Mao et al. (+1 more)
For a long time, people have been focusing on how to extract more information, such as off-diagonal observables, from the
quantum Monte Carlo (QMC) simulation of the partition function, but there have been numerous difficulties, and many of them are insurmountable. In this article, we point out that all the difficulties stem from the starting point of the simulation: calculating a partition function. We introduce a paradigm shift: when we transform the simulated object from a partition function to a generalized reduced density
matrix (GRDM), the difficult problem of measurement can be readily solved. By designing the GRDM, both equal-time and nonequal-time off-diagonal observables have been measured easily in QMC with a
polynomial computation complexity. As a demonstration, the GRDM enables direct access to nonequal-time correlators for dynamical spectra as well as Rényi-1 correlators that reveal strong-to-weak
symmetry breaking in the mixed state, capabilities that lie beyond the reach of prior methods. This establishes a unified framework for
holographic characterization within QMC.
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All authors Zhiyan Wang, Zhe Wang, Bin-Bin Mao, Zheng Yan
Fluid Dynamics
Spectral methods for wedge and corner flows: The Fourier-Kontorovich-Lebedev integral transform
Abdallah Daddi-Moussa-Ider
Understanding fluid flow in wedge-shaped geometries is essential for predicting hydrodynamic interactions in confined systems, such as microfluidic devices and near-corner transport phenomena. This article reviews analytical methods and techniques for addressing wedge problems in low-Reynolds-number hydrodynamics, focusing on solutions of the Stokes equations for a point force (Stokeslet) and a point torque (rotlet). The formulation is based on the Papkovich-Neuber representation, which uses four harmonic functions to characterize the fluid flow. A concise overview of the
Fourier-Kontorovich-Lebedev (FKL) transform method is provided, highlighting key properties and steps employed in deriving these solutions. This offers a versatile framework for predicting particle dynamics in wedge confinements and for designing microfluidic systems with corner geometries.
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Chemical Physics
Nuclear Quantum Effects in Multi-Step Condensed Matter Chemistry: A Path Integral Molecular Dynamics Study of Thermal Decomposition
Jalen Macatangay and Alejandro Strachan
Nuclear quantum effects (NQEs) are often central to a predictive understanding of chemical reactions and rates. While their incorporation in gas-phase reactions is well established, studies involving condensed matter often neglect or approximate such effects. To clarify the role of NQEs in multi-step, multi-molecular reactions in a molecular
crystal, we compare atomistic simulations of the thermal decomposition of the energetic material TATB using path integral molecular dynamics (PIMD), the more approximate
quantum thermal bath (QTB), and classical MD (ClMD). PIMD samples the
quantum canonical distribution by representing each atom as a string of beads (replicas), while QTB uses a frequency-dependent thermostat to reproduce the Bose-Einstein distribution. We find that PIMD results in faster chemical decomposition of the TATB
crystal compared to ClMD, as the initial steps involve hydrogen transfer processes. Interestingly, some of the subsequent reactions (e.g. the formation of N2) occur on identical timescales. The PIMD simulations also predict a reduction in overall activation energy by ~8% as compared to the classical result. As observed in model systems and simple unimolecular gas-phase reactions, the QTB significantly overestimates
quantum acceleration of chemical reactions and the reduction in activation energy. A comparison of the kinetic energy operator in PIMD and the centroid dynamics provides insight into the physics behind the differences between the QTB and PIMD results.
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Applied Physics · Cross-listed from cs.CE
An Atlas of Extreme Properties in Cubic Symmetric Metamaterials
Sahar Choukir, Nirosh Manohara and Chandra Veer Singh
Current research on three-dimensional metamaterial has largely focused on conventional strut, plate, and shell-based
lattice designs. Although these designs offer several advantages, they possess inherent limitations that can restrict their performance in certain applications, motivating the exploration of alternative structural
topologies. Here, we present a large-scale,
symmetry guided framework for the generation and analysis of architected metamaterials based on all 36 cubic space groups. Using a voxel-based representation, we construct a database of approximately 1.95 million periodic unit
cells spanning a broad range of relative densities and topological complexity. This
dataset reveals a rich elastic property landscape shaped by crystallographic
symmetry, including rare pentamode designs with high bulk to shear ratios such as $K/G \approx 166$ , isotropic-auxetic architectures with Poisson's ratio as low as $\nu=-0.76$, and structures achieving up to 93% of the Hashin-Shtrikman upper bound on stiffness. Complementing the
dataset, we develop a three-dimensional convolutional neural network surrogate model trained and evaluated on the full database to predict strain-energy density values under uniaxial, shear, and hydrostatic loading. Together, this work establishes a comprehensive atlas of cubic symmetric metamaterials and provides a pre-trained model for the accelerated discovery and design of 3D architected materials with extreme mechanical properties.
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Chemical Physics · Cross-listed from quant-ph
Variational Adaptive Gaussian Decomposition: Scalable Quadrature-Free Time-Sliced Thawed Gaussian Dynamics
Rahul Sharma and Amartya Bose
Time-slicing has emerged as a strategy for incorporating semiclassical propagation into real-time path integral formulation and recovering full
quantum dynamics. A central step is the decomposition of a time-evolved wave function into a superposition of Gaussian wave packets (GWPs). Here we introduce a quadrature-free variational framework for GWP decomposition, reformulating it as an optimization problem in which the GWP parameters are chosen to maximize the overlap with the time-evolving wave function. An autoencoderdecoder neural network is used for this optimization, with the representation being adaptively reoptimized during propagation. Each wave packet in this decomposition represents a localized patch of the underlying semiclassical
manifold, while retaining full correlations between all degrees of freedom. This variational adaptive Gaussian decomposition (VAGD) approach yields a compact Gaussian expansion, providing a scalable route to time-sliced semiclassical
quantum dynamics. While general, applying VAGD to facilitate time-slicing of thawed Gaussian dynamics allows a route to improving the semiclassical treatment to the full
quantum mechanical result in a systematic manner.
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Optics
VCSEL-Enhanced Holographic Communication for Next-Generation LiFi: State-of-the-Art, Applications, and Future Directions
Hossein Safi, Iman Tavakkolnia and Harald Haas
Light Fidelity (LiFi) has emerged as a promising wireless technology that exploits the vast unlicensed optical spectrum to complement
radio frequency networks. Recent advances in
laser-based transmitters, particularly vertical-cavity surface-emitting
laser (VCSEL) arrays, enable LiFi systems with multi-gigabit data rates, fine-grained spatial multiplexing, and high energy efficiency. However, the highly directional nature of
laser beams introduces new challenges related to user mobility,
alignment, and dynamic environments. This article introduces VCSEL-enabled
holographic communication as a system-level paradigm that addresses these challenges by tightly integrating communication, sensing, and positioning within a single LiFi architecture. The proposed approach leverages individually addressable VCSEL arrays to form a dense grid of controllable beams, while a real-time digital twin of the environment enables adaptive beam management, environmental mapping through sensing, and user localization through positioning, including non-line-of-sight operation. By tightly integrating high-speed data transmission with environmental perception and user tracking, the LiFi access point evolves from a static transmitter into an intelligent environmental hub. The article also provides a tutorial overview of the underlying hardware, system architecture, and operational principles of
holographic LiFi, and discusses key applications, open challenges, and future research directions toward next-generation intelligent optical wireless networks.
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Computational Physics · Cross-listed from cond-mat.mtrl-sci
Sliding Ferroelectricity Driven Spin-Layertronics in Altermagnetic Multilayers
Rui Peng, Guangxu Su, Yangyang Fan et al. (+3 more)
The synergy of ferroicity with altermagnetism offers a novel platform for designing multifunctional altermagnetic-spintronic device technology. In this work, we propose a mechanism to achieve nonvolatile electrical manipulation of
spin and layer degrees of freedom in an altermagnetic
bilayer via sliding ferroelectricity. Using first-principles calculations, we show that an interlayer translation can induce a switchable out-of-plane ferroelectric polarization in
bilayer CuF2, which directly couples to and reverses the d-wave altermagnetic
spin splitting. Notably, the altermangetic
spin splitting is layer-locked, the sliding ferroelectricity-driven switching thus embodying a nonvolatile
spin-layertronics functionality that couples
spin-polarized transport and layer degree of freedom in a single platform. We show that in quadrilayer CuF2, four polarization states are identified which may offer multi-state logic device applications. These findings establish sliding ferroelectricity as a versatile tool for designing voltage-controlled, high-speed and energy-efficient
spin-layertronic devices based on altermagnets.
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All authors Rui Peng, Guangxu Su, Yangyang Fan, Jiaan Li, Fanxin Liu, Yee Sin Ang
Optics
Fast Programming of In-Plane Hyperbolic Phonon Polariton Optics Through van der Waals Crystals using the Phase-Change Material In3SbTe2
Lina Jäckering, Umberto Saldarelli, Aaron Moos et al. (+8 more)
The high directionality of
hyperbolic phonon polaritons (HPhPs) has opened radically new ways to route and steer the flow of energy at the nanoscale. However, launching HPhPs requires fabricating efficient and precisely aligned polariton launching structures, which remains time-consuming and expensive with conventional nanofabrication approaches. Recently, using optical
laser pulses, polariton launching structures have been programmed into the plasmonic phase-change material In3SbTe2. Here, we leverage this approach to reconfigure HPhPs by programming a variety of launching and confining nanostructures through {\alpha}-MoO3 flakes deposited onto In3SbTe2. Importantly, optical programming after flake deposition enables
alignment of launching stripes to the [001]-axis of the flake, essential to control the directional polariton propagation. We showcase these capabilities in a variety of structures: i) an optically programmed disk, showing similar tuning ranges and confinement as focusing by gold disks; and ii) a cavity for in-plane HPhPs created by reconfiguring the single disk to a double disk structure, tailoring the confinement by simply reprogramming the disk distance. Our fabrication scheme offers fast turn-around times, flexible
alignment and the opportunity to reconfigure the structures. Thus, it is a fast, efficient and versatile way to tailor propagation and confinement of highly directional polaritons on demand.
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All authors Lina Jäckering, Umberto Saldarelli, Aaron Moos, Lukas Conrads, Enrique Terán-García, Christian Lanza, Aitana Tarazaga Martín-Luengo, Gonzalo Álvarez-Pérez, Pablo Alonso-González, Matthias Wuttig, Thomas Taubner
Atomic Physics
Calibration of electric fields in low-frequency off-resonant Rydberg receivers
Baran Kayim, Michael A. Viray, David S. La Mantia et al. (+5 more)
We present results on Rydberg atom-based electric field sensing in the range of 1 kHz - 300 MHz, using a three-
photon Rydberg excitation scheme and a transverse electromagnetic (TEM) line waveguide to apply low-frequency rf fields to the
cell. Measurements of low-frequency screening in quartz and sapphire vapor
cells show excellent agreement with a phenomenological model of the effective vapor
cell material properties based on an electrical 2-port measurement of the TEM line. We achieve a best noise-equivalent field of 106(4) $\mathrm{\frac{\mu V}{m \sqrt{Hz}}}$ at 300 MHz and characterize noise-equivalent fields in the ultra-low to very-low frequency (ULF-VLF) band.
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All authors Baran Kayim, Michael A. Viray, David S. La Mantia, Daniel Richardson, James Dee, Ryan S. Westafer, Brian C. Sawyer, Robert Wyllie
Fluid Dynamics · Cross-listed from math.AP
Local-in-Time Existence of $L^1$ solutions to the Gravity Water Wave Kinetic Equation
Yulin Pan and Xiaoxu Wu
In this paper, we study the Cauchy problem for the four-wave kinetic equation describing the weak
turbulence of
gravity water waves. The mathematical challenges of this analysis stem primarily from two interrelated aspects: (1) the extreme algebraic complexity of the collision kernel, where controlling its growth in the highly non-local regime constitutes the primary analytical bottleneck, and (2) the construction of strong solutions under the resulting singular integral operators. First, we re-analyze the interaction kernel in this precise regime, where the interacting wave numbers satisfy $|k|, |k_3| \gg |k_1|, |k_2|$. We establish a rigorous upper bound of $\mathcal{O}(|k||k_3|)$, which rigorously verifies the asymptotic smallness of the interaction coefficient anticipated in the physics literature \cite{zakharov2010energy, geogjaev2017numerical, geogjaev2025properties}. Furthermore, this result improves upon the recent $\mathcal{O}\big((|k||k_3|)^{3/2}\big)$ estimate proposed in \cite{waterkernel2024}, demonstrating a strictly milder singularity of wave interactions in this limit. Physically, this regime governs the energy exchange between disparate scales, such as the modulation of short
gravity waves by long ocean swells. Second, leveraging this crucial integrability gain alongside a refined structural decomposition of the collision operator, we establish the local-in-time existence of $L^1$ strong solutions to the
gravity water kinetic equation for initial data in a suitably weighted $L^2 \cap L^\infty$ space. Specifically, we prove that for any initial data in this class, the resulting $L^1$ strong solution strictly propagates the weighted $L^2 \cap L^\infty$ regularity and conserves the fundamental physical properties of the kinetic model.
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