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Physics Physics

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Sunday 15 March

Applied Physics · Cross-listed from cond-mat.mtrl-sci

Emergent giant topological Hall effect in twisted Fe3GeTe2 metallic system

Hyuncheol Kim, Kai-Xuan Zhang, Yu-Hang Li et al. (+3 more)

The topological Hall effect, driven by the exchange interaction between conduction electrons and topological magnetic textures such as skyrmions, is a powerful probe for investigating the topological properties of magnetic materials. Typically, this phenomenon arises in systems with broken global inversion symmetry, where Dzyaloshinskii-Moriya interactions stabilize such textures. Here, we report the discovery of an emergent giant topological Hall effect in the twisted Fe3GeTe2 metallic system, which notably preserves the general global inversion symmetry. This effect manifests exclusively within a narrow window of "magic" twist angles ranging from 0.45{\deg} to 0.75{\deg}, while it is absent identically outside of that range, highlighting its unique and emergent nature. Micromagnetic simulations reveal that this topological Hall effect originates from a skyrmion lattice induced by alternating in-plane and layer-contrasting Dzyaloshinskii-Moriya interactions that result from local inversion symmetry breaking. Our findings underscore twisted Fe3GeTe2 as a versatile platform for engineering and controlling topological magnetic textures in metallic twisted van der Waals magnets, thereby opening up new avenues for next-generation spintronic devices.
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All authors Hyuncheol Kim, Kai-Xuan Zhang, Yu-Hang Li, Giung Park, Ran Cheng, Je-Geun Park

Fluid Dynamics

Sign-Indefinite Helicity and the Structure of Weak Turbulence in Inertial and Non-Hermitian Waves

Shahaf Aharony Shapira and Michal Shavit

We investigate how sign-indefinite quadratic invariants shape turbulent cascades in incompressible flows with broken time-reversal symmetry, where the dynamics supports strongly anisotropic dispersive waves. Focusing on rotating Euler flow and odd-viscous Euler flow, we isolate the wave component study the corresponding weak-turbulence kinetic equation. We show that helicity conservation substantially simplifies the kinetic equation. Fixing the energy flux by a natural gauge choice, we identify the turbulent spectrum as the unique scale-invariant solution that sustains a constant flux of energy from large to small scales. Under a mild approximation motivated by the accumulation of energy near slow modes, we compute the leading angular dependence and uncover an integrable singularity along the slow-mode curve, that agrees with previous results. We then demonstrate that helicity reorganizes cascade directions at the level of resonant triads. Although helicity is globally sign-indefinite, the helical decomposition splits it into sign-definite contributions on each polarization branch. Triads whose three legs lie on the same branch behave as if constrained by a sign-definite invariant and drive an upscale transfer of energy, producing systematic backscatter even when the net cascade is direct. In the helicity-definite limit (single-branch dynamics), the kinetic equation admits an additional scale-invariant solution associated with helicity transport. Finally, we validate the analytical predictions by numerically evaluating the collision integral in the strongly anisotropic limit, revealing a family of stationary solutions in that regime.
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Instrumentation and Detectors

Beam Test of a SiPM-on-Tile ZDC Prototype with 5.3 GeV Positrons at Jefferson Laboratory

Sean Preins, Weibin Zhang, Ryan Tsiao et al. (+4 more)

We report on a beam test of a Silicon Photo-Multiplier (SiPM)-on-tile Zero Degree Calorimeter (ZDC) prototype developed for the future Electron-Ion Collider (EIC). The detector implements the staggered scintillator-tile geometry envisioned for the final detector and includes 370 instrumented channels, corresponding to O(10%) of the full ZDC. The detector was tested using a 5.3 GeV positron beam at Jefferson Laboratory. We measure the energy response, shower shape, and spatial reconstruction performance of the detector and compare these results with simulation. These studies provide key input for the optimization of the final ePIC ZDC design.
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All authors Sean Preins, Weibin Zhang, Ryan Tsiao, Mia Macias, Brice Saunders, Love Preet, Miguel Arratia

Optics

Minkowski-Space Modeling of Hyperbolic Lenses

Enrico Maria Renzi, Simon Yves, Sveinung Erland et al. (+3 more)

The extreme anisotropy of hyperbolic materials enables extreme wave confinement, but it is also associated with an inherent misalignment between phase and energy flow, which complicates device modeling and design. Here we introduce a Minkowski-space approach to describe hyperbolic wave propagation, showing that this complexity is geometric rather than physical. By embedding anisotropy into an effective Lorentzian metric, we establish a rational design framework for hyperbolic interfaces and lenses, and analytically derive their transfer function and resolution limits, enabling ultra-large numerical apertures and deep sub-diffraction focusing. We validate our theory with the design and full-wave modeling of a planar van der Waals polaritonic lens operating in the mid-infrared frequency range.
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All authors Enrico Maria Renzi, Simon Yves, Sveinung Erland, Diana Strickland, Eitan Bachmat, Andrea Alù

Saturday 14 March

Applied Physics · Cross-listed from eess.SP

Analog Computing with Hybrid Couplers and Phase Shifters

Matteo Nerini, Xuekang Liu and Bruno Clerckx

Analog computing with microwave signals can enable exceptionally fast computations, potentially surpassing the limits of conventional digital computing. For example, by letting some input signals propagate through a linear microwave network and reading the corresponding output signals, we can instantly compute a matrix-vector product without any digital operations. In this paper, we investigate the computational capabilities of linear microwave networks made exclusively of two low-cost and fundamental components: hybrid couplers and phase shifters, which are both implementable in microstrip. We derive a sufficient and necessary condition characterizing the class of linear transformations that can be computed in the analog domain using these two components. Within this class, we identify three transformations of particular relevance to signal processing, namely the discrete Fourier transform (DFT), the Hadamard transform, and the Haar transform. For each of these, we provide a systematic design method to construct networks of hybrid couplers and phase shifters capable of computing the transformation for any size power of two. To validate our theoretical results, a hardware prototype was designed and fabricated, integrating hybrid couplers and phase shifters to implement the $4\times4$ DFT. A systematic calibration procedure was subsequently developed to characterize the prototype and compensate for fabrication errors. Measured results from the prototype demonstrate successful DFT computation in the analog domain, showing high correlation with theoretical expectations. By realizing an analog computer through standard microwave components, this work demonstrates a practical pathway toward low-latency, real-time analog signal processing.
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Geophysics

Hydrodynamics shapes annularity in coral reefs via scale-free growth processes

Eva Llabrés, Àlex Giménez-Romero, Tomàs Sintes et al. (+1 more)

Atolls are traditionally explained as the result of coral reefs accreting around volcanic islands followed by gradual subsidence, yielding a hollow, ring-shaped rim that can extend for kilometres. However, satellite imagery shows that similar annular outlines also appear in much smaller patch reefs, where atoll-forming geological pathways do not apply. In some systems, small annular patches occur within the lagoons of larger atolls, producing nested ring-like patterns. The recurrence of annularity across such contrasting contexts and scales suggests that shared, self-organising processes may also contribute to shaping these reefs. Here, we test whether interactions between reef growth and marine currents can generate annular forms and explain their cross-scale geometric regularities. We develop a numerical model in which coral growth follows simple process-based rules, with local colonisation and mortality depending on resource supply and hydrodynamic stress, and water flow resolved using fluid dynamics. Simulations show that this coupling robustly produces ring-like patch reefs and atoll-like configurations across spatial scales, consistent with observed morphologies. Beyond qualitative agreement, the emergent reefs reproduce key geometric signatures reported in global datasets, including scaling laws and fractal dimensions. Together, these results identify coral-current interactions as a plausible pathway to annular reef formation and a mechanistic explanation for scale-free reef geometry.
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All authors Eva Llabrés, Àlex Giménez-Romero, Tomàs Sintes, Carlos M. Duarte

Chemical Physics

The Python Simulations of Chemistry Framework: 10 years of an open-source quantum chemistry project

Qiming Sun, Matthew R Hermes, Xiaojie Wu et al. (+100 more)

Over the past decade, the Python-based Simulations of Chemistry Framework (PySCF) has developed into a widely used open-source platform for electronic structure theory and quantum chemical method development. This article reviews the major advances since the previous overview in 2020, covering new modules and methodology, infrastructure changes, and performance benchmarks.
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All authors Qiming Sun, Matthew R Hermes, Xiaojie Wu, Huanchen Zhai, Xing Zhang, Abdelrahman M. Ahmed, Juan José Aucar, Oliver J. Backhouse, Samragni Banerjee, Peng Bao, Nikolay A. Bogdanov, Kyle Bystrom, Frédéric Chapoton, Ning-Yuan Chen, Ivan Yu. Chernyshov, Helen S. Clifford, Sander Cohen-Janes, Zhi-Hao Cui, Yann D. Damour, Nike Dattani, Linus Bjarne Dittmer, Sebastian Ehlert, Janus Juul Eriksen, Francesco A. Evangelista, Simon A. Ewing, Ardavan Farahvash, Kevin Focke, Yang Gao, Kevin E. Gasperich, Nathan Gillispie, Jonas Greiner, Matthew R. Hennefarth, Jan Hermann, Christopher Hillenbrand, Joonatan Huhtasalo, Basil Ibrahim, Bhavnesh Jangid, Alireza Nejati Javaremi, Andrew J. Jenkins, Yu Jin, Daniel S. King, Derk Pieter Kooi, Jo S. Kurian, Henrik R. Larsson, Bryan Tak Gwong Lau, Seunghoon Lee, Susi Lehtola, Chenghan Li, Hao Li, Jiachen Li, Rui Li, Shuhang Li, Aleksandr O. Lykhin, Ankit Mahajan, Nastasia Mauger, Pablo del Mazo-Sevillano, Jonathan Moussa, Kousuke Nakano, Verena A. Neufeld, Linqing Peng, Hung Q. Pham, Peter Pinski, Pavel Pokhilko, Zhichen Pu, Yubing Qian, Stephen Jon Quiton, Wanja T. Schulze, Thais R. Scott, Aniruddha Seal, James D. Serna, James E. T. Smith, Kori E. Smyser, Terrence Stahl, Chong Sun, Kevin J. Sung, Egor Trushin, Shiv Upadhyay, Ethan A. Vo, Thijs Vogels, Shirong Wang, Tai Wang, Xiao Wang, Xubo Wang, Yuanheng Wang, Mark Williamson, Junjie Yang, Hong-Zhou Ye, Chia-Nan Yeh, Haiyang Yu, Jincheng Yu, Victor Wen-zhe Yu, Chaoqun Zhang, Dayou Zhang, Yichi Zhang, Zijun Zhao, Zehao Zhou, Andrew J. Zhu, Tianyu Zhu, Timothy C. Berkelbach, Laura Gagliardi, Sandeep Sharma, Alexander Sokolov, Garnet Kin-Lic Chan

Instrumentation and Detectors

Universal method of selective detection of a wide range of pollutants in liquids using conductance quantization

O. Pospelov, A. Herus, A. Savytskyi et al. (+5 more)

The primary objective of research in modern sensor technologies is to develop innovative detection methods for the rapid analysis of complex molecular systems. The present work demonstrates that the quantum mechanism of selective detection, based on conductance quantization, can be effectively employed to create a universal method for detecting a broad spectrum of agents in liquid media, including heavy metals and organic solvents. The efficacy of this approach is illustrated through the use of quantum point-contact sensors, which utilize dendritic Yanson point contacts undergoing quantum transformations during the cyclic switchover effect. These sensors have proven capable of detecting copper, zinc, and lead ions in liquid media across a wide range of concentrations, including trace levels as low as a few parts per billion (ppb). Furthermore, they can identify organic solvents, as demonstrated with acetic acid. The use of innovative quantum detection principles paves the way for the development of a comprehensive array of next-generation devices, offering promising solutions for advanced environmental monitoring applications.
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All authors O. Pospelov, A. Herus, A. Savytskyi, V. Vakula, M. Sakhnenko, N. Kalashnyk, E. Faulques, G. Kamarchuk

Computational Physics · Cross-listed from cond-mat.mtrl-sci

Vacuum Wannier Functions for First-Principles Scattering and Photoemission

Tyler Wu and Tomás Arias

We establish a first-principles theory of vacuum Wannier functions unifying tight-binding and nearly-free-electron descriptions across solid-vacuum interfaces. Analytic solutions for canonical Wannier functions in arbitrary dimension and disentangled functions in 1D motivate a numerically verified 3D Wannier close-packing principle, enabling dense k-space construction of full Born-series scattering states at interfaces and thus predictive photoemission calculations without semiempirical vacuum potentials. Applications to graphene and h-BN reveal corrections beyond the first-Born approximation.
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Chemical Physics

Nonadiabatic rare events from transition-path sampling of MASH trajectories

Danial Ghamari and Jeremy O. Richardson

Rare nonadiabatic reactions are a key component of many important molecular processes but are challenging to capture with direct dynamical simulations. In this paper, we combine our recently developed mapping approach to surface hopping (MASH) with transition-path sampling to create a framework to efficiently simulate these rare events. This is possible because MASH trajectories are Markovian, time-reversible and obey Liouville's theorem. The combined approach generates nonadiabatic reactive pathways without biasing the underlying dynamics. The resulting ensemble allows for a detailed analysis of reaction mechanisms and the unraveling of statistical and dynamical properties, including rate constants. We apply the method to study a spin-boson model in thermal equilibrium over a wide range of diabatic coupling strengths. Our results demonstrate how this approach provides a practical and systematic tool for investigating rare nonadiabatic processes, potentially beyond the reach of brute-force simulations.
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Optics

Beyond optical chirality density: tensor-based description of electromagnetic chirality

Ilia Smagin and Sergey Dyakov

Optical chirality density is widely used as a local scalar measure of the chirality of an electromagnetic field and its interaction with isotropic chiral matter. However, within the dipole approximation, a general bi-anisotropic material response probes direction-dependent field bilinears that cannot, in general, be reduced to a single pseudoscalar. This necessitates the development of a systematic tensorial formulation to describe the coupling between arbitrary fields and general reciprocal bi-anisotropic media. To this end, we extend the Tang–Cohen formalism to a general anisotropic optical-activity pseudotensor, treating its trace and traceless symmetric and antisymmetric parts separately. We demonstrate while the trace part couples to classical optical chirality density, the traceless symmetric part is probed by the five Lipkin densities $Z^{ab0}$, which form part of the Lipkin tensor. On the other hand, for the antisymmetric part of the optical-activity pseudotensor, the coupling term is proportional to the reactive part of the local Poynting vector. Finally, we provide numerical examples of pseudo-chiral and anisotropic chiral electromagnetic fields and study their interaction with different bi-anisotropic media. The developed framework offers a systematic tensorial description of chiral and pseudo-chiral light-matter coupling. Importantly, our analysis identifies which specific field quantities must be enhanced to optimize the magneto-electric coupling in such media.
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Optics

Electron-laser vacuum breakdown in head-on collision of relativistic electrons with intense laser pulse

Pavel Golovinski

The phenomenon of electron-laser vacuum breakdown is the multiple cascade production of electron-positron pairs in head-on collision of a beam of relativistic electrons with an intense laser pulse. This effect was first predicted by the author in 1996 [1] and further developed in [2]. In the present paper, an analytical expression for the total number of produced particles is obtained using the generalized Heitler model. The model results are shown to be in good agreement with the estimates of the pioneering works. An analysis of modern laser facilities (ELI, XCELS, European XFEL, Russian projects) is carried out and estimates of the expected effects are given. At ELI and XCELS class facilities, the quantum nonlinearity parameter can reach 60–150, corresponding to the deeply nonlinear QED regime with multiplicity up to 100 particles per seed electron. Experimental confirmation of the effect is expected in the coming years.
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Optics

Thermally accessible broadband soliton microcombs in silicon carbide enabled by dynamic polarization control

Haoyang Tan, Yi Zheng, Xiyuan Lu et al. (+5 more)

Optical microcombs generated in high-Q microresonators are promising chip-scale light sources for applications ranging from optical communications to spectroscopy and metrology. However, thermo-optic instabilities remain a major obstacle to reliable soliton access. Self-cooling using auxiliary modes can stabilize the intracavity power, yet part of the power is continuously allocated to thermal compensation rather than comb generation, thereby limiting comb power and bandwidth. Here we propose a thermal compensation scheme based on dynamic polarization control. During soliton initiation, a fraction of the pump is coupled to an orthogonally polarized mode to provide self-cooling and ensure reliable soliton access. After soliton formation, polarization rotation and pump tuning transfer this cooling power to the comb-generating mode, enabling efficient single-soliton operation. Using this approach, we experimentally demonstrate a broadband 108-GHz-FSR single-soliton microcomb spanning over 450 nm, together with approximately 39% improvement in the 20-dB bandwidth and 60% increase in comb power relative to the static self-cooling configuration. This dynamic polarization-based thermal compensation enables efficient use of available laser power and provides a practical route to high-performance soliton microcombs in platforms with strong thermo-optic effects.
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All authors Haoyang Tan, Yi Zheng, Xiyuan Lu, Yang Liu, Andreas Jacobsen, Kresten Yvind, Kartik Srinivasan, Minhao Pu

Geophysics · Cross-listed from cs.MS

Pyroclast: A Modular High-Performance Python Solver for Geodynamics

Marcel Ferrari

This monograph presents the design, implementation, and evaluation of Pyroclast, a modular high-performance Python framework for large-scale geodynamic simulations. Pyroclast addresses limitations of legacy geodynamics solvers, often implemented in monolithic Fortran, C++, or C codebases with limited GPU support and extensibility, by combining modern numerical methods, hardware-accelerated execution, and a flexible object-oriented architecture. Designed for distributed and GPU-accelerated environments, Pyroclast provides an accessible and efficient platform for simulating mantle convection and lithospheric deformation using the marker-in-cell method and a matrix-free finite difference discretization. The work focuses on a scalable two-dimensional viscous mechanical solver that forms the computational core for future visco-elasto-plastic models. The solver includes a stress-conservative staggered grid discretization of the incompressible Stokes equations, a matrix-free geometric multigrid solver, Krylov and quasi-Newton methods, and MPI-based domain decomposition for distributed execution. Benchmarks evaluate performance and scalability. Shared-memory tests show strong scaling of the Stokes solver and demonstrate a 5-10x speedup on NVIDIA A100 GPUs compared to a multi-core CPU baseline. Distributed advection benchmarks show near-ideal weak scaling up to 896 CPU cores across seven compute nodes. These results demonstrate that Pyroclast achieves high performance while remaining accessible through a high-level Python interface. The framework also provides a blueprint for modernizing legacy geodynamics codes. Its modular architecture and Python-native implementation lower the barrier to entry while enabling interoperability with modern machine learning libraries, enabling hybrid physics-based and data-driven workflows.
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Computational Physics

Manufacturable blazed metasurface gratings designed by 3D topology optimization model

Simon Ans, Frédéric Zamkotsian and Guillaume Demésy

We present the generalization of our FEM-based topology optimization framework to 3D blazed metasurfaces operating in reflection over the visible and near-infrared range [400-1,500]nm. The design region is described through a density-based SIMP interpolation and optimized using the adjoint method, enabling the treatment of several tens of thousands degrees of freedom. A first approach directly applies topology optimization to the 3D Finite Element mesh (mesh-based), yielding a freeform structure that achieves an average diffraction efficiency of 62% in order -1 over two octaves under the targeted incidence. However, such patterns remain difficult to manufacture. We therefore introduce a pillar-based parameterization, embedding fabrication constraints within the optimization loop. The resulting binary metasurface, compatible with e-beam lithography and Reactive Ion Etching techniques, achieves an average efficiency of 57% over the same spectral band in s-polarization, with low polarization dependence. This work demonstrates that large-scale 3D topology optimization can bridge the gap between broadband optical performance and realistic nanofabrication constraints for blazed metasurfaces.
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Fluid Dynamics

Dynamical compartments in stirred tank reactors and Markov state modeling for mixing quantification: a transfer operator approach

Anna Klünker, Thanh Tung Thai, Eike Steuwe et al. (+4 more)

Identifying coherent flow structures in chemical reactors is crucial for understanding the mixing dynamics, which is essential for optimizing reactor performance. We demonstrate the use of a transfer operator method to find coherent flow structures such as almost-invariant sets and coherent sets, which are characterized by minimal mixing with the surrounding fluid, in a lab-scaled stirred tank reactor using both simulated and experimental Lagrangian trajectory data. The proposed method further enables a detailed analysis of the mixing behavior by computing expected residence times and mixing times. Additionally, a Markov-state-model describes the macroscopic transport dynamics between compartments in the reactor.
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All authors Anna Klünker, Thanh Tung Thai, Eike Steuwe, Christian Weiland, Yvonne Schade, Alexandra von Kameke, Kathrin Padberg-Gehle

Chemical Physics

Systematically Improvable Numerical Atomic Orbital Basis Using Contracted Truncated Spherical Waves

Yike Huang, Zuxin Jin, Linfeng Zhang et al. (+1 more)

To solve the Kohn-Sham equation within the framework of density functional theory, we develop a scheme to construct numerical atomic orbital (NAO) basis sets by contracting truncated spherical waves (TSWs). The contraction minimizes the trace of the kinetic operator in the residual space, generalizing the spillage minimizing scheme [M. Chen et al., J. Phys. Condens. Matter 22, 445501 (2010); P. Lin et al., Phys. Rev. B 103, 235131 (2021)]. In addition to the systematic improvability inherited from previous schemes, the use of TSW instead of plane waves as the expansion basis bridges reference states and NAOs more effectively, and eliminates spurious interactions between periodic images, thereby enabling better transferability through the inclusion of extensive reference states. Benchmarks demonstrate that the constructed NAO achieves satisfactory precision for various properties of both molecules and bulk systems, including total energy, bond length, atomization energy, lattice constant, cohesive energy, band gap, and energy-level alignment. By incorporating unoccupied states, the improved transferability in describing the conduction band is demonstrated to be effective and substantial.
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All authors Yike Huang, Zuxin Jin, Linfeng Zhang, Mohan Chen

Instrumentation and Detectors

Evaluation of polymer-metal-hybrid bonded wafer-stacks and sensor wafers for ultra-thin hybrid silicon detectors

Janna Zoe Vischer, Yannick Dieter, Jochen Dingfelder et al. (+6 more)

Semiconductor pixel detectors are widely established in High Energy Physics (HEP) and Medical physics for their high spatial resolution and tracking capabilities. Research on both monolithic detectors and hybrid detectors is ongoing. Monolithic detectors, which integrate the sensor and the read-out electronics in the same die, provide the benefit of reduced thickness but the needed intricate imaging process is only offered by a limited number of chip vendors. The hybrid approach instead facilitates the design and fabrication of sensor and read-out chip using different technologies and opens up access to a large market of semiconductor vendors. For the production of silicon pixel detectors, the interconnection between sensor and read-out chip is usually realized on an individual die level. The needed mechanical stability during the handling of the dies limits their possible thinness. The wafer-to-wafer interconnection process being developed in this project uses a polymer underfill layer between the wafers to provide additional mechanical stability. This allows one to thin the wafer stack significantly after interconnection, bringing the total thickness close to that of monolithic detectors. In this paper, we present first results on the bump bonding yield of the process based on daisy-chain wafer measurements. For the first hybrid pixel detectors produced with this technique, a dedicated sensor wafer was designed and fabricated to be bonded to Timepix3 read-out chip wafers. Results of the characterization of the sensor wafer before hybridization are presented. We show that the wafer-to-wafer bonding process is suitable for hybrid semiconductor pixel detectors.
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All authors Janna Zoe Vischer, Yannick Dieter, Jochen Dingfelder, Thomas Fritzsch, Fabian Hügging, Kevin Kröninger, Maximilian Mucha, Matthias Schüssler, Jens Weingarten

Classical Physics

About the dissipative Newton equation

Peter Ván

The thermodynamic basis of classical mechanics is presented. In this framework, ideal Newtonian mechanics emerges as the zero-dissipation limit of a more general, dissipative theory. The thermodynamic approach predicts a novel dissipative contribution to the momentum that depends on the applied force, leading to a damping coefficient with a specific, experimentally testable dependence on the inertial mass and the spring constant. A torsion balance experiment with variable moment of inertia has been designed to measure this effect. Several known equations, including a thermodynamic version of the Eliezer-Ford-O'Connell equation of radiation reaction, are recovered as special cases.
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Applied Physics

Nonabelian elastic metamaterials using holonomies acquired by crossing degeneracies

Mohit Kumar, Ralph M. Kaufmann and Fabio Semperlotti

Embedding nonabelian features into elastic metamaterials promises remarkable opportunities for wave control in many practical applications such as surface acoustic wave devices, mode multiplexers, and on-material computation. Nevertheless, current realizations are limited to arrangements of coupled resonators with fine-tuned interactions, limiting their applicability to continuous media. This theoretical and numerical study introduces a design principle for continuous nonabelian elastic metamaterial waveguides. The basic configuration consists of a composite waveguide made of multiple cylindrical waveguides coupled by spatially varying elements. These elements are engineered to follow geometrically-controlled parameter variations that cross selected degeneracies and produce a targeted nonabelian holonomy. The strategy based on crossing degeneracies fundamentally differs from abelian geometric phases, where parameters avoid and encircle degeneracies, or nonabelian Wilczek-Zee phases, where parameters are fine-tuned to maintain degeneracies throughout their cycle. The resulting holonomy transfers an input longitudinal excitation in one rod to an output response in another rod. When two such waveguides are concatenated, their ordering dictates the output response, thereby revealing the emergence of nonabelian dynamics. The nonabelian behavior persists across a broad range of frequencies and under perturbations to the geometry of coupling elements or cylinder diameters. These results establish a robust, effective, and practical route to leverage nonabelian physics in elastic metamaterials.
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Applied Physics

SAGE: Synthetic Aging for a Grid Environment

Paolo Esquivel, Mark A. Harris and Stephen J. Harris

Grid-scale battery degradation unfolds over multi-year timescales under coupled electrochemical, thermal, and operational feedbacks difficult to capture using laboratory data or proprietary field datasets. This scarcity limits the development of degradation-aware algorithms and digital twins that require long-horizon, physically consistent ground truth. Here we present SAGE (Synthetic Aging for a Grid Environment), an open-source, physics-informed simulation framework that generates hour-resolved, multi-decade operating histories and degradation trajectories for heterogeneous battery energy storage system (BESS) fleets. The framework couples stochastic environmental drivers, market-based dispatch, electro-thermal behavior, aging kinetics, and asset-level heterogeneity within a transparent, externally parameterized architecture. We validate physical consistency through hierarchical tests, including Arrhenius temperature acceleration, thermal stratification, and emergent wear-out statistics. Simulations demonstrate how intrinsic heterogeneity in thermal environments and manufacturing naturally produces dispersion in state-of-health trajectories without imposed statistical failure assumptions. SAGE serves as a benchmarking platform for optimization, state estimation, and machine learning, enabling reproducible research in grid-scale energy storage modeling.
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Optics · Cross-listed from quant-ph

Evidence of Uncollapsed Quantum Amplitudes After Consecutive Measurements

Christoph Adami, Lambert Giner, Jeff S. Lundeen et al. (+1 more)

Two of the most common interpretations of quantum measurement disagree about the fate of quantum amplitudes after measurement, yet this disagreement has not previously led to experimentally distinguishable predictions. In the standard collapse picture, commonly linked to the Copenhagen interpretation of quantum mechanics, measurements eliminate unrealized amplitudes without leaving a memory. In contrast, in the unitary theory, the measurement device registers one of the possible outcomes while remaining part of an entangled state that continues to harbor the unrealized amplitudes. This persistence arises naturally under unitary evolution, since a measurement device that is part of an entangled system cannot serve as a faithful probe of the joint quantum state. Using single-photon measurements of a tunable quantum state, we experimentally show that these two theories make different predictions when three or more consecutive measurements are performed on the same quantum system. Analysis of the joint density matrix of the three measurements reveals coherence among them and supports the unitary theory of quantum measurement. When decoherence is explicitly introduced, the joint density matrix of the quantum system of interest and the apparatus becomes consistent with what a collapse theory would predict. This work clarifies the dynamics of consecutive quantum measurements and offers new insights into the interpretation of quantum measurements.
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All authors Christoph Adami, Lambert Giner, Jeff S. Lundeen, Raphael A. Abrahao

Geophysics

Learning relaxation time distributions from spectral induced polarization data with a complex-valued variational autoencoder

Charles L. Bérubé, Sébastien Gagnon, Lahiru M.A. Nagasingha et al. (+4 more)

Spectral induced polarization (SIP) is a geophysical method used to characterize subsurface materials. It measures the frequency-dependent complex electrical resistivity of rocks and soils through the application of an alternating current. Debye and Warburg decompositions are standard methods for analyzing and interpreting SIP data, as they allow estimation of the relaxation time distribution (RTD) of geomaterials. However, conventional decomposition approaches treat measurements independently, work in real-valued spaces despite the complex-valued nature of SIP data, and provide limited uncertainty quantification. These limitations reduce the effectiveness of conventional decomposition on heterogeneous datasets. We reformulate the decomposition approach as an unsupervised machine learning problem and introduce a conditional variational autoencoder (CVAE) that learns a shared mapping from SIP datasets to continuous RTDs. The model is validated on a dataset comprising 140 laboratory and field SIP measurements of granular mixtures, sedimentary and igneous rock, and cementitious materials. The CVAE operates in complex-valued data space and achieves reconstruction errors of 0.53 % and 0.27 % for the imaginary and phase components of resistivity, respectively, with evidence of improvement over conventional methods at corresponding p-values of 0.007 and 0.06. The inferred RTDs are stable and physically consistent, and their total chargeability and mean relaxation time correlate with polarizable grain content and grain size, respectively, with coefficients of determination up to 0.98. An additional contribution of the proposed method is the learned latent representation, which organizes SIP spectra into a structured space. Unsupervised clustering in a two-dimensional projection of this space improves the silhouette score by nearly a factor of two relative to conventional RTD parameters.
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All authors Charles L. Bérubé, Sébastien Gagnon, Lahiru M.A. Nagasingha, Jean-Luc Gagnon, E. Rachel Kenko, Reza Ghanati, Frédérique Baron

Optics

Countershading coloration in blue shark skin emerges from hierarchically organized and spatially tuned photonic architectures inside skin denticles

Viktoriia Kamska, Emeline Raguin, Bodo D. Wilts et al. (+11 more)

The blue shark (Prionace glauca) exhibits a striking dorsoventral color gradient, transitioning from vibrant blue dorsally to silver and white ventrally, a pattern widely interpreted as pelagic countershading. Despite its ecological significance, the physical basis of this coloration remains unresolved. Here we show that this color system does not arise from dermal chromatophores, as in most vertebrates, but from a previously unrecognised photonic architecture housed within the pulp cavity of individual dermal denticles that cover the skin. Optical imaging reveals discrete color domains within denticle crowns, while external denticle morphology remains similar across color zones. Using spectroscopy, micro-computed tomography, histology, and correlative electron microscopy, we demonstrate that color variation is organized across coupled micro- and nanoscale architectures. In blue denticles, iridophores and melanophores form a densely packed tessellated reflector-absorber system within an expanded crown-restricted pulp cavity. Transition-zone denticles exhibit partial cellular layering, whereas white denticles lack melanophores and contain only reflective cells. At the nanoscale, ordered purine-crystal stacks generate narrowband blue reflection, whereas disordered assemblies produce broadband white scattering. Together, these results reveal denticles as mechanically protected optical "pixels" whose hierarchical cellular and nanocrystal organization generates the shark's countershaded coloration.
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All authors Viktoriia Kamska, Emeline Raguin, Bodo D. Wilts, Luca Bertinetti, Chiara Micheletti, Clemens Schmitt, Shahrouz Amini, Maria Murace, Frederik H. Mollen, Michael Blumer, Maite Erauskin Extramiana, Ruien Hu, Stefan Redl, Mason N. Dean

Chemical Physics

Variational Framework for Quantum Molecular Reaction Dynamics

Xingyu Zhang, Jinke Yu and Qingyong Meng

This work describes a geometric framework on molecular reaction dynamics based on the variational principle, where the Schrödinger equation must be solved to “see” how a reaction occurs. First, the mathematical preliminaries are given by discussing the principle of least action and the mountain pass theorem. Second, we discuss the physical preliminaries, including the principle of equivalence for deriving the kinetic energy operator (KEO) and artificial intelligence (AI) techniques to build the potential energy surface (PES) in general spacetime. Moreover, we simplified electromagnetic interactions in curved spacetime within the molecular system and consequently, we are able to construct the nuclear Hamiltonian in nonzero curvature spacetime. This indicates possibility to introduce gauge fields through the curvature, such as additional term in the nuclear KEO near a conical intersection. Third, the single-particle approximation provides a powful ansatz to solve the Schrödinger equation by variational principle. Thus, one can formulate the variational approaches for either electronic structure or quantum dynamics. In this work, based on previous discussions (Phys. Chem. Chem. Phys. 27 (2025), 20397) we unified them by a geometric description, where the geometric phase is naturally introduced. Finally, due to optimization characteristic of the present theory, further discussions on the present theory from optimization insight are also given, including two postulates, generative AI techniques, role of perturbation, and Markov process in optimization.
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Plasma Physics · Cross-listed from astro-ph.SR

Formation and rising phase of a flux rope through data-constrained simulations

M. V. Sieyra, A. Strugarek, A. Prasad et al. (+8 more)

Context. Data-constrained models incorporate observed photospheric magnetic fields. However, due to the lack of magnetic field information in the rest of the solar atmosphere, models rely on extrapolations that, in most cases, neglect the Lorentz force. Nevertheless, this force is present in the lower atmosphere and may play a key role in destabilising the equilibrium configuration and triggering eruptions. Aims. This study seeks to understand and reproduce a solar eruption SOL2014-12-18T21:41 that occurred in active region NOAA 12241, preceded by an M6.9 flare, and to investigate the impact of relaxing the initial force-free assumption. Methods. The resistive and compressible magnetohydrodynamic simulation is initiated using a non-force-free magnetic field extrapolated from a photospheric vector magnetogram taken minutes before the flare. The simulation includes a stratified atmosphere and non-ideal effects such as thermal conduction and radiative cooling. Results. A flux rope forms and rises in the simulation, carrying away dense material from the lower solar atmosphere. Its formation results from the non-zero Lorentz force acting on the initial sheared arcade, without assuming pre-existing flux ropes or photospheric driving motions. The flux rope is then deflected toward regions of low magnetic pressure, escaping the domain at 350 km/s with approximately constant acceleration. Conclusions. A robust numerical framework for modelling flaring active regions was applied to the eruption of NOAA AR12241 as a case study, assuming a realistic non-force-free magnetic field near the flare onset. It exemplifies how an initial Lorentz force imbalance can successfully trigger a flux rope formation that later escapes the simulation domain. It also enables comparison with real observations through the addition of a stratified atmosphere spanning from the photosphere to the corona.
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All authors M. V. Sieyra, A. Strugarek, A. Prasad, A. Wagner, P. Démoulin, F. Moreno-Insertis, A. J. Finley, R. Joshi, A. Blaise, A. S. Brun, E. Buchlin

Atmospheric and Oceanic Physics

Observation of stable components of the sound field in Lake Kinneret using the autoproduct transform

A.L. Virovlyansky

An analysis was conducted of broadband sound pulses received by a vertical array in Lake Kinneret (Israel). For most frequencies within the pulse frequency bands, the array is sparse. The application of the autoproduct transform made it possible to approximately reconstruct the signals that would be received after the emission of pulses at low frequencies for which the array is dense. Using the coherent state method developed in quantum theory, a transition has been made from representing the reconstructed field as a function of depth and time to its distribution in the 'depth-angle-time' phase space. Due to the absence of multipath, the intensity distribution in this space should be weakly sensitive to variations in environmental parameters. In accordance with this expectation, the distribution found is close to the result of its calculation using an idealized (range-independent) waveguide model. It has been shown that this intensity distribution can be used as input data for a neural network when solving the problem of sound source localization in an underwater waveguide. In the examples considered, the neural network is trained on synthetic data, i.e., data obtained from theoretical calculations.
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Atmospheric and Oceanic Physics

Testing a hydroacoustic radiator in a reverberant tank based on recording the sound field in the air above the tank

A.L. Virovlyansky, M.S. Deryabin, A.A. Prokhorov et al. (+2 more)

A method for calibrating a monopole sound source in a water tank with reflective side walls and bottom is considered. The idea of the method is based on the phenomenon of anomalous transparency of the water-air boundary for a sound source located at a shallow depth. This boundary plays the role of a filter that prevents waves reflected from the side walls and bottom from entering the air. For a shallow source, the field in the air will be approximately the same as for a source located at the same depth in a homogeneous water half-space. This field is described by a well-known analytical formula that makes it possible to estimate the source strength in water based on the sound intensity level measured in air.
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All authors A.L. Virovlyansky, M.S. Deryabin, A.A. Prokhorov, A.Yu. Kazarova, V.K. Bakhtin

Computational Physics · Cross-listed from cond-mat.stat-mech

Information-Driven Phase Transition on Weighted Graphs with Spontaneous Dimensional Sensitivity

Valerio Dolci

We study information flow on a weighted graph whose topology evolves according to a spectral curvature measure $\mathcal{R}$. The model (FIU) defines $\mathcal{R}$ from the diagonal of the graph Green function, propagates energy with curvature-dependent dissipation, and creates long-range links between high-$\mathcal{R}$ nodes at a rate controlled by a coupling parameter $g$. We report three results. First, the system exhibits a sharp phase transition at $g_c \approx 0.023$: below $g_c$, local information flux $\sigma$ and structure formation are anti-correlated; above $g_c$, they become strongly correlated (Pearson $r \approx 0.75$, $p < 10^{-38}$), with signatures of a continuous transition and mean-field exponent $\nu \approx 0.54$. Second, we identify a node-level discrete Poisson relation $\nabla^2\mathcal{R}(i) = \kappa\,\sigma_{\rm prev}(i)$, where $\kappa$ is stable across parameters (CV $= 3.1\%$ across independent configurations). Mediator analysis reveals this correlation is almost entirely mediated by $\mathcal{R}$ itself, identifying it as the central self-organizing variable. Third, the Poisson relation exhibits spontaneous dimensional sensitivity: in 2D lattices both signals decay for $N \gtrsim 576$, while in 3D they persist to $N \lesssim 1728$. This emerges without any dimensional parameter in the rules. The collapse mechanism is curvature homogenization at large $N$. We interpret this as topological frustration in a mesoscopic regime, and discuss analogies with dimensional signatures of gravity.
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Optics

Design of Angular-offset Interstitial-Tube- Assisted Hollow-Core Fibers with Ultrahigh Mode Purity and Ultralow Loss

Hao Chen, Jiayi Chen, Dawei Ge et al. (+5 more)

Antiresonant hollow-core fibres (AR-HCFs) have recently reached attenuation far below the Rayleigh-scattering limit of silica, but their inherently multimode nature remains a major challenge for practical systems requiring high modal purity. In particular, suppressing higher-order modes (HOMs) at the 1 dB/m level while maintaining sub-0.1 dB/km fundamental-mode (FM) loss is difficult because conventional filtering strategies rely on tuning nested-tube dimensions, a design freedom that becomes increasingly restricted in the ultralow-loss regime. Here, we propose a new HOM-control mechanism in an interstitial-tube-assisted double nested anti-resonant nodeless fiber (IT-DNANF) by introducing angular offset of the interstitial tubes. Instead of using nested cavities as the primary tuning element, the proposed approach exploits the gap region between adjacent cladding tubes as a leakage-adjacent modal-control interface. Numerical simulations show that the offset increases both FM and HOM losses, but with a substantially stronger sensitivity for HOMs, leading to rapid enhancement of differential modal loss. Furthermore, when the gap-region FM is tuned into phase matching with the core HOM, strong coupling to a high-leakage state is induced, resulting in a pronounced HOM-loss peak. Using the practical criterion of HOM losslarger than 1 dB/m, we identify optimized IT-DNANF designs that achieve rapid HOM stripping while maintaining FM loss below 0.05 dB/km at 1550 nm. This work establishes angular offset as a physically distinct and manufacturability-friendly degree of freedom for mode purification in ultralow-loss hollow-core fibres.
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All authors Hao Chen, Jiayi Chen, Dawei Ge, Dong Wang, Shoufei Gao, Wei Ding, Dechao Zhang, Yingying Wang