Chemical Physics
Nuclear Spin Isomers and the Pauli Principle in Polaritonic Chemistry
Csaba Fábri, Gábor J. Halász, Lorenz S. Cederbaum et al. (+1 more)
The Pauli principle has far-reaching consequences in
quantum physics. Here, we investigate, for the first time, its implications, together with
nuclear spin isomerism, in polaritonic chemistry. The theory is developed for a single and a few molecules as well as for an ensemble of molecules. As an explicit and detailed example we first present an accurate numerical description of a realistic situation involving two $^{14}$NH$_3$ molecules, existing as ortho and para
spin isomers, in an infrared plasmonic cavity. Then, we generalize the approach for molecular ensembles using analytical considerations based on the Tavis-Cummings model and simulate the transmission spectrum of a Fabry-Pérot cavity filled with $^{14}$NH$_3$ gas using
quantum mechanics. These results are directly relevant for recent gas-phase experiments studying rovibrational polaritons in molecules. Our findings undoubtedly demonstrate that the Pauli principle and
nuclear spin isomerism significantly reshape collective light-matter coupling involving molecules with identical
nuclei.
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All authors Csaba Fábri, Gábor J. Halász, Lorenz S. Cederbaum, Ágnes Vibók
Medical Physics
Model-aided quantification of patient-specific benefit in mitigating radiation induced lymphopenia by particle therapy of cancer
Vladislav Sandul, Marco Durante and Thomas Friedrich
Treatment-related lymphopenia is a frequent and clinically significant consequence of cancer therapy that can compromise immune-mediated tumor control and worsen patient outcomes. Despite its importance, no mechanistic framework exists to accurately predict the severity of lymphopenia from patient-specific data. Here, we present a biokinetic model that quantitatively describes lymphocyte depletion and recovery during and after radiotherapy, integrating radiation dose-volume distributions, blood circulation dynamics, and distinct kinetics of fast- and slow-recovering lymphocyte populations. The model was calibrated and validated using 56 independent clinical
datasets encompassing various tumor sites and treatment modalities. It reproduces observed lymphocyte counts and enables prediction of individual severity of lymphopenia from baseline or early-treatment counts. Applying this framework, we demonstrate that particle therapy reduces lymphocyte depletion by ~30% compared with
photon therapy, providing a quantitative explanation for its observed immune-sparing benefit. By linking radiation physics, immune kinetics, and clinical outcomes, our model establishes a mechanistically grounded predictive approach for anticipating systemic immune toxicity. Beyond radiotherapy, this framework offers a generalizable strategy for integrating early biological markers into treatment optimization, advancing personalized and immune-preserving cancer therapy.
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Accelerator Physics
Achromatic Telescopic Squeezing for Dynamic Aperture Optimization in the Electron Storage Ring of the EIC
Jonathan Unger and Georg Hoffstaetter
We investigate the application of the Achromatic Telescopic Squeezing (ATS) scheme to the Electron Storage Ring (ESR) of the Electron-Ion
Collider (EIC) as a method to improve dynamic aperture and momentum acceptance. A comparative study is performed between conventional sextupole correction schemes and ATS-based optics using both a simplified test
lattice and the full ESR
lattice. We show that ATS optics can reduce the required sextupole strengths and mitigate higher-order nonlinear effects, leading to improved momentum aperture. With the ATS principle one could reduce the number of sextupoles in an arcs by a factor of two while maintaining similar momentum aperture. We additionally show a scheme utilizing all sextupoles which provides an advantage in momentum aperture. While the resulting ATS optics provides a measurable increase in momentum acceptance ($\sim$0.1% under the test conditions), it also induces emittance growth due to increased $\beta$-functions in the arcs. This trade-off limits its applicability for the ESR but suggests potential advantages for storage rings where moderate emittance growth is acceptable.
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Accelerator Physics
High temporal resolution THz streaking of high brightness relativistic electron beams
Maximilian Lenz, Brian Schaap, Atharva Kulkarni et al. (+4 more)
We report a systematic experimental study of terahertz (THz) streaking structures for ultrafast characterization of relativistic, high-brightness electron beams. Horn-coupled waveguide geometries are investigated, enabling a comparative characterization of streaking strength, dispersion, transmission, and temporal fidelity. Analytical models and electromagnetic simulations are used to describe the dependence of streaking power on the waveguide dimensions and the drive frequency. Experimentally, the structures are characterized using compressed electron beam from an RF photoinjector over a range of THz field strengths, beam energies, and bunch durations. These results establish general design principles and performance limits for THz streaking structures applicable to ultrafast electron beam diagnostics.
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All authors Maximilian Lenz, Brian Schaap, Atharva Kulkarni, Yuemei Tan, Yining Yang, Renkai Li, Pietro Musumeci
Optics
Cryogenic Graphene-Based Phase Modulators for Quantum Information Processing
Leonard Barboza Navarro, Maria Carolina Volpato, Alisson Ronieri Cadore et al. (+1 more)
Electro-optic modulators are key components for photonic
quantum computing, particularly in fully cryovenic integrated platforms where low loss and compactness are critical. We present a systematic theoretical investigation of compact dual-layer
graphene (DSLG) electro-optic phase modulators integrated on silicon nitride waveguides, with emphasis on cryogenic operation. By combining electromagnetic simulations with a physically consistent description of
graphene conductivity based on the Kybo formalism, we analyze the interplay between electrostatic tuning, optical mode confinement, and material-dependent losses. We show that cryogenic operation enhances device performance by sharpening the
Fermi-Dirac distribution, enabling access to the Pauli-blocking regime at lower
Fermi levels and reducing the required modulation length. Through optimization of the waveguide geometry, dielectric spacer thickness and permittivity, and
graphene quality, we identify regimes that simultaneously minimize insertion loss and device footprint under realistic voltage constraints. The optimized designs achieve near-pure phase modulation with insertion losses below 0.3 dB and modulation lengths below 50 um at 10 K, while maintaining GHz-scale bandwidths. These results provide quantitative design guidelines for low-loss, compact, cryogenic
graphene phase modulators for scalable integrated
quantum photonics.
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All authors Leonard Barboza Navarro, Maria Carolina Volpato, Alisson Ronieri Cadore, Pierre-Louis de Assis
Physics and Society
Urban Science Beyond Samples: Up-to-Date Street Network Models and Indicators for Every Urban Area in the World
Geoff Boeing
Urban planners need up-to-date, global, and consistent street network models and indicators to measure resilience and performance, model accessibility, and target local quality-of-life interventions. This article presents up-to-date street network models and indicators for every urban area in the world. It uses 2025 urban area boundaries from the Global Human Settlement Layer, allowing users to join these data to hundreds of other urban attributes. Its workflow ingests 180 million OpenStreetMap nodes and 360 million OpenStreetMap edges across 10,351 urban areas in 189 countries. The code, models, and indicators are publicly available for reuse. These resources unlock worldwide urban street network science beyond samples as well as local analyses in under-resourced regions where models and indicators are otherwise less-accessible.
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Optics · Cross-listed from quant-ph
Nonreciprocity-enriched steady phases in open quantum systems
Ding Gu, Zhanpeng Fu and Zhong Wang
Nonreciprocity can profoundly alter the spectra and dynamics of open
quantum systems, yet its impact on the long-time steady-state phases of matter has remained largely unexplored. Here we show that the interplay of nonreciprocity,
symmetry defects, and spatial boundaries can generate phases beyond the standard spontaneous-
symmetry-breaking paradigm. We demonstrate this mechanism by showing that sufficiently strong nonreciprocity turns boundaries into sources and drains of
symmetry defects, while simultaneously endowing these defects with
chiral dynamics in the bulk. As a result, the conventional uniform
symmetry-broken state gives way to a domain-wall traveling-wave phase, in which
symmetry defects form a persistent
chiral wave. We showcase this mechanism in a bosonic model with \(Z_{2}\)
symmetry, where periodic boundary conditions support only the conventional symmetric and
symmetry-broken phases, whereas open boundary conditions allow the traveling-wave phase. We further show that even in the absence of
symmetry breaking, the steady state can exhibit anomalous
chiral relaxation: owing to the non-Hermitian skin effect in the stability
matrix, local fluctuations are chirally amplified as they approach a boundary, where they eventually decay. Combining mean-field theory with truncated Wigner simulations, we characterize these phases, analyze the order parameter and Goldstone-mode fluctuations of the traveling-wave phase, and confirm its existence in three spatial dimensions.
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Plasma Physics · Cross-listed from cs.LG
Human-in-the-Loop Meta Bayesian Optimization for Fusion Energy and Scientific Applications
Ricardo Luna Gutierrez, Sahand Ghorbanpour, Rahman Ejaz et al. (+5 more)
Inertial Confinement Fusion (ICF) holds transformative promise for sustainable, near-limitless clean energy, yet remains constrained by prohibitively high costs and limited experimental opportunities. This paper presents Human-in-the-Loop Meta
Bayesian Optimization (HL-MBO), a framework that integrates expert knowledge with few-shot, uncertainty-aware machine learning to accelerate discovery in data-scarce, high-stakes scientific domains. HL-MBO introduces a meta-learned surrogate model with an expert-informed acquisition function to recommend candidate experiments. To foster trust and enable informed decisions, HL-MBO also provides interpretable explanations of its suggestions. We show HL-MBO outperforms current BO methods on ICF energy yield optimization, as well as
benchmarks in molecular optimization and critical temperature maximization for superconducting materials.
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All authors Ricardo Luna Gutierrez, Sahand Ghorbanpour, Rahman Ejaz, Varchas Gopalaswamy, Riccardo Betti, Vineet Gundecha, Aarne Lees, Soumyendu Sarkar
Applied Physics · Cross-listed from cond-mat.mtrl-sci
Uniaxial strain-driven ferroelastic domain control in LaAlO3
Matthias Roeper, Robin Buschbeck, Jakob Wetzel et al. (+15 more)
Multiferroic domain walls in functional
oxides exhibit properties distinct from the bulk and are increasingly exploited as active elements in nanoelectronic and photonic devices. Deterministic control of domain populations has typically remained limited to local control, or removal with temperature. Here we demonstrate continuous, reversible manipulation of the ferroelastic domain structure in single-
crystal LaAlO$_3$ using in-situ uniaxial strain. Combining atomic force microscopy, X-ray diffraction, and Raman spectroscopy with first-principles calculations we map the complete microscopic
evolution of the twin domain population through the strain-driven transition from the rhombohedral $R\bar{3}c$ ground state toward the predicted orthorhombic $Fmmm$ phase. Applied strains below $0.5\%$ produce pronounced surface flattening and large-scale domain reorganisation, establishing uniaxial strain as a technically accessible control parameter for ferroelastic domain engineering. These results open a route to active, real-time programming of domain architectures in LaAlO$_3$-based
heterostructures, with implications for strain-tunable superconducting interfaces, nanoscale
phonon-polariton optics, and ultrafast
lattice control.
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All authors Matthias Roeper, Robin Buschbeck, Jakob Wetzel, Tobias Ritschel, Anna-Lena Hofmann, Vladyslav Kovtunovych, Mike N. Pionteck, Javier Taboada-Gutiérrez, Alexey B. Kuzmenko, Martina Basini, Vivek Unikandanunni, Iuliia Kiseleva, Jochen Geck, Susanne C. Kehr, Maximilian Lederer, Simone Sanna, Lukas M. Eng, Samuel D. Seddon
Physics and Society
Phase Transitions in Economic Inequality:Taxation and Extremal Replacement Dynamics
Lautaro Giordano, Sebastian Gonçalves, José Roberto Iglesias et al. (+1 more)
We present a minimal
agent-based model of interacting
agents characterized by their wealth to study taxation and inequality in a non-conservative economy. Wealth evolves through an extremal
stochastic replacement process in which the poorest
agent has its wealth replaced by a new random value, financed through a collective taxation mechanism. We explore taxation regimes ranging from regressive to progressive schemes and tune the overall redistribution strength. Under regressive taxation, the system self-organizes into two distinct stationary phases when changing the total tax collected: a non-ergodic, high-inequality regime characterized by wealth condensation in a subset of
agents that permanently escape replacement, and a more homogeneous ergodic phase in which all
agents participate in the dynamics. Increasing taxes drives an abrupt transition between these phases. The transition is discontinuous and exhibits hysteresis and bistability, consistently detected through the Gini index, the Top $1\%$ wealth share, the
entropy, and the Binder cumulant. In contrast, neutral and progressive taxation suppress persistent wealth concentration, preventing the emergence of strongly unequal states and eliminating hysteretic behavior. We complement the simulations with a parameter-free mean-field theory of the wealth dynamics that reproduces the stationary distributions and explains the transition by locating the two spinodals that bound the bistable region. These results show that minimal
stochastic redistribution mechanisms alone can produce discontinuous transitions, metastability, and non-ergodicity, demonstrating that taxation structure can determine the emergence and stability of macroscopic inequality.
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All authors Lautaro Giordano, Sebastian Gonçalves, José Roberto Iglesias, María Fabiana Laguna
Plasma Physics
Determination of turbulent heating rate and relaxed states in finite Larmor radius magnetohydrodynamic turbulence with helicity barrier
Ramesh Sasmal and Supratik Banerjee
Finite Larmor radius magnetohydrodynamics (FLR-MHD) provides a hybrid model of
plasma that explains how turbulent energy cascade extends to sufficiently small parallel length scales, potentially leading to perpendicular heating of the ions in the
solar corona and the
solar wind. In this work, we derive exact laws for the cascades of energy and generalized helicity in fully developed FLR-MHD
turbulence. In large and small scale limits, we obtain the exact laws for reduced MHD and electron reduced MHD
turbulence respectively. Unlike ordinary or reduced MHD
turbulence, a global stationary state is shown to be absent in the case of a strong imbalance between the Elsasser variables. This is due to the so-called helicity barrier, which leads to two separate stationary energy cascades with different cascade rates. Our derived exact laws enable us to calculate these two cascade rates and therefore their difference, which effectively provides the heating rate of the ions. In addition, we also derive alternative Banerjee-Galtier forms for the exact laws and hence obtain the relaxed states of FLR-MHD
turbulence using the framework of recently proposed principle of vanishing nonlinear transfer. The relaxed states show
alignment between the velocity and
magnetic field fluctuations. However, due to strong anisotropy, no Beltrami
alignment is possible for velocity and
magnetic fields. Similarly to the exact laws, the relaxed states of reduced and electron reduced MHD emerge in the large and small scale limits, respectively.
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Fluid Dynamics · Cross-listed from math.NA
Beyond first-order accuracy in continuous-forcing immersed boundary methods, and their well-conditioned projection-based solution
Diederik Beckers, H. Jane Bae and Andres Goza
We introduce a refined immersed boundary (IB) methodology that is better-than-first-order accurate in practice, while preserving key properties of "continuous-forcing" IB approaches that retain a singular source term in the governing equations. Our method leverages a smoothed indicator (Heaviside) function, following ideas from multiphase flow and immersed layers formulations, to recast the IB solution as a composite of distinct interior and exterior fields. We demonstrate that, when cast through this composite-solution lens, prior continuous-forcing IB methods can be seen as neglecting terms in the governing and constraint equations that restrict the solution to first-order accuracy. We incorporate these terms to systematically improve accuracy without the need for heuristic corrections. In canonical Poisson problems, we empirically demonstrate second-order convergence, and in incompressible Navier-Stokes simulations the method achieves slightly sub-second-order performance. While our present study focuses on these cases, the framework suggests a path towards second-order accuracy or higher, with further extensions. This perspective reframes accuracy limitations typically attributed to IB schemes. Although continuous-forcing IB methods are often reported to be only first-order accurate, we show that neither smoothing nor interface interpolation inherently restricts attainable order. Moreover, we naturally incorporate this higher-order formulation into a projection-based solution process. The resulting
algorithm simultaneously mitigates the spurious surface stresses produced by ill-conditioned linear systems and reduces sensitivity to
geometric resolution, addressing both conditioning and accuracy concerns within a unified approach.
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Instrumentation and Detectors · Cross-listed from cs.RO
Design and Characteristics of a Thin-Film ThermoMesh for the Efficient Embedded Sensing of a Spatio-Temporally Sparse Heat Source
Sajjad Boorghan Farahan, Ahmed Alajlouni and Jingzhou Zhao
This work presents ThermoMesh, a passive thin-film thermoelectric mesh sensor designed to detect and characterize spatio-temporally sparse heat sources through conduction-based thermal imaging. The device integrates thermoelectric junctions with linear or nonlinear interlayer resistive elements to perform simultaneous sensing and in-sensor compression. We focus on the single-event (1-sparse) operation and define four performance metrics: range, efficiency, sensitivity, and accuracy. Numerical modeling shows that a linear resistive interlayer flattens the sensitivity distribution and improves minimum sensitivity by approximately tenfold for a $16\times16$ mesh. Nonlinear temperature-dependent interlayers further enhance minimum sensitivity at scale: a ceramic negative-temperature-coefficient (NTC) layer over 973-1273K yields a $\sim14{,}500\times$ higher minimum sensitivity than the linear design at a $200\times200$ mesh, while a VO$_2$ interlayer modeled across its metal-
insulator transition (MIT) over 298-373K yields a $\sim24\times$ improvement. Using synthetic 1-sparse
datasets with white boundary-channel noise at a signal-to-noise ratio of 40dB, the VO$_2$ case achieved $98\%$ localization accuracy, a mean absolute temperature error of $0.23$K, and a noise-equivalent temperature (NET) of $0.07$K. For the ceramic-NTC case no localization errors were observed under the tested conditions, with a mean absolute temperature error of $1.83$K and a NET of $1.49$K. These results indicate that ThermoMesh could enable energy-efficient embedded thermal sensing in scenarios where conventional infrared imaging is limited, such as molten-droplet detection or hot-spot monitoring in harsh environments.
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Computational Physics · Cross-listed from quant-ph
Quantum Lattice Boltzmann Solutions for Transport under 3D Spatially Varying Advection on Trapped Ion Hardware
Sayonee Ray, Jezer Jojo, Jason Iaconis et al. (+5 more)
The
Quantum Lattice Boltzmann Method (QLBM) has emerged as one of the most promising
quantum computing approaches for the numerical simulation of problems in computational fluid dynamics (CFD). The dynamics is formulated in terms of mesoscopic particle distribution functions governed by a discrete Boltzmann transport equation, comprising local streaming and collision operations. In this work, the resulting macroscopic behavior corresponds to the advection-
diffusion equation, which we adopt as a canonical model problem for transport phenomena. Building upon recent progress in QLBM implementations, we advance towards more realistic problem settings that better reflect conventional CFD requirements. We address, for the first time, transport under the action of non uniform velocity fields on
quantum hardware. We implement our demonstration using IonQ's trapped-ion systems including Forte generation systems and a 64-
qubit Barium development system similar to the forthcoming IonQ Tempo line. We identify the density readout and subsequent reloading of the fluid density as a potential bottleneck of the current
algorithm and discuss several approaches to mitigate this bottleneck. We identify the use of MPS shadow
tomography as a promising method to efficiently scale the readout to large system with complex density distributions. Lastly, we introduce and simulate a novel method to implement wall boundaries for advection-
diffusion in QLBM, and discuss the prospects of scaling to higher-complexity problems.
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All authors Sayonee Ray, Jezer Jojo, Jason Iaconis, Abeynaya Gnanasekaran, Apurva Tiwari, Martin Roetteler, Chris Hill, Jay Pathak
Chemical Physics · Cross-listed from cond-mat.mtrl-sci
Machine Learning and Molecular Simulations Reveal Mechanisms of ZIFs Polymorph Selection
Emilio Méndez and Rocio Semino
Zn(imidazolate)$_2$ metal-organic frameworks (MOFs) exhibit a remarkable degree of polymorphism. Because of their promising industrial applications, many research groups have investigated phase transitions, phase diagram and relative stability of these polymorphs. There is now wide consensus in the research community that these MOFs are solvothermally formed via non-classical nucleation mechanisms, in which pre-nucleation clusters are first formed, followed by an intermediate amorphous structure that subsequently reorganizes to yield the final crystalline MOF. However, no study up to date has uncovered which part of the synthesis process determines the final polymorph obtained. In this work, path collective variable metadynamics simulations performed with a partially reactive force field give insights into mechanistic and thermodynamic aspects of the self-assembly of these MOFs. Databases of transient and intermediate synthesis structures are built from the simulations. By developing and applying neural network classifiers over these databases, it is found that both pre-nucleation clusters and the amorphous intermediate structures are polymorph-dependent. These results suggest that polymorph selection happens as early as the pre-nucleation cluster stage.
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Applied Physics · Cross-listed from cond-mat.mtrl-sci
Radio Frequency Field-Induced Enhancement of Detection Sensitivity in Silicon Nanowire Sensors
Ang Liu, Jingsong Shang, Jiangang J. Du et al. (+2 more)
Sensitive biomarker detection in physiological fluids is often limited by Debye screening, which suppresses electrostatic signals at sensor surfaces. Here we report a sensing approach based on flexoelectric resonance in silicon nanowire field-effect transistors. An applied radiofrequency field induces strain gradients in the nanowires, generating flexoelectric polarization that is amplified at resonant frequencies. This effect enhances the sensitivity of conductance measurements to small surface charge variations associated with biomolecular binding. Using C-reactive
protein as a model biomarker, we observe an order-of-magnitude improvement in detection sensitivity compared to conventional operation, with a 62% conductance increase versus 30% without radiofrequency modulation. The high-frequency field also perturbs the electrical double layer, reducing Debye screening in high-ionic-strength environments. These combined effects enable direct biomarker detection without sample dilution. This work establishes flexoelectric resonance as a general strategy for improving nanoscale biosensing performance in physiologically relevant conditions.
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All authors Ang Liu, Jingsong Shang, Jiangang J. Du, Shyamsunder Erramilli, Pritiraj Mohanty
Optics
Yudong Cui, Tianchang Lu, Yusheng Zhang et al. (+2 more)
This article presents a systematic review of theoretical and experimental findings for bound states of two and several dissipative
solitons in fiber
lasers. The theoretical basis underlying the formation and stabilization of
soliton molecules in the fibers, which is provided by the complex Ginzburg-Landau equations and bound states of such equations, is presented in necessary detail, which is followed by a detailed presentation of experimental findings, including very recent ones. In particular, included are the results for the multi-
soliton bound states in the fibers, as well as for the bound states in the temporal and frequency domains, single-component (scalar) and two-component (vector), two- and multi-
soliton modes, as well as for bound states of spatiotemporal dissipative
solitons in the
lasers based on multimode fibers.
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All authors Yudong Cui, Tianchang Lu, Yusheng Zhang, Dong Mao, Boris A. Malomed
Optics
Analysis of Electromagnetic Scattering from Semiconductor Nanostructures by Solving Coupled Volume Integral and Two-fluid Hydrodynamic Equations
Doolos Aibek Uulu, Meruyert Khamitova, Rui Chen et al. (+3 more)
Semiconductor-based plasmonic nanostructures support localized surface plasmon modes in the infrared region. Unlike metallic nanostructures, they support both free electrons and holes, requiring a two-fluid hydrodynamic Drude equation (HDE) to accurately capture spatial dispersion effects and low-frequency acoustic plasmon modes that cannot be described by single-fluid models. In this work, a volume integral equation (VIE)-based solver is proposed for the analysis of electromagnetic scattering from
semiconductor nanostructures. The proposed approach couples the VIE, formulated in terms of the electric flux density and the free-electron and hole polarization currents, with the two-fluid HDE. The coupled system is discretized using a tetrahedral mesh and solved efficiently using a two-level iterative solver. In contrast to finite-element-based methods, the proposed VIE-based approach does not require domain-wide meshing and inherently satisfies the radiation condition, thereby eliminating artificial absorbing boundaries. Numerical results for InSb-type
semiconductor nanostructures demonstrate the accuracy and efficiency of the proposed VIE-based solver and its ability to capture unique optical phenomena, such as acoustic plasmon resonances and the blueshift of localized surface plasmon resonances, that cannot be described by the single-fluid HDE or classical Drude-based models.
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All authors Doolos Aibek Uulu, Meruyert Khamitova, Rui Chen, Liang Chen, Ping Li, Hakan Bagci
Optics
Many-mode grating couplers by avoiding undesired couplings
Nazar Pyvovar, Hao Li, Zhaowei Dai et al. (+1 more)
To couple many independent modes from free space to on chip, the key challenge is not enhancing the many necessary coupling rates (scattering-
matrix elements) between targeted mode pairs. Instead, the key is to avoid additional cross-couplings to undesired modes, due to the presence of multiple simultaneously satisfied phase-matching conditions. With this principle, we identify scaling laws for the maximum number of high-efficiency multi-mode couplings that may be achievable for a given refractive index and design region, which are strongly supported by extensive numerical inverse-design experiments in 2D (one-dimensional coupler patterns, scattering in 2D). For such couplers, typical mode counts of 5–10 appear achievable. Three-dimensional couplers (patterned across two dimensions) can be markedly better, with tens of
Fourier components in a single-layer device offering the possibility of high-efficiency coupling of hundreds to thousands of modes in relatively compact form factors. Numerical simulations of such a device, without any parameter optimization, predict efficiencies on the order of 5% for 100 modes – a collective order-of-magnitude improvement over previous designs.
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All authors Nazar Pyvovar, Hao Li, Zhaowei Dai, Owen D. Miller
Physics and Society
Assessing the Role of Intersection Proximity in Pedestrian Crashes: Insights from Data Mining Approach
Ahmed Hossain and Xiaoduan Sun
Although intersections are the most complex parts of the roadway network, pedestrian crashes at non-intersection locations are disproportionately frequent, highlighting a serious traffic safety concern. This study investigates non-intersection crashes involving pedestrians using a crash database (2017-2021) collected from Louisiana State. As the risk of pedestrian crashes tends to vary with distance from the intersection, the research team utilized a unique framework "distance to intersection" to capture the differences in crash patterns at non-intersection locations. The study identified that around 50% of non-intersection pedestrian crashes occurred within 198 ft. of the intersection. In the next step, the collected 3,135 pedestrian crashes at non-intersection locations during the study period were subdivided into three zones: D1 zone designates crashes occurring within 150 ft. of an intersection (1,277 crashes), D2 zone designates crashes occurring within 151 ft. to 435 ft. of an intersection (1,060 crashes) and D3 zone designates crashes occurring at 435 ft. or higher from an intersection (798 crashes). To explore the complex interaction of multiple factors, an intuitive data mining technique, Association Rules Mining was used. A total of the top 60 interesting association rules (20 for each zone) were identified by the
algorithm (based on lift and support measures). In addition, a total of 124 rules were explored based on Lift Increase Criterion (LIC) measure. The findings of this research provide critical insights into pedestrian crash involvement at non-intersection locations and the variation in crash patterns according to the "distance to intersection". Based on the findings, some of the targeted problem-specific countermeasures are also recommended to address the crash patterns at non-intersection locations.
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Optics
Multimode grating couplers via foundry-compliant inverse design
Hao Li, Nazar Pyvovar, Zhaowei Dai et al. (+1 more)
We apply a systematic inverse design approach to discover foundry-compliant, multilayer grating couplers that can efficiently couple a number of independent waves from free space to on-chip propagating modes. For visible- and near-infrared couplers, we find that minimum feature sizes are by far the most important constraint to tailor the design
algorithms around. If, additionally, one forces the optimization to be robust to over- and under-etch errors, the resulting designs exhibit stable optimal efficiencies in the presence of other imperfections (critical dimension variations, overlay mismatch, and sidewall angle variation). The foundry-compliant designs exhibit moderate efficiency penalties as feature sizes increase, but no change to simple underlying scaling laws with respect to requisite numbers of layers and layer thicknesses. These results establish a practical, generalizable framework for high-efficiency multimode coupling within the constraints of modern
semiconductor foundries.
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All authors Hao Li, Nazar Pyvovar, Zhaowei Dai, Owen D. Miller
Optics · Cross-listed from cond-mat.mes-hall
Deep Strong light-matter Coupling in 3D Kane Fermions
Dmitriy Yavorskiy, David Hagenmuller, Noureddine Charrouj et al. (+5 more)
Deep strong light-matter coupling represents an extreme non-perturbative regime of
quantum electrodynamics, in which the interaction strength exceeds the bare frequencies of the uncoupled systems. The ground state features strong
quantum correlations between
photons and matter excitations, and new cavity-driven phase transitions are expected to occur. Whether a superradiant
quantum phase transition, marked by spontaneous dipole ordering and
photon condensation, is possible has remained a long-standing and controversial question. Such phenomena have been proposed to arise in exotic electronic systems hosting Dirac and Kane
fermions, owing to the formal absence of an $A^2$ term in their low-energy
Hamiltonian. Here we exploit the ultralow effective mass of Kane
fermions to realise Landau polaritons in a bulk mercury cadmium telluride layer coupled to a Fabry-Perot resonator. Using thermally tunable carrier density, we continuously tune the coupling from the weak to the deep-strong regime, achieving a record normalised coupling ratio exceeding 1.6 above room temperature. The measured polariton spectra are in excellent agreement with a rigorous, gauge-invariant microscopic theory. Despite the nonlinear Landau level structure of relativistic Kane
fermions, we show that a diamagnetic $A^2$ term naturally emerges and precludes a superradiant phase transition. These results resolve the long-standing controversy surrounding cavity
quantum electrodynamics of relativistic-like matter systems, extend deep-strong-coupling physics to Kane
fermions, and open new opportunities for polaritonic
semiconductor devices operating in extreme light-matter coupling regimes.
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All authors Dmitriy Yavorskiy, David Hagenmuller, Noureddine Charrouj, Yurii Ivonyak, Alexander Kazakov, Yanko Todorov, Wojciech Knap, Marcin Bialek
Physics and Society · Cross-listed from cs.CL
Ease of dependency distance minimization in star-like structures
Emília Garcia-Casademont and Ramon Ferrer-i-Cancho
The syntactic structure of a sentence can be represented as a tree where edges indicate syntactic dependencies between words. When that structure is a
star, it has been demonstrated that the head should be placed in the middle of the linear arrangement according to the principle of syntactic dependency distance minimization. However, hubs of
stars tend to be put at one of the ends, against that principle. Here we address two questions: (1) How difficult is it to minimize dependency distance? (2) Why anti dependency distance minimization effects have been found in
star structures but not in path structures? The ease of optimization is determined by the shape of the optimization landscape. It was demonstrated that the landscape of
star structures is quasiconvex (Ferrer-i-Cancho 2015,
Language Dynamics and Change). As for (1), here we show that it is indeed convex (a particular case of quasiconvexity) both for
star trees and quasistar trees and thus the distance-based optimization problem is simpler than previously believed. As for (2), we argue that (a) competing principles, rather than the difficulty of optimization, must be the actual reason for anti-dependency distance minimization effects and that (b) dependency distance minimization on
star-like structures is less rewarding compared to other structures.
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Physics and Society
Universal statistical laws governing culinary design
Ganesh Bagler, Gopal Krishna Tewari, Aditya Raj Yadav et al. (+5 more)
Cooking is a cultural expression of human creativity that transcends geography and time through the orchestration of ingredients and techniques, much like
languages do through words and syntax. Yet, beneath the apparent diversity of culinary traditions, whether recipes obey statistical laws comparable to those of other symbolic systems remains unknown. Here we analyze a large corpus of traditional recipes spanning global cuisines, annotated using a state-of-the-art named entity recognition
algorithm into ingredients, cooking techniques, utensils, and other culinary attributes. We find that ingredient usage exhibits Zipf-like rank-frequency scaling, that culinary diversity grows sublinearly with corpus size in accordance with Heaps' law, and that recipe complexity follows Menzerath-Altmann-type relations between the number and average information of constituent units. Consistent with observations in packaged foods, macronutrient concentrations across recipes also display a log-normal signature. Minimal generative models based on preferential reuse, constrained sampling, and incremental modification recapitulate these regularities, suggesting generic processes that shape recipe architecture across cultures. Together, these findings establish recipes as a compositional symbolic system in which complex structure emerges from simple, constrained generative processes.
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All authors Ganesh Bagler, Gopal Krishna Tewari, Aditya Raj Yadav, Akshat Singh, Pranay Bansal, Ujjval Dargar, Mansi Goel, Madhvi Kumari Sinha
Computational Physics · Cross-listed from cond-mat.mes-hall
Compressibility of micromagnetic solutions in tensor train format
Thierry Valet and Nicolas Vukadinovic
For three-dimensional (3D)
magnetic objects with linear size $L$ exceeding a few exchange lengths, the micromagnetic state exhibits pronounced informational sparsity: low-dimensional, high-gradient regions (e.g., domain walls) coexist with near-uniformly magnetized volumetric domains. Because standard micromagnetic simulation methods discretize the magnetization on near-uniform 3D grids with linear
cell size $a$, they cannot take advantage of this sparsity. The computational problem scales as $\sim L^3$ and $\sim (1/a)^3$. In this Letter, we establish that direct tensor-train (TT) representations overcome these poor scalings by exploiting the spatial sparsity optimally, while preserving accuracy in a controlled way. Focusing on representative flux-closure configurations in soft-
magnetic rectangular prisms, in the near-micrometer regime, we demonstrate that the parameter count of TT-compressed micromagnetic data scales approximately as $L^{1.8}$ and $(1/a)^{1.2}$. Hence the relative advantage over dense discretizations rapidly grows with the problem size and refinement level. These first results provide a strong motivation for future developments of micromagnetic solvers in TT format which could transcend the limitations of traditional simulators, with far reaching potential impacts on fundamental research and technology development.
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Physics and Society · Cross-listed from cond-mat.dis-nn
The Synergistic Route to Stretched Criticality
Lorenzo Lucarini, Sandro Meloni and Pablo Villegas
Griffiths phases are typically associated with quenched disorder, while frustration gives rise to multistability and
spin-glass behavior. Whether extended criticality can arise in other contexts remains an open question. Here, we show that synergistic interactions provide a distinct route to non-conventional critical phenomena. By combining spreading mechanisms that reinforce activity through complementary pathways, we uncover a broad distribution of relaxation rates, leading to Griffiths-like slow dynamics and extended criticality. We demonstrate that this mechanism is robust across networks and emerges both in systems with explicit higher-order interactions and in purely pairwise systems with nonlinear dynamical rules.
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Atomic Physics
Spatially Resolved Temperature Measurement Using Rydberg Doppler Broadening Thermometry
K. N. Trivedi, M. Carminati, Èlia Solé Cardona et al. (+4 more)
We demonstrate a technique for spatially resolved temperature measurement utilizing Rydberg Doppler broadening thermometry. This method employs two focused
laser beams arranged perpendicularly to excite
laser-cooled atoms from the ground state to a Rydberg state via two
photon absorption process. Temperature is obtained through the Doppler broadening of the spectral line. The perpendicular configuration allows for selective probing of a specific position within the atomic cloud, enabling localized temperature measurement. This technique, in principle, offers a temperature resolution on the order of \SI{}{\nano\kelvin}, attributed to the exceptionally narrow natural linewidth of the involved rubidium Rydberg transition line. Furthermore, the setup enables the measurement of position-velocity correlations within the cold atom ensemble. The velocity information is extracted through the Doppler shift, whereas the spatial information is inferred from the arrival time of ions detected by a channel electron multiplier detector. We use our method to measure the local temperature in a magneto-optical trap.
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All authors K. N. Trivedi, M. Carminati, Èlia Solé Cardona, T. Bonaccorsi, R. Donofrio, B. Bégoc, O. Morsch
Fluid Dynamics
Mixture-aware closure of the N-phase Navier–Stokes–Cahn–Hilliard mixture model
M.F.P. ten Eikelder and A. Brunk
Diffuse-interface (phase-field) models are widely used to describe multiphase mixtures and their interfacial dynamics. In multiphase settings, however, the constitutive closure should remain meaningful across different representations of the same mixture. Existing N-phase phase-field constructions commonly enforce reduction only when a phase is absent (restriction to a face of the Gibbs simplex), but do not address the natural requirement that physically identical phases can be merged without changing the governing equations. This requires characterizing thermodynamically admissible, mixture-aware constitutive closures that are consistent with merging identical phases at the PDE level. Here, we show that, under a small set of structural axioms, PDE-level reduction consistency uniquely fixes the admissible free-energy structure to an ideal-mixing contribution to an ideal-mixing contribution, a symmetric mean-field interaction term, and a constant-coefficient quadratic gradient penalty. yielding a thermodynamic closure that includes Maxwell–Stefan-type mobilities as a special case. The same requirement constrains the Onsager mobility
matrix to a pairwise-exchange form with bilinear degeneracy in the volume fractions, yielding a thermodynamic closure that includes Maxwell–Stefan-type mobilities as a special case. These results provide a consistent closure for N-phase Navier–Stokes–Cahn–Hilliard mixture models and, in the bulk-only setting, for multiphase Maxwell–Stefan
diffusion systems. Numerical experiments confirm the predicted mixture-aware reduction properties and illustrate the capabilities of the N-phase Navier–Stokes–Cahn–Hilliard framework in representative multiphase-flow computations.
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Biological Physics · Cross-listed from cond-mat.soft
Propelling catalytic structures using active biomolecular condensates
Benjamin Sorkin and Ned S. Wingreen
Living systems routinely consume energy to achieve motility, often using intricate biomolecular machinery. In this work, we demonstrate that active biomolecular condensates enable the self-propulsion of micron-sized objects in otherwise homogeneous, isotropic, and autonomous environments. Our proposed minimal mechanism consists of phase-separating
proteins, the enzymes that passivate them, and complementary enzymes isotropically anchored to a spherical-colloid surface which reactivate the
proteins. This passivation-activation cycle gives rise to a
symmetry breaking wherein a single biocondensate is stabilized near the colloid surface, which in turn exerts a repulsive force on the colloid. We numerically demonstrate that this mechanism can propel micron-sized colloids at speeds of up to a hundred microns per second. This propulsion mode is strongly resistant to Brownian fluctuations and external forces. Propulsion mechanisms based on biomolecular condensates may thus offer a complementary, motor-free route to biological transport.
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Atomic Physics
International Optical Clock Comparison Using the European Optical Fiber Network
Marco Pizzocaro, Clara Zyskind, Anne Amy-Klein et al. (+41 more)
Optical clocks have achieved remarkable estimated fractional frequency uncertainties reaching the $10^{-18}$ level and below, enabling applications in fundamental physics, general relativity, and geodesy. However, the challenge of verifying the international consistency of optical clocks remains critical as efforts intensify toward redefining the SI second based on an optical transition or transitions. We report on a two-month international clock comparison campaign involving seven optical clocks in four national metrology institutes (INRIM, LNE-OP, NPL, and PTB) connected via the optical fiber network established in Europe. The campaign resulted in optical frequency ratios with uncertainties ranging from $7.7\times10^{-18}$ to $6.1\times10^{-17}$. Among the results, the $^{171}$Yb$^+$(E3) clocks at NPL and PTB demonstrated agreement within an uncertainty of $7.7\times10^{-18}$, marking the first international verification of two independently developed optical clocks below one part in $10^{17}$. The operation of the $^{199}$Hg clock at LNE-OP (formerly LNE-SYRTE) resulted in frequency ratios with improved uncertainties with $^{171}$Yb$^+$(E3), $^{171}$Yb, and $^{87}$Sr optical clocks. These results provide input for the redefinition of the second and underscore how fiber-linked clock networks can advance metrology and scientific applications.
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All authors Marco Pizzocaro, Clara Zyskind, Anne Amy-Klein, Erik Benkler, Sebastien Bize, Davide Calonico, Etienne Cantin, Christian Chardonnet, Cecilia Clivati, Stefano Condio, E. Anne Curtis, Simone Donadello, Sören Dörscher, Chen-Hao Feng, Melina Filzinger, Jacques-Olivier Gaudron, Rachel M. Godun, Irene Goti, Ian R. Hill, Wei Huang, Nils Huntemann, Matthew Johnson, Joshua Klose, Jochen Kronjäger, Alexander Kuhl, Rodolphe Le Targat, Filippo Levi, Burghard Lipphardt, Christian Lisdat, Jerome Lodewyck, Olivier Lopez, Helen S. Margolis, Maxime Mazouth-Laurol, Alberto Mura, Benjamin Pointard, Paul-Eric Pottie, Matias Risaro, Billy I. Robertson, Marco Schioppo, Kilian Stahl, Martin Steinel, Alexandra Tofful, Mads Tønnes, Jacob Tunes