Physics and Society
Community detection in subject-subject networks from psychometrics data
Arianna Armanetti, Luca Cecchetti, Eiko Fried et al. (+2 more)
Identifying subgroups of respondents in psychometric data is traditionally addressed with Latent Class Analysis, which requires the number of classes to be specified a priori and can perform poorly when strong inter-item correlations violate local independence assumptions. We propose a network-theoretic alternative based on community detection in subject-subject similarity networks. To suppress the systematic artifacts induced by the factor structure of the items, the similarity is computed in a low-dimensional factor-score space and the null model for modularity maximisation is obtained by removing the leading (global) mode of the similarity
matrix, rather than via the standard Newman–Girvan model. The significance of a detected partition is then assessed against a column-wise resampling null through four complementary observables: the modularity, the differential
entropy of the eigenvector point cloud at two neighbourhood scales, and the overlap of the within- and between-community similarity histograms. On a synthetic
benchmark with controlled mixture signal, all four metrics correctly identify the homogeneous case as null-compatible – including the demanding regime of a
dataset dominated by a single factor – and exhibit a graded departure from the null as the cluster separation grows. Applied to 14 widely used psychometric scales, the pipeline isolates a small group of
datasets supporting a genuine and directly interpretable modular structure, while the remaining scales fall either in a mixed-signal regime or in one compatible with a single homogeneous community. The significance analysis is independent of the specific community-detection
algorithm and provides an operational way to test for modular subject-level structure in questionnaire data.
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All authors Arianna Armanetti, Luca Cecchetti, Eiko Fried, Diego Garlaschelli, Miguel Ibáñez-Berganza
Data Analysis and Statistics
Inverse generalised spin models of answers to questionnaires
Arianna Armanetti, Luca Cecchetti, Paolo Sarti et al. (+2 more)
Network psychometrics conceptualises psychological constructs as emergent properties of systems of interacting items. Energy-based probabilistic models have gained popularity as models of these interactions, but their psychometric application has so far been limited to binary responses, bilinear interactions, and approximated inference methods. To fill these gaps, we here infer and analyse three generalized-
spin models of ordinal questionnaire data: the Ising, Blume-Capel (BC), and Blume-Emery-Griffiths (BEG) models. These are maximum-
entropy models that accommodate ordinal responses on Likert-type scales with an arbitrary number of options, allowing for single-site anisotropy (BC, BEG) and bi-quadratic item interactions (BEG). We prove the concavity of the maximum likelihood estimation of their parameters, as well as the gauge invariance of the Ising and BC models. We introduce a
stochastic gradient ascent
algorithm for maximum likelihood inference, and apply this procedure to eleven psychometric and sociological questionnaire
datasets. Evaluating the predictive ability of the inferred models reveals that the BEG model systematically outperforms Factor Analysis and the other
spin models in capturing the distributions of factors and distances of subject answers to the mean, across all
datasets. By leveraging a competitive interplay between the quadratic and bi-quadratic energy terms, the BEG model uniquely captures individual average-extremist response styles, alongside standard latent factor positioning. Moreover, only the
spin models can account for the non-concavity and multi-modality of factor histograms in the most polarizing questionnaires. Finally, the analysis reveals other highly non-linear traits of ordinal data—such as the fat-tailed distribution of Mahalanobis distances to the mean—that escape satisfactory description by both factor and
spin models.
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All authors Arianna Armanetti, Luca Cecchetti, Paolo Sarti, Diego Garlaschelli, Miguel Ibáñez-Berganza
History and Philosophy of Physics
The Tychonic system, an implausible theory
Gabriele Vanin
Several scholars have accorded the Tychonic System a prominent place, considering it a credible alternative to the Ptolemaic and Copernican systems. In recent years, there have even been some enthusiastic contributions in support of Brahe, which have sought to show how his solutions were the most suitable for providing scientifics support to the new observations that were accumulating between the late 16th century and the mid-17th century. In this work, after analyzing these contributions, I proceed to demonstrate that the Tychonic system had so many critical points, many of which have not been adequately noted by historical criticism, that it did not deserve all the
attention it received, neither at the time of its publication, nor in Galileo's time, nor in subsequent periods, because it never constituted a truly credible alternative, and that its reputation as the "third system of the world" is entirely undeserved.
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Applied Physics
Decoupling heat and electricity: A thermal invisible gateway
Jiahao Li, Fei Sun, Yichao Liu et al. (+4 more)
The Wiedemann-Franz law couples electrical and thermal conductivity, making high electrical conduction with low thermal conduction a major challenge. To overcome this, we designed an active thermal metasurface (ATMS) - based thermal invisible gateway that decouples thermal and electrical paths. Built on a copper substrate with a dumbbell-shaped bridge, the structure suppresses heat flow via directional compensation while allowing unimpeded electrical conduction. Room-temperature experiments show an effective thermal conductivity below 10^-3 W m^-1 K^-1 (near zero, air-like insulation) and an electrical conductivity up to 2.8x10^7 S m^-1 (metal-level). Unlike conventional material-modification approaches, our work uses macroscopic structural design to break the intrinsic coupling, offering a promising solution for applications like on-chip interconnects and wearable electronics.
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All authors Jiahao Li, Fei Sun, Yichao Liu, Yawen Qi, Qin Liao, Jianpu Yang, Zhiru Xie
Chemical Physics · Cross-listed from cs.LG
A Systematic Evaluation of Molecular Mixture Behavior Prediction
Roel J. Leenhouts, Nathan K. Morgan, William Green et al. (+2 more)
Machine learning for molecular property prediction has focused largely on pure compounds, even though many practical applications depend on mixtures with intermolecular interactions. Recent work has expanded the availability of mixture
datasets, but evaluation still focuses mainly on absolute accuracy. However, absolute errors in mixtures conflate pure-component contributions with deviations from ideal mixing. We propose an evaluation framework that decomposes mixture-property error into pure-compound and interaction (non-ideal) components. The framework combines leakage-aware split protocols, ideal-mixture baselines, and excess-property metrics. To support reproducible benchmarking, we curate seven matched pure and mixture physicochemical property
datasets. Across multiple mixture-property tasks and model families, we find that strong absolute accuracy can mask poor recovery of non-ideal mixture behavior, and that performance drops substantially under strict molecule splits. These results identify transfer to unseen molecules as a central challenge in molecular mixture machine learning and motivate evaluation beyond absolute accuracy alone.
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All authors Roel J. Leenhouts, Nathan K. Morgan, William Green, Jan G. Rittig, Florence H. Vermeire
History and Philosophy of Physics
That Damned Equation. Rigour, Credit Attribution, and the Wheeler-DeWitt Equation 1962-1967
Alexander S. Blum, Dean Rickles and Karim Thébault
The notion of rigour relevant to the practice of physics is an endogenous one. Theoretical physics has its own internal norms about mathematical practice and notions of legitimate derivations or formal objects. These norms are often implicit, local, and change in substantial ways over time. Moreover, norms of rigour in theoretical physics, at least in the mid-twentieth century, are primarily focused on the goal of removing barriers for concrete calculation and clear conceptualisation. Rather than pursuit of rigour for its own sake, or to achieve some `higher' standard of truth, theoretical physicists seek to `rigorise' initial, semi-formal constructions in order to render formally well-defined models with which they can make concrete contact with the world, through calculations of quantities of interest. In what follows we will support this thesis based upon a detailed historical case study of the development of and attribution of credit for the Wheeler-DeWitt equation in the period 1962-67. Drawing upon archival material and the published record we develop and defend the explanatory hypothesis that it was the rigorisation of the equation via the expression for the inner product that was the crucial step in the work of Wheeler and DeWitt rather than the statement of the equation itself.
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Computational Physics
WF-Bench: A Benchmark for Neural Network WaveFunction Expressivity and Scaling Laws
Lixing Zhang, Guijing Duan and Di Luo
We present a comprehensive benchmarking
dataset and empirical scaling law analysis for neural network wavefunctions by matching them to a wide spectrum of famous many body target wavefunctions. The
dataset, WF-Bench, spans multiple distinct regimes of strongly correlated
quantum matter, including topological states, Wigner
crystals, and superconducting wavefunctions, providing a diverse and challenging test bed for neural network wavefunction expressivity. We introduce a systematic and reproducible benchmarking protocol for target wavefunction matching, enabling consistent performance evaluation across different neural network wavefunction architectures. By using wavefunction fidelity as the uniform metric, we discover empirical scaling laws that characterize how representability depends on system size and key model parameters, including number of determinant and model depth. By applying our
benchmark protocol on Psiformer and Ferminet, we show that WF-Bench establishes a unified
dataset driven framework for evaluating and comparing neural network wavefunctions and for guiding the design of future architectures.
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Chemical Physics · Cross-listed from cs.LG
MōLe-{\Lambda}: Learning the Coupled-Cluster Response State for Energies, Gradients, and Properties
Andreas Burger, Luca Thiede, Abdulrahman Aldossary et al. (+4 more)
Coupled-cluster (CC) theory is often considered the gold standard of
quantum chemistry, but its high computational cost limits routine access to accurate energies, forces and response properties. While the right-hand $T$-amplitudes determine the correlated wavefunction, many practically important observables additionally require the left-hand $\Lambda$-amplitudes. We introduce MōLe-$\Lambda$, an extension of Molecular Orbital Learning (MōLe) that predicts the full ground-state coupled-cluster singles and doubles (CCSD) response state by jointly learning right-hand amplitudes $(T_1,T_2)$ and left-hand amplitudes $(\Lambda_1,\Lambda_2)$ from localized Hartree–Fock molecular orbitals. Architecturally, MōLe-$\Lambda$ extends MōLe with $\Lambda_1$ and $\Lambda_2$ readouts that mirror the
symmetry constraints of the $T_1$ and $T_2$ heads, while preserving the original equivariant orbital encoder, odd sign-equivariant decoding, locality and size-extensivity. The resulting model yields accurate CC-quality energies and forces, while simultaneously recovering dipoles, quadrupoles, polarizabilities, the electron density, and 2-electron observables such as the pair density. We show that MōLe-$\Lambda$ further extends the speed advantage of MōLe over full CCSD while substantially expanding the accessible properties, providing a route to wavefunction-level surrogate models for correlated
quantum chemistry.
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All authors Andreas Burger, Luca Thiede, Abdulrahman Aldossary, Jorge A. Campos-Gonzalez-Angulo, Alex Zook, Jérôme Florian Gonthier, Alán Aspuru-Guzik
Optics · Cross-listed from quant-ph
Engineering recoil heating in coherent-scattering levitated optomechanics
Maksim Lednev, Uroš Delić, Johannes Feist et al. (+1 more)
Recoil heating from
photon scattering is a fundamental source of decoherence in optical trapping, severely limiting the preparation of nonclassical motional states. In cavity setups in the coherent scattering configuration, a predictive theory of
recoil heating rate is missing, as usual perturbative approaches fail in the presence of sharp optical resonances. Hence, current works assume that the
recoil heating rate is approximately equal to its free-space value. Here we show that this is not the case, as the electromagnetic environment can strongly modify
recoil heating rate by the Purcell effect. Specifically, we predict that this rate can be significantly suppressed in state-of-the-art microcavities, for both center-of-mass and librational motion. To establish these results, we develop a general theoretical framework based on macroscopic
quantum electrodynamics and on the few-mode quantization approach developed in nanophotonics. Our method applies to particles trapped in the presence of arbitrary electromagnetic structures, thus providing a route to engineering motional decoherence in levitated optomechanics by photonic structure design.
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All authors Maksim Lednev, Uroš Delić, Johannes Feist, Carlos Gonzalez-Ballestero
Instrumentation and Detectors
Effect of increased DCR on the detection of minimum-ionizing particles with SiPMs
Katjana Neumann, Massimiliano Antonello, Lukas Brinkmann et al. (+2 more)
Radiation damage to a Silicon Photomultiplier (SiPM), as it occurs during the lifetime of the planned CMS high-granularity calorimeter detector, increases the dark current and degrades the signal-to-noise separation for minimum-ionizing particles (MIPs) and their detection efficiency. To investigate these effects, a plastic scintillator tile air-coupled to a SiPM is used to detect MIPs from a 90Sr source, in a single-channel design similar to the tiles of the CMS high-granularity calorimeter upgrade. We compared the SiPM responses after actual radiation exposure with responses simulated in the laboratory by increasing the dark-count rate (DCR) through optical illumination with an LED light source. This optical method induces no structural damage or deep defects, thus isolating the effect of increased dark-count rate. Our results show that both radiation-induced damage and LED-induced dark-count rate increases lead to similar reductions in the MIP signal and the signal-to-noise ratio. This indicates that the primary factor for the performance degradation is the elevated dark-count rate itself, rather than additional defects in the silicon. The results demonstrate that the key effects of radiation damage on SiPMs can be effectively replicated using controlled optical illumination, providing a practical and easily accessible approach for evaluating and optimizing SiPM performance under radiation-like conditions in the laboratory.
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All authors Katjana Neumann, Massimiliano Antonello, Lukas Brinkmann, Erika Garutti, Jörn Schwandt
Atmospheric and Oceanic Physics · Cross-listed from math.NA
An IMEX-DG solver with non-conforming mesh refinement for atmospheric dynamics with rotation
Letizia Bottani, Tommaso Benacchio, Giuseppe Orlando et al. (+2 more)
We present a high-order implicit-explicit discontinuous Galerkin (IMEX-DG) solver for the compressible Euler equations to account for rotational effects within a fully compressible atmospheric framework. Time integration follows a second-order additive Runge-Kutta scheme, treating stiff acoustic modes implicitly and advective terms explicitly. The solver is built on the deal.II finite element library, combining
matrix-free operator evaluation, adaptive non-conforming meshes capabilities, and distributed-
memory parallelism. Two alternative treatments of the rotational and gravitational source terms within the solution strategy, based on nonlinear fixed-point iterations, are introduced and compared in terms of accuracy, robustness, and computational efficiency. A discrete analysis of the rotational operator is also carried out in order to derive a formulation suitable for efficient
matrix-free implementation and to avoid inconsistent naive discretisations. The proposed formulation is validated through convergence studies on rotating inertia-
gravity wave
benchmarks and further assessed in fully three-dimensional simulations of stratified flow over orography on both uniform and adaptive meshes. The numerical results show that the rotating IMEX-DG framework has the expected accuracy and stability properties while correctly capturing the asymmetry and wave structures induced by rotation in large-scale atmospheric flows.
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All authors Letizia Bottani, Tommaso Benacchio, Giuseppe Orlando, Luca Bonaventura, Allan Peter Engsig-Karup
Optics
Giant Photon Superbunching from Weak Nonlinearity
You Wang, Xu Zheng, Timothy C. H. Liew et al. (+1 more)
Photon superbunching, which occurs when the second-order correlation satisfies $g^{(2)}> 2$, is typically associated with strong optical nonlinearities or collective multi-
photon emission processes. We predict that extreme superbunching can also arise in systems of weakly-nonlinear photonic cavities, via the creation of a squeezed
vacuum through interference engineering by fine-tuning inter-cavity couplings and drive parameters. We present numerical calculations indicating that a system of four photonic resonators containing representative Kerr media can achieve $g^{(2)}(0) = 135$ with a $80\,\text{kHz}$ emission rate. Unlike earlier superbunching schemes, this mechanism is highly compatible with integrated photonic platforms constructed using conventional optical media.
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All authors You Wang, Xu Zheng, Timothy C. H. Liew, Y. D. Chong
Applied Physics · Cross-listed from cond-mat.mes-hall
Revealing quantum metric multipoles in magnetic topological insulator MnBi2Te4
Lars Sjöström, Prasanna Rout, Shahid Sattar et al. (+9 more)
Nonlinear electronic transport has emerged as a powerful probe of the
quantum geometry in topological
quantum materials, where the band
topology and broken
symmetries facilitate power law current voltage responses beyond Ohms law. While nonlinear transport of the second and third orders has been studied in several
quantum materials, higher-order transport has so far mainly remained experimentally inaccessible, leaving more detailed features of the
quantum geometry unexplored. Here, we observe higher order nonlinear electronic transport up to the seventh harmonic order in multilayer
magnetic topological
insulator MnBi2Te4. We find an even-odd behavior where the odd order nonlinear transport components dominate while the even-order ones are suppressed. Temperature and
magnetic field dependent measurements show a strong correlation between the nonlinear transport and the
magnetic phases of MnBi2Te4. Through scaling analysis and theoretical calculations,
quantum metric multipoles and nonlinear Drude conductivities are identified as the microscopic origins of the nonlinear transport.
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All authors Lars Sjöström, Prasanna Rout, Shahid Sattar, Alexander Tyner, Maurice E. Bal, Ankit Khola, Elias Rasmussen, Khadiza Ali, Arumugum Thamizhavel, Uli Zeitler, Carlo M. Canali, Saroj P. Dash
Medical Physics
CT Imaging with Helium and Carbon Ions for Hadron Therapy
Zsófia Jólesz, Gábor Bíró, Gábor Papp et al. (+1 more)
Objective: To perform a comprehensive comparative analysis of
proton, helium-ion, and carbon-ion computed
tomography (CT) as direct imaging modalities for
hadron therapy treatment planning, focusing on Relative Stopping Power (RSP) reconstruction accuracy and patient radiation dose. Approach: High-fidelity Monte Carlo simulations were conducted using the GATE/Geant4 platform to model a standard CTP404 phantom. RSP maps were reconstructed using an iterative Richardson-Lucy deconvolution
algorithm. Imaging performance was evaluated by comparing reconstructed RSP values against ground truth data for various tissue-equivalent inserts, while integral doses were estimated for a human head geometry. Main results: All investigated particle modalities demonstrated a significant dose reduction compared to conventional X-ray CT protocols (which are approximately 40 mGy). The estimated imaging doses were 1.6 mGy for
protons, 3.9 mGy for helium ions, and 22.7 mGy for carbon ions. In terms of accuracy, carbon-ion imaging achieved the highest fidelity for soft-tissue materials (mean absolute error <0.5%). Helium ions offered a balanced performance with sub-1% errors for most materials and a dose burden significantly lower than carbon ions.
Protons exhibited the widest range of RSP deviations (-1.8% to +3.1%). Significance: Direct particle imaging eliminates the systematic uncertainties inherent in
photon-to-
hadron conversion. While carbon ions provide superior RSP reconstruction precision essential for complex treatment plans in heterogeneous anatomy, helium and
proton imaging offer exceptional dose sparing, making them particularly advantageous for pediatric patients and frequent adaptive replanning scenarios.
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All authors Zsófia Jólesz, Gábor Bíró, Gábor Papp, Gergely Gábor Barnaföldi
Atmospheric and Oceanic Physics
Retrieval of Ocean Surface Currents and Vertical Shear from HF Radar Observations
G. Hasson, S. Støle-Hentschel, T. Vrećica et al. (+2 more)
The upper few meters of the ocean play a key role in air-sea exchanges of momentum and energy. Two important properties of this layer are the vertical shear of current velocity and the surface velocity. Vertical shear reflects momentum transfer, while the surface current velocity is essential for modeling transport processes such as pollutant dispersion. Direct measurements are challenging, and methods that provide continuous, real-time, and spatially extensive observations are highly desirable. This proof-of-concept study presents a new approach for estimating the radial component of surface velocity and the vertical shear of sea surface currents using a single-frequency high-frequency (HF) radar. The method is based on estimating the two first-order Bragg peaks in the backscattered radar spectrum which exhibit asymmetric frequency shifts in the presence of shear. The integral shear is retrieved from the frequency difference between the two peaks, while a new spectral processing technique enables correction of the surface velocity estimate for the effect of shear. The approach was tested using data from a WERA HF radar deployed off Ashkelon (Israel), and validated against simultaneous acoustic Doppler current profiler (ADCP) measurements at lower depths. The retrieved shear magnitudes and surface velocities show consistent trends with ADCP and wind observations, indicating that the method is applicable under strong-wind conditions for HF radar systems providing high-quality Doppler spectra.
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All authors G. Hasson, S. Støle-Hentschel, T. Vrećica, V. Shrira, Y. Toledo
Accelerator Physics
Energy-saving metric of the isas project (innovate for sustainable accelerating systems)
M. Baylac, F. Bouly, J. Branlard et al. (+11 more)
This document presents the energy-saving metric of the project Innovate for Sustainable Accelerating Systems (iSAS), funded by the EU under its program HORIZON-INFRA-2023-TECH-01 via grant agreement n{\deg}101131435 (milestone 9.5)
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All authors M. Baylac, F. Bouly, J. Branlard, K. Canderan, J. D Hondt, P. Duschene, Y. Gomez-Martinez, J. Knobloch, A. Neumann, V. Parma, C. Pira, H. Saugnac, C. Schmidt, A. Stocchi
Atomic Physics
Isotope shifts and hyperfine splitting of the ${}^{1}S_{0}\rightarrow{}^{3}P_{1}$ transition in zinc
Felix Waldherr, Lukas Möller and Simon Stellmer
We report
laser-induced-fluorescence spectroscopy of the ${}^1S_0 \rightarrow {}^3P_1$ intercombination transition in neutral zinc at $307.6~\mathrm{nm}$. Isotope shifts are measured for all stable isotopes with kHz-level precision, improving previous data by about two orders of magnitude. For $^{67}\mathrm{Zn}$, we resolve the excited-state hyperfine structure and determine $\delta\nu^{67,64}_{\rm COG}=1085.933(7)~\mathrm{MHz}$, $A=608.922(3)~\mathrm{MHz}$, and $B=-18.995(10)~\mathrm{MHz}$. A King plot comparison with the ${}^1S_0 \rightarrow {}^1P_1$ 214-nm transition results in field- and mass-shift parameters of $F_{307.6,214}=1.17(5)$ and $K_{307.6,214}=-153(60)~\mathrm{GHz\ u}$. These results provide the spectroscopic basis for narrow-line cooling and precision measurements based on zinc, including the development of an optical clock.
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Optics
STEPIC: High-Speed Imaging via Spatio-Temporal Encoding in Photonic Integrated Circuits
Andrea Ciceri, Giacomo Corrielli, Giulia Bertolini et al. (+15 more)
High-speed imaging of
cells in flow is essential for probing cellular heterogeneity in large populations. Existing imaging approaches based on single-pixel detection and spatio-temporal encoding provide exceptional speed, but typically rely on bulky free-space optics, long dispersive elements, and are prone to
alignment instabilities. Here, we introduce STEPIC Microscopy, the first fully integrated on-chip system for high-speed imaging via spatio-temporal encoding in photonic integrated
circuits. Our platform leverages waveguides, splitters, fiber delay-lines, and 3D optical remappers to encode spatial information into the temporal domain, enabling robust image reconstruction of
cells flowing through microchannels. The monolithic architecture provides a compact and robust platform for high-throughput bioimaging, enabling scalable and practical implementations of ultrafast imaging systems.
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All authors Andrea Ciceri, Giacomo Corrielli, Giulia Bertolini, Cinzia De Marco, Vera Cappelletti, Serena Di Cosimo, Yunjie Deng, Yuqi Zhou, Martina Russo, Hiroshi Kanno, Kelvin Lee, Tianben Ding, Andrea Bassi, Roberto Osellame, Francesca Bragheri, Keisuke Goda, Nadia Brancati, Petra Paiè
Instrumentation and Detectors · Cross-listed from cond-mat.mes-hall
Nanoparticle manipulation with a carbon fiber tip in an electron microscope for $\mu$-SQUID magnetometry
Umesh Chandra Thuwal, Sumanta Maity, Clemens B. Winkelmann et al. (+2 more)
We report a carbon-fiber-tip based nanomanipulation system integrated into a scanning electron microscope for individual nanoparticle (NP) manipulation on a surface. Electrochemically etched amorphous carbon fiber tips with excellent mechanical
rigidity and sub-100 nm apex radii effectively reduce the van der Waals adhesion and enable reliable positioning of about 100 nm size NPs with about 100 nm precision. This system combines a piezoelectric bimorph for vertical tip motion, a four-quadrant piezo-tube for two-dimensional fine tip control and a two-dimensional piezoelectric walker for coarse lateral translation. Using this setup, we successfully position single Fe$_3$O$_4$
magnetic NPs on micron sized superconducting
quantum interference devices for optimal
magnetic coupling between them and probe a NP's magnetism.
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All authors Umesh Chandra Thuwal, Sumanta Maity, Clemens B. Winkelmann, Hervé Courtois, Anjan Kumar Gupta
Optics
Ultrahigh-Q All-Metallic Metasurfaces with Robust Near-Perfect Absorption
Hanlei Xu, Han Qi, Chaoying Shi et al. (+5 more)
High quality-factor (Q) resonant metasurfaces have attracted significant
attention due to their potential applications in cutting-edge fields of optics. However, limited by intrinsic dissipation losses, achieving both an extremely high Q factor and perfect absorption for strong light-matter interaction control in plasmonic metasurface is still highly challenging. Here, we demonstrate a plasmonic metasurface composed of symmetric double-pillars (SDPs) on a gold film, in which the flexibly tuned
geometric space enables precise control over the nonlocality of dark-mode Fabry-Perot bound states in the continuum (FP-BIC) and its coupling with Rayleigh anomaly (RA)-associated
lattice resonance. Based on the coupling control between these two modes, the radiative and dissipative losses are well balanced, resulting in a measured Q factor of 2180 (theoretical 2800) and absorption nearly 99%. Notably, the near-perfect absorption response is maintained over broad
geometric parameter windows of SDPs (height h=70-120nm, radius r=210-280nm), while the resonance retains a consistently high Q factor throughout these ranges. This hybrid coupling strategy establishes a general framework for designing high-Q, near-critical coupling plasmonic devices for ultrasensitive sensing, narrowband filtering, and active photonics.
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All authors Hanlei Xu, Han Qi, Chaoying Shi, Hong Zhang, Jun Wang, Ziming Meng, Guoliang Deng, Hao Zhou
Optics
Quantum optics of chiral and antichiral waveguide arrays
Peng Wang, Erik Hiltunen and John C Schotland
We study single-
photon scattering by atoms in arrays of one-way waveguides. We investigate both
chiral and antichiral arrays, where the one-way waveguides are aligned in the same and opposite directions, respectively. In the
chiral array, reciprocity is broken: one of the (spatial) dimensions is time-like, resulting in a light-cone feature of the scattered fields. In contrast, the antichiral array preserves reciprocity and exhibit scattering behavior typical of wave systems. In analogy with classical physical optics, we exmaine the geometrical optics, diffraction, and scattering regimes in the waveguide arrays. We illustrate our results using numerical simulations.
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Atomic Physics
Lingering Sweetness of Ethanol Clusters: Sensory Discovery and Objective Discrimination by Impedance-Based Electronic Tongue
Jiaxin Peng, Chaoyu Zhao, Xinyue Jiang et al. (+1 more)
Ethanol is conventionally perceived only as a pungent tastant, while the potential sweet properties of ethanol clusters have remained unrecognized. Here we show that ethanol tetramers exhibit a unique time dependent lingering sweetness, distinct from the immediate upupfront sweetness of conventional sweeteners. To objectively verify this phenomenon, we developed an impedance based bionic electronic tongue that monitors changes at a lipid
polymer membrane interface. Sensory evaluation revealed increasing ethanol cluster content from 4.83% to 29.53% prolonged sweetness duration from 10s to 25s, whereas sweetness intensity remained low to moderate (1.0-1.7 on a 10 point scale). Using this electronic tongue, we achieved objective discrimination between upfront and lingering sweetness,full band phase angle scanning identified optimal frequencies of 0.933Hz (t=0.171s) for xylitol (fast binding and dissociation) and 0.03Hz (t=5.305s) for ethanol clusters (slow binding and dissociation). Phase angle responses correlated strongly with sensory sweetness duration. In natural aged Chinese Baijiu (1-20 years), low frequency phase angle signals positively correlated with sensory lingering sweetness scores, confirming that ethanol cluster accumulation during aging underpins the sweetness of Baijiu. This work expands the classic AH-B sweetness theory from single molecules to supramolecular clusters and provides an analytical platform for probing the temporal dimension of
flavor perception.
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All authors Jiaxin Peng, Chaoyu Zhao, Xinyue Jiang, Yuqun Xie
Optics · Cross-listed from quant-ph
Near surface donor-acceptor pairs in hydrogenated homoepitaxial diamond nanolayers
A. M. Romshin, A.P. Bolshakov, A.A. Zhivopistsev et al. (+5 more)
Hydrogen-terminated diamond is known for its p-type surface conductivity, which arises from a near-surface hole accumulation layer induced by adsorbed acceptor species. Here, we demonstrate that these surface acceptors also form optically active donor-acceptor pairs (DAP) with substitutional nitrogen donors in diamond. The insertion of a nominally undoped CVD interlayer between a nitrogen-rich HPHT substrate and a hydrogen-terminated surface enables the precise tuning of the donor-acceptor separation with nanometer precision. Radiative DAP recombination appears as bright, spectrally narrow lines whose intensity, energy, and decay dynamics depend systematically on interlayer thickness. Individual lines show single-
photon statistics, while ensembles exhibit strong polarization anisotropy reflecting the planar donor-acceptor geometry. These findings reveal an optical counterpart of hydrogen-induced surface transfer doping in diamond and establish a surface-defined, nanometer-tunable platform for engineering DAP-based
quantum emitters.
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All authors A. M. Romshin, A.P. Bolshakov, A.A. Zhivopistsev, A. V. Gritsienko, O. S. Kudryavtsev, P. A. Pivovarov, V. G. Ralchenko, I. I. Vlasov
Data Analysis and Statistics · Cross-listed from stat.CO
`pandemonium`: High Dimensional Analysis in Linked Spaces
Gabriel McCoy, German Valencia and Ursula Laa
A common challenge in data analysis is uncovering relationships between predictors and responses in problems involving large numbers of both. When the number of predictors and responses is limited, visual approaches are particularly effective. We present an R package, pandemonium, designed to explore such problems by combining cluster analysis with linked visualisations. Clustering is performed in one set of variables to identify regions with similar patterns in that space. The resulting clusters are simultaneously visualised in both spaces using linked views based on non-linear dimension reduction and animated tours. We introduce the package through two examples that illustrate different types of linked spaces. In the first example, we consider how a set of input variables is mapped to latent activations in a neural network regression model, to identify input combinations that result in similar activation patterns. In the second example, we analyse a complex multivariable mathematical model arising in physics to investigate how structure in the predictor space relates to the responses.
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Optics
Spatiotemporal Electron Microscopy of Phonon Polaritons in MoO3
Harel Nahari, Yaniv Kurman, Raphael Dahan et al. (+5 more)
Photon-induced near-field electron microscopy (PINEM) has emerged as a powerful technique for imaging optical excitations with nanometer spatial and sub-picosecond temporal resolution. Recent years have extended the bandwidth of operation of PINEM experiments from the visible range to the mid-infrared, revealing the spatiotemporal dynamics of polaritons and their exotic phenomena. In this study, we nearly double the bandwidth of PINEM, going deeper into the infrared up to 12 um. Leveraging this advancement, we investigate the spatiotemporal dynamics of
phonon polaritons (PhPs) in {\alpha}-MoO3, a material of growing interest thanks to its in-plane anisotropy. Visualizing PhPs in a cavity-like flake reveals their spatial distribution, dynamics, and wavelength-dependent lifetime. Our work pushes the frontiers of PINEM imaging and highlights its potential for probing hard-to-access polaritonic properties of novel van der Waals materials.
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All authors Harel Nahari, Yaniv Kurman, Raphael Dahan, Yuval Adiv, Michael Yannai, Hanan Herzig Shenfux, Frank H.L. Koppens, Ido Kaminer
Data Analysis and Statistics · Cross-listed from stat.AP
Model-free estimation in scattering analysis of microscopy
Tong Lin, Jinseok Lee, Matt Helgeson et al. (+3 more)
The mean squared displacement (MSD) of particles or probes is commonly estimated from microscopy
videos using particle tracking approaches, which rely on tuning parameters manually, and are often unstable over the entire lag time range, especially in dense or low-contrast situations. In this work, we propose model-free ab initio uncertainty quantification (MF-AIUQ), a model-free method for scattering analysis of microscopy
video based on a probabilistic framework, which estimates MSD without isolating particles and linking their trajectories. Based on the relationship between the intermediate scattering function (ISF) and the MSD derived from the cumulant
theorem, MF-AIUQ estimates the MSD values by the marginal maximum likelihood
estimator. To reduce the computational cost, the likelihood function is approximated by a subset of
Fourier-transformed intensities. These intensities are equally spaced at the logarithmic values of
Fourier basis functions and lag time points. We found that the ISF is smooth in this logarithmic input space, and the information of the ISF can be captured by this subset of inputs. We examine the method through simulation studies covering several representative
stochastic processes and three experimental systems: a Newtonian fluid for evaluating performance in optically dense and bright-field settings, a gelation system with an evolving MSD shape, and snail mucin, a viscoelastic biopolymer, for modulus estimation. Across these studies, MF-AIUQ provides smooth and stable MSD estimates over the full lag time range and serves as a useful complementary approach in settings where particle tracking is unreliable or a parametric model of MSD is unavailable or unverifiable.
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All authors Tong Lin, Jinseok Lee, Matt Helgeson, Megan T. Valentine, Yimin Luo, Mengyang Gu
Medical Physics
Coupling Spectrum Estimation and Single Energy Material Decomposition via X-ray Grating Interferometry
Longchao Men, Peiyuan Guo, Jincheng Lu et al. (+5 more)
Dark-field imaging based on grating interferometry is an emerging X-ray modality in medical imaging, which is particularly capable of providing complementary diagnostic information by visualizing the microstructural properties of lung tissue. However, quantitative dark-field imaging remains fundamentally challenged by beam hardening, which arises from the energy-dependent fringe visibility under polychromatic illumination. The resulting artifacts substantially degrade the quantitative accuracy of dark-field images. In this work, motivated by our key observation of an intrinsic similarity between the X-ray energy spectrum and the system-related coupling spectrum, we propose a unified framework to simultaneously and independently estimate both spectra. By measuring the transmission associated with the zeroth- and first-order components of the phase-stepping curve using solid step-wedge phantoms, the two spectra are robustly estimated via an expectation-maximization
algorithm. The recovered spectra are subsequently incorporated into a physics-based correction model to mitigate beam-hardening-induced artifacts in dark-field imaging effectively. Furthermore, leveraging the inherent availability of two independent spectra within X-ray grating interferometry, we introduce a single-energy material decomposition method that achieves basis material imaging without dual-energy scans. Wave-optical simulations and experiments demonstrate accurate spectrum estimation, effective dark-field signal correction, and reliable material decomposition. Consequently, the proposed framework extends the diagnostic potential of X-ray grating interferometry beyond pulmonary imaging, facilitating broader applications in medical imaging.
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All authors Longchao Men, Peiyuan Guo, Jincheng Lu, Yan Xu, Hongxia Yin, Zhenchang Wang, Li Zhang, Zhentian Wang
Instrumentation and Detectors
Measurements and simulations of X-ray radiation damage effects on CNM n-type 4H-SiC MOS capacitors
Khaoula Aouadj, Alessandro Fondacci, Arianna Morozzi et al. (+7 more)
Silicon carbide is a promising material for radiation-hard detectors due to its wide bandgap, low leakage current, high critical electric field, and high saturation velocity. A key obstacle for its use in high-radiation environments is the incomplete understanding of surface damage at the 4H-SiC/SiO$_2$ interface.In this work, we present a combined experimental and TCAD simulation study of X-ray radiation-induced surface damage on n-type 4H-SiC MOS capacitors fabricated at CNM (Centro Nacional de Microelectronica, Barcelona), irradiated up to 10 Mrad. High-frequency (100 kHz) and quasi-static capacitance-voltage (C–V) measurements are used to evaluate the
evolution of fixed
oxide charge density and interface trap density as a function of dose.A dose-dependent TCAD surface model is developed and validated against the full set of measurements. The optimized model reproduces the measured C–V characteristics across the entire irradiation range and provides a physically grounded baseline for simulations of n-type 4H-SiC-based detectors. It can be used as a starting point for predictive modeling of irradiated detectors.
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All authors Khaoula Aouadj, Alessandro Fondacci, Arianna Morozzi, Daniele Passeri, Tommaso Croci, Sebastian Alexander Onder, Daniel Radmanovac, Thomas Bergauer, Serena Mattiazzo, Francesco Moscatelli
Optics
Source-driven torsional optical activity in geometrically chiral media
Edilberto O. Silva
We develop an effective field-theoretical model for source-driven electromagnetic waves in a geometrically
chiral optical medium described by a uniform axial torsion. Starting from the gauge-invariant electromagnetic field strength, we introduce a Chern–Simons-type coupling between the vector potential and the medium's axial contortion, thereby obtaining an inhomogeneous Maxwell system with prescribed external sources. For transverse cylindrical source profiles, we derive the coupled radial equations and solve them analytically for a circulating cylindrical-shell current. In the circular basis, the homogeneous problem diagonalizes, yielding torsion-split radial wavenumbers that give rise to longitudinal circular birefringence under guided-mode boundary conditions. In the weak-torsion regime, this birefringence produces a polarization rotation proportional to the propagation length and an oscillatory conversion between orthogonal linear polarizations. The source fixes the jump conditions and the relative excitation of the circular eigenmodes, thereby yielding measurable modal power and Poynting-flow signatures. A two-port scattering analysis shows that the apparent direction dependence remains Lorentz reciprocal, placing the effect in the class of reciprocal
geometric optical activity rather than Faraday isolation.
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Fluid Dynamics
Active phase-space topology unifies depletion and alignment in bacterial flows
Mingyang Guan, Bowen Ling, Enhao Liu et al. (+2 more)
Transport at small scales is classically understood within an
equilibrium framework, where dispersion theory successfully describes shear-enhanced
diffusion for passive particles in the continuum limit. However, as most bacteria can move on their own, their motility in flows, inherently out of thermal
equilibrium, fundamentally challenges this framework. A minimal, predictive unified theory of bacterial transport in low-Reynolds-number flows remains lacking. Here, from first principles, we develop an analytical hydrodynamic model that enforces consistent no-flux boundary conditions and uses the method of images to characterize the flow-wall coupling. The model quantitatively reproduces measured bacterial distributions and reveals a hydrodynamic locking mechanism accompanied by mean-drift invariance – an active counterpart to Taylor dispersion. We clarify that shear-induced depletion and
alignment are dual manifestations of a single active phase-space
topology, ruling out explanations based solely on the local shear magnitude. The theory is validated against microfluidic experiments spanning multiple bacterial species and shear geometries, from one-dimensional to fully three-dimensional flows. Our findings establish a unified phase-space framework for bacterial hydrodynamics, advancing the fundamental understanding of active matter.
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All authors Mingyang Guan, Bowen Ling, Enhao Liu, Guoqian Chen, Zhan Wang