Optics · Cross-listed from quant-ph
From Solid-State Spin Defects to Fluorescent Proteins: A Perspective on Quantum Optical Sensing Platforms for Biomedical Applications
Jyotiprakash Parhi, Ayan Majumder and Kasturi Saha
Quantum optical sensing has evolved from isolated solid state
spin defect platforms to increasingly bio-integrated systems designed for biomedical applications. This review presents a perspective on this transition, spanning nitrogen vacancy centers in diamond to emerging fluorescent
protein based
spin qubits. Advances in diamond fabrication have enabled photonic cavities, nanomechanical resonators, and microstructured devices that enhance
spin photon interactions and room temperature sensitivity. Exploration of
spin defects in alternative materials further expands the sensing landscape. Parallel progress toward biological compatibility includes chip based architectures for in vitro and in vivo studies, microfluidic integration, and minimally invasive nanodiamond probes capable of intracellular nanothermometry and nanorheometry. Improvements in surface functionalization have enhanced coherence and sensing reliability in complex environments. Collectively, these advances highlight the progress and remaining challenges toward application oriented
quantum sensing for the life sciences.
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Plasma Physics
Imaging ablator-fuel mix of hot spot in inertial confinement fusion via resonant X-ray absorption using an X-ray free electron laser
Lingen Huang, Long Yang, Alejandro Laso Garcia et al. (+44 more)
A novel diagnostic is proposed for active probing of doped inertial confinement fusion (ICF) spherical shells, enabling direct measurements of mix and burn dynamics at next-generation implosion facilities via resonant absorption imaging with an X-ray free-electron
laser (XFEL). The charge-state-sensitive imaging of embedded dopants provides spatiotemporally resolved constraints on ionization, opacity, and material mix seeded by hydrodynamic instabilities in stagnated
plasmas. Proof-of-principle experiments demonstrating resonant XFEL probing of hot spot in coated copper wires driven by an ultra-short relativistic
laser pulse, have established the feasibility of this approach. Furthermore, atomic and radiation-hydrodynamic simulations, combined with synthetic resonant X-ray absorption imaging, extend the diagnostic concept to
laser-driven direct-drive ICF shells with copper-doped ablators and radiation-driven indirect-drive shells with tungsten-doped ablators. This unique approach, combining a
laser-driven implosion facility with a high-brightness XFEL, could enable precise measurements of fusion-relevant hot dense
plasmas at multi-keV temperatures, provide stringent
benchmarks for radiation-hydrodynamics models, and advance the realization of inertial fusion energy.
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All authors Lingen Huang, Long Yang, Alejandro Laso Garcia, Oliver S. Humphries, Michal Šmíd, Mikhail Mishchenko, Victorien Bouffetier, Carsten Baehtz, Erik Brambrink, Samuele D. Di Dio Cafiso, Gabriel Pérez-Callejo, Yangzhe Cui, Thea Engler, Wen Feng, Sebastian Göde, Joerg Grenzer, Christian Gutt, Johannes Hagemann, Marie-Luise Herbert, Arthur Hirsch-Passicos, Hauke Höppner, Thomas Kluge, Dominik Kraus, Julian Lütgert, Masruri Masruri, Motoaki Nakatsutsumi, Özgül Öztürk, Paweł Ordyna, Xiayun Pan, Franziska Paschke-Bruehl, Alexander Pelka, Thomas R. Preston, Chongbing Qu, S.V. Rahul, Lisa Randolph, Martin Rehwald, Hans-Peter Schlenvoigt, Samuel Schumacher, Ulrich Schramm, Jan-Patrick Schwinkendorf, Georgiy Shoulga, Monika Toncian, Jan Vorberger, Karl Zeil, Ulf Zastrau, Toma Toncian, Thomas E. Cowan
Optics
Undetected Photon Spectroscopy in the Long-wave and Far Infrared
Jinghan Dong, Jingrui Zhang, Haichen Zhou et al. (+3 more)
Spectroscopy with undetected
photons allows the spectral response of a sample at long wavelengths to be measured through interference of a shorter-wavelength signal field, without directly detecting the light that probes the sample. Previous demonstrations of undetected-
photon spectroscopy in the molecular fingerprint region have reached approximately 10.5 microns, leaving longer wavelengths largely unexplored. Here, we extend this approach to 20 microns wavelength, demonstrating infrared undetected-
photon spectroscopy using a BaGa2GeSe6 (BGGSe)-based nonlinear interferometer while only the near-infrared (NIR) signal is detected using a silicon detector. Rotation of the BGGSe
crystal provides broad wavelength tuning, and
Fourier-transform analysis of the signal interferograms yields the corresponding idler spectra and sample transmittance. Broadband absorption spectroscopy is demonstrated using Kapton across a 7.8-20 microns wavelength range, with the measured absorption agreeing with independent infrared measurements. The same system is further employed to detect sulfur hexafluoride (SF6) gas via spectroscopy near 10.55 microns. These results substantially extend the accessible spectral range of spectroscopy with undetected
photons while retaining silicon-based NIR detection.
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All authors Jinghan Dong, Jingrui Zhang, Haichen Zhou, Weijie Nie, John G. Rarity, Alex S. Clark
Physics and Society
Breaking Behavioral Uniformity in Traffic Flow: Analytical Derivation and Numerical Verification of Optimal Cooperative Buffering
Raphael Korbmacher and Antoine Tordeux
Stop-and-go waves pose a persistent challenge in traffic flow theory, significantly compromising highway safety, operational efficiency, and environmental sustainability. This paper mathematically derives an optimal cooperative driving policy based on the premise that connected vehicles can cooperate and assume distinct roles. In doing so, we depart from the classical assumption of uniform vehicular behavior. Through a rigorous optimization formulation constrained by linear stability conditions, it is analytically proved that the traffic system's throughput is globally maximized when a single designated "buffer" vehicle maintains an enlarged headway to absorb perturbations, enabling the remaining vehicles to form a tightly spaced, high-capacity platoon. This analytically derived optimum is confirmed via numerical spectral analysis and stability-constrained flow optimization using the Intelligent Driver Model and the Full Velocity Difference Model. The results demonstrate that this non-uniform cooperative buffering strategy yields dual benefits. It radically expands the string-stable parameter space to actively dissipate SGWs, while simultaneously achieving significantly higher traffic flow compared to both unbuffered traffic and non-cooperative Jam-Absorption Driving strategies.
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Optics
Learning qBIC Resonances across Metasurface Families in Dielectric Fourier Space
Shuangteng Lei, Li Yu, Tianxin Li et al. (+1 more)
Bound states in the continuum (BIC) metasurfaces are typically described by geometry-specific parameters, hindering cross-geometry comparison, while ultranarrow qBIC features are easily diluted in full-spectrum learning. Here, 2015 samples from seven dielectric metasurface families are mapped to a shared reciprocal-
lattice grid, where two frozen low-order
Fourier channels capture resonance shifts with mean within-branch $R^2$ values of 0.871-0.999. Field-level analysis of two representative branches further confirms that these shifts are consistent with the Maxwell-
Fourier perturbation picture. A five-channel K-space backbone models the broadband spectrum, while a local complex K-space expert parameterizes the qBIC resonance through a differentiable Fano layer. The expert reduces resonance-position mean absolute error (MAE) from 3.2 to 0.95 nm and the resonance-depth error by 14-fold on a geometry-blocked test set. The same coordinate supports spectrum-to-structure reconstruction.
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All authors Shuangteng Lei, Li Yu, Tianxin Li, Wei Lu
Atomic Physics
Response of the near-threshold resonances of the $\bm{dt\mu}$ molecular ion to an effective atomic $2s$–$2p$ splitting
Yi Zhang
For the nonrelativistic three-body Coulomb
Hamiltonian, near-threshold resonances of the deuterium–tritium muonic molecular ion ($dt\mu$) are supported by the long-range dipole coupling between degenerate atomic $2s$ and $2p$ states. We study the effect of atomic $2s$–$2p$ splitting on their positions and decay widths. Three-body complex-absorbing-potential calculations resolve additional members of the $L^\pi=0^+$ and $1^-$ series. Their
geometric spacing agrees with that expected from the $1/R^2$ dipole attraction, where $R$ is the atom–
nucleus separation. To assess the effect of splitting, we scan a prescribed $2s$–$2p$ interval using an effective potential in a
spin-independent, nonrelativistic
Hamiltonian. This models the atomic splitting without an explicit Lamb-shift calculation. Within this model, the studied resonances lie closer to the $d\mu(2s)+t$ threshold and have smaller Coulomb decay widths than in the degenerate case. At an effective interval of $0.2\eV$, the seventh $1^-$ member lies within $2\meV$ of this threshold with a full width of about $4\meV$, compared with $48$ and $15.6\meV$ at degeneracy. These values characterize the response within the tested numerical representations. Its width decreases, but its separation from the threshold decreases more strongly. The long-range analysis attributes these shifts and width reductions to modified dipole mixing. It further suggests that atomic $2s$–$2p$ splitting may truncate the infinite accumulation of resonances predicted for degenerate atomic $2s$ and $2p$ levels.
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Data Analysis and Statistics · Cross-listed from cond-mat.mtrl-sci
Generation, Accumulation, and Utilization of Data in the Automatically Controlled End-Station of a Soft X-ray Beamline
Yasunobu Ando, Masashige Miyamamoto, Keita Hiromori et al. (+4 more)
AI is rapidly transforming materials exploration, yet reliable AI-assisted research depends on experimental data that retains their context, provenance, and machine-readable structure. High-throughput synchrotron measurements therefore require more than automated data acquisition: data generation, accumulation, and utilization must be connected within a continuous workflow. Here, we present a data-centric research framework that integrates the PIONEER system, the OMNES, and ML analysis. The PIONEER system automates sample handling,
vacuum transfer, and scanning XAS at the BL08U soft X-ray beamline of NanoTerasu, systematically generating large volumes of spatially resolved spectral data. Measurement and analysis files are stored in the cloud-based ARIM-mdx data system, while OMNES manages metadata describing samples, preparation procedures, measurement conditions, instrument settings, data locations, and analysis histories. Tabular and JavaScript Object Notation formats are used according to the metadata structure, with numerical values stored separately from units to facilitate machine processing. OMNES organizes these records based on causal relationships among experimental and analytical processes, linking samples, measurements, raw data, processed data, and analysis results through a relational data model and visualizing their relationships as a graph. This causality-based organization preserves experimental and analytical provenance and clarifies how each result was derived from the preceding processes and data. The accumulated spectra can subsequently be processed using ML methods, including dimensionality reduction and materials classification, and the resulting data can be registered back into OMNES. Previously reported ML analysis of BN XAS spectra is presented as an example of the analytical workflow that can be applied to data acquired at the beamline.
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All authors Yasunobu Ando, Masashige Miyamamoto, Keita Hiromori, Takeru Nakashima, Masafumi Horio, Masato Kotsugi, Iwao Matsuda
Fluid Dynamics
Net drag reduction in turbulent pipe flow by airfoil-section grids concentrated near the wall
Takuya Masuda
The frictional drag of turbulent pipe flow is responsible for enormous energy consumption in water and natural gas distribution systems. Flow straighteners can reduce this drag by suppressing
turbulence, but they generally induce a pressure loss that exceeds the reduction; similarly, large-eddy breakup devices installed in pipes have not achieved a net drag reduction. In this study, a grid of NACA0006 airfoils was adopted as a flow straightener to suppress the pressure loss, and its net drag reduction was evaluated by numerical simulations using the $k$-$\omega$ shear stress transport model of the axisymmetric Reynolds-averaged Navier-Stokes equations with periodic boundary conditions. The model was validated against fully developed turbulent pipe flow and a previous experiment on a large-eddy breakup device in a pipe. Under a pressure difference corresponding to a Reynolds number ($\mathit{Re}$) of approximately $10^5$, a grid pattern of concentric rings concentrated near the wall at an axial spacing of 0.5 m increased the flow rate by up to 9.0%, and the flow rate increase remained positive for $5 \times 10^{4} \leq \mathit{Re} \leq 2 \times 10^{5}$. The grid pattern reduced the area-integrated Reynolds shear stress by 29% and brought the velocity profile closer to a laminar one. The effectiveness of the near-wall placement is consistent with the Fukagata-Iwamoto-Kasagi identity, which weights the Reynolds shear stress more heavily closer to the wall.
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Optics
Simulations of Fluorescence and Energy Transfer in Periodic Systems: Pitfalls and Considerations for Bound States in the Continuum
Ilia Lykov, Sergejs Boroviks and Olivier J. F. Martin
Bound states in the continuum (BICs) combine high quality factors with strong electromagnetic-field localization and are therefore widely explored for enhancing light–matter interactions. However, large field amplitudes do not directly translate into useful fluorescence enhancement or energy transfer enhancement between two donor–acceptor fluorophores. Here, we investigate this question for a hybrid plasmonic–photonic resonant waveguide grating supporting a
symmetry-protected BIC. We emphasize some of the pitfalls associated with the numerical simulations, especially the utilization of periodic boundary conditions for fluorescence. Strong BIC-related fields can enhance acceptor absorption while useful fluorescence enhancement remains moderate. Extensive simulations and the comparison of different figures of merit, indicate that, while a BIC can suppress radiative leakage, it can also redirect a large fraction of the energy into Ohmic losses. As a result, the useful fluorescence enhancement of donors remains moderate, whereas absorption by acceptors can be strongly enhanced in Förster resonance energy transfer (FRET) experiments. It is essential to separate near-field FRET from long-range energy transfer and reabsorption mechanisms, both of which are mediated by the delocalized BIC mode. Finally, results obtained for finite gratings are compared with infinite periodic simulations and conceptual inconsistencies explained. This work provides a consistent framework for interpreting fluorescence, absorption, and energy transfer in BIC-based periodic nanophotonic systems.
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Optics
Inverse Design of Integrated Photonic Components for Visible-Light Applications
Christoph Stockinger, Marko Šimić, John O. Adeniran et al. (+3 more)
Photonic integrated
circuits (PICs) operating in the visible spectral range are crucial for
quantum technologies, optical sensing, and nonlinear optics applications. However, their development is hampered by limited integration density and operational bandwidth, linked to low refractive index contrast and restricted parameter space in intuition-based PIC design. We address these bottlenecks with an adjoint-based, fabrication-aware inverse design workflow tailored for visible-spectrum photonics. By expanding the capabilities of FDTDX, an open-source, GPU-accelerated FDTD solver, we provide a versatile
memory and runtime efficient inverse design platform. Demonstrating this approach on a silicon nitride (Si3N4) platform, we design, fabricate, and experimentally validate ultra-compact, broadband components for light routing, multiplexing, and polarization control. This work provides a scalable framework for high-density, high-performance visible-light PICs.
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All authors Christoph Stockinger, Marko Šimić, John O. Adeniran, Natale G. Pruiti, Marc Sorel, Peter Banzer
Applied Physics
Time-Domain Analysis of Surface Acoustic Wave Magnetoelectric Sensors
Mohsen Samadi, Henrik Wolframm, Felix Weisheit et al. (+4 more)
The transient response of surface acoustic wave sensors is important for understanding their dynamic behavior, propagation delay, and response to time-varying signals. In this work, the time-domain propagation characteristics of a magnetoelectric SAW sensor based on a multilayer Love-wave delay line are investigated using complementary numerical and experimental approaches. Time-domain analysis is employed to determine the delay time and to extract the phase and group velocities, while frequency-domain analysis provides an independent characterization of the wave dispersion. Both numerically and experimentally, the phase and group velocities are found to differ, reflecting the dispersion of the Love wave in the multilayer structure. At the operating frequency of 146 MHz, the simulated group velocity obtained from wave-field tracking agrees within 0.4% with the value determined from the frequency-domain dispersion relation. The simulated delay time and group velocity also show good agreement with experiment, with deviations of 2.7% in delay time and 0.9% in group velocity. These results demonstrate the consistency of the time- and frequency-domain analyses and provide a quantitative characterization of the transient propagation behavior of SAW sensors.
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All authors Mohsen Samadi, Henrik Wolframm, Felix Weisheit, Dirk Meyners, Eckhard Quandt, Michael Höft, Martina Gerken
Optics
Engineering Photon Avalanche Thresholds in Single Nanocrystals with Plasmonic Nanostructures
Marcin Szalkowski, Maciej Fryckowski, Małgorzata Misiak et al. (+3 more)
Optical sub-diffraction imaging has become an essential tool in modern research. Recently, a new imaging strategy has been demonstrated that exploits the strongly nonlinear excitation-emission response of rare-earth-doped nanocrystals operating in the
photon avalanche (PA) regime. This approach benefits from simple optical instrumentation, near-infrared excitation and emission, low cytotoxicity, and high photostability. However, its practical implementation is hindered by relatively high (10-100s of kW/cm2) excitation power densities required to initiate the PA process. We aim to mitigate this limitation through electromagnetic field enhancement provided by metallic nanostructures. The results of microscopic studies of individual
photon-avalanching nanocrystals coupled to a silver island film demonstrate a greater than tenfold reduction in the excitation power density required to trigger the avalanche emission. These experimental results, corroborated by numerical modelling, which elucidates the role of plasmon-mediated electromagnetic field enhancement in modifying the
photon avalanche dynamics, paves the way towards new generation of low excitation power probes for sub-diffraction imaging and sensing.
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All authors Marcin Szalkowski, Maciej Fryckowski, Małgorzata Misiak, Artur Bednarkiewicz, Dawid Piątkowski, Sebastian Maćkowski
Instrumentation and Detectors
Autocorrelation-based beam shape optimization in scanning electron microscopy
Rebecca Guan, Andreas Werbrouck, Matthew M. Maschmann et al. (+1 more)
Many automatically focusing
algorithms for scanning electron microscopes exist. Typically, these optimize a single derived metric (such as image sharpness) without considering the intrinsic beam shape. We describe an
algorithm to automatically focus and stigmate scanning electron microscopes based on the autocorrelation of captured images. In the first part of this work, we develop the theoretical basis of using the autocorrelation to approximate the current beam shape. In the second part, we use this to condition the beam shape on various surfaces, using
Bayesian optimization to tune both working distance and, in particular, stigmation. Through a comparison of the full width at half maximum of the autocorrelation arrays before and after optimization and a visual comparison of images taken of the sample surface before and after optimization, we show that the
algorithm is able to successfully optimize the scanning parameters. Overall, our
algorithm can effectively focus on a variety of topographies at different magnifications.
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All authors Rebecca Guan, Andreas Werbrouck, Matthew M. Maschmann, Matthias J Young
Optics
Impact of Stimulated Brillouin Scattering on Modulation Instability in Fiber Fabry-Perot Resonators
Alice Houard, Thomas Bunel, Matteo Conforti et al. (+2 more)
We report the experimental and numerical demonstration of stimulated Brillouin scattering-induced stabilization of Kerr-driven modulation instability in fiber Fabry–Perot resonators. We show that Brillouin scattering shapes the modulation instability spectrum into a stable multi–free-spectral-range cascade that is otherwise unstable in the absence of Brillouin effects. We further identify that this stabilization originates from the real part of the Brillouin response, leading to an asymmetric Kerr-Brillouin interaction governed by the relative position of the Brillouin frequency shift with respect to the cavity resonances. These results establish stimulated Brillouin scattering as an additional degree of freedom for controlling nonlinear dynamics in Kerr resonators.
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All authors Alice Houard, Thomas Bunel, Matteo Conforti, Saliya Coulibaly, Arnaud Mussot
Atmospheric and Oceanic Physics
A Physics-Constrained Implicit Profile Network for Continuous Reconstruction of Tropical Cyclone Near-Surface Wind Profiles
Jian Ma, Yilin Yang, Robert Rogers et al. (+2 more)
Near the ocean surface, tropical cyclone winds change rapidly with height, but direct measurements are limited because aircraft dropsondes provide only sparse and irregular observations. Continuous wind profiles are important for understanding hurricane boundary-layer processes, improving storm-surge prediction, supporting offshore engineering, and assessing coastal hazards. In this study, we developed an artificial intelligence model that combines machine learning with physical principles to reconstruct continuous wind profiles from sparse observations. The model is designed to preserve the observed surface winds while generating realistic changes in wind speed and direction with height. Tests using more than two decades of NOAA hurricane observations show that the method accurately reproduces the vertical structure of tropical cyclone winds over a wide range of storm intensities. The framework can also extend satellite-derived surface wind measurements into three-dimensional near-surface wind fields, providing new opportunities for hurricane research, operational forecasting, and engineering applications.
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All authors Jian Ma, Yilin Yang, Robert Rogers, Jun A. Zhang, Jie Tang
Fluid Dynamics
Inertialess instability of elasto-viscoplastic circular Couette flow
James D. Shemilt, Neil J. Balmforth and Duncan R. Hewitt
An exploration is presented of two-dimensional, circular Couette flow of an elasto-viscoplastic fluid described by Saramito's (Bingham) constitutive law. Axisymmetrical base states are constructed. As has been noted previously, such states are not unique, with stresses over any plugs depending on the initial
polymer stress, and the shear rate and stress may jump discontinuously across the yield surfaces. We show that base states with continuous stress profiles are linearly unstable at zero Reynolds number when they contain regions with relatively low shear rate. Unstable modes become stronger and localized to the yield surfaces as the azimuthal wavenumber increases. We report numerical simulations exploring the nonlinear dynamics of the instability. The linear unstable modes saturate at finite amplitude to create spatio-temporally complicated states.
Polymer stress
diffusion is added to ease these numerical simulations, eliminating normal-stress discontinuities and instability at the shortest wavelengths. Instability and transition to complex dynamics occur whenever the base flow contains regions with relatively low shear rate.
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Instrumentation and Detectors
From Tunnel Overburden Reconstruction to Tidal Measurements via atmospheric muon
Jiwon Seo, Jongseok Chung, Chang Hyon Ha et al. (+8 more)
Muography with scintillator-based detectors enables the investigation of density distributions within large structures. The Hankuk Atmospheric-
muon Wide Landscaping (HAWL) project is the first real-time portable
muon tomography. It successfully charted the mountainous region of eastern Korea by measuring
cosmic-ray
muons with a detector operated in a moving vehicle. HAWL achieved a tunnel length accuracy of 6.0 % and an overburden measurement range of 8-400 meter-water-equivalent (m.w.e.). The HAWL upgrade (HAWLU) features a more compact design and enables trajectory reconstruction. Using this upgraded system, we measured tidal water-level variations with meter-scale precision over 31.6 days in the Boryeong Undersea Tunnel. The measured
muon rate decreased by $1.72 \pm 0.04$ % per meter of increasing tidal level, while the reconstruction of undersea tunnel scan independently validated the detector performance. These results demonstrate the capabilities of dynamic muography in two approaches, one with a portable detector in motion and the other with a detector measuring a target that changes over time.
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All authors Jiwon Seo, Jongseok Chung, Chang Hyon Ha, TongZhou Huang, Jinyoung Kim, Sooa Kim, Hani Kimku, Byoung-cheol Koh, Minsu Kwak, Sihyun Lee, Yujin Lee
Plasma Physics
Contributions of the breathing waveform and residual fluctuations to power and higher-order spectra in a Hall-thruster plume
Zilong Peng, Baisheng Wang, Zhongping Zhao et al. (+4 more)
Higher-frequency power in Hall-thruster plume-probe signals can arise from both harmonics of a repeatable breathing waveform and fluctuations about it, complicating spectral interpretation. We decompose 197 paired records from 20 sequentially sampled probe-pair geometries at one operating condition, estimating each phaseconditioned waveform from other records at the same geometry. The residual accounts for 87.1% and 99.7% of measured power in the 0.2-0.5 and 0.5-1 MHz bands, respectively, as medians across geometries. The repeatable waveform, however, reproduces the principal breathing-harmonic bicoherence structure. Residual power remains modulated by breathing phase after waveform removal, exceeding geometry-specific 95thpercentile circular-shift thresholds in both bands at all 20 geometries. Residual bicoherence is substantially weaker than that of the measured signal but exceeds record-specific random-phase thresholds in 195 of 197 records. An exact component expansion further shows that the all-waveform term dominates a specified signed third-order statistic over the fixed 50-80 kHz band near the second breathing harmonic. These results distinguish band-power allocation from harmonic organization within the evaluated frequency ranges. The attribution concerns uncalibrated probe-chain signals and does not identify distinct physical modes or measure energy-transfer rates. The findings motivate assessing repeatable-waveform contributions before interpreting breathing-harmonic bicoherence as evidence of interactions among residual fluctuations.
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All authors Zilong Peng, Baisheng Wang, Zhongping Zhao, Yao Tang, Yinjian Zhao, Daren Yu, Ming Zeng
Data Analysis and Statistics · Cross-listed from cond-mat.mtrl-sci
Data-Driven Variable-Exponent Analysis for Photoemission Yield Spectroscopy: An Autonomous Self-Diagnosing Framework Based on Integrated Residual Metrics
Shinjiro Yagyu, Takahiro Nagata and Yoshiyuki Nakajima
Photoemission yield spectroscopy (PYS) is widely used for evaluating the electronic states of materials. As automated materials discovery advances, unsupervised extraction of physical information from ambient-air PYS data becomes important. Conventional fixed-exponent analyses and logarithmic transformations suffer from heteroscedasticity, which destabilizes estimation in low-signal regions. To address this, we propose a data-driven analysis framework based on the 1/n-Scan method, which operates directly in the original signal space, removing the
geometric bias inherent in log-transform approaches. We further integrate a self-diagnostic quality-evaluation system that quantifies estimation uncertainty with Akaike weights, together with independent residual metrics–the normalized mean absolute error (NMAE), the RMSE-to-MAE ratio (RMR), the Durbin-Watson (DW) statistic, and a macroscopic metric ($\Delta R^2$)–that distinguish hardware-related data degradation from a physical-model mismatch. Applying the framework to differently doped Si and a polycrystalline Au reference in air, we demonstrate autonomous detection, without assumptions on the emission mechanism, of the breakdown of the single-component approximation in heavily doped p-type Si, arising from the overlap of two emission components with different thresholds, as a statistical anomaly–a decrease in DW below its critical value with an auxiliary increase in $\Delta R^2$, despite sound NMAE and RMR–independently confirmed by a two-component fit ($\Delta$AIC $\approx$ 57, DW recovering from 0.8 to 2.0). For heavily doped n-type Si, the gradual surface
evolution was classified as a change within the single-component description. This framework provides a robust, self-diagnosing analysis engine for closed-loop autonomous materials exploration.
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Chemical Physics
Isotope Effects at Classical Cost through Mass-Differentiable Machine Learning
Ming-Zheng Du, Shi-Yu He, Jing Shen et al. (+5 more)
Isotope effects govern fractionation and modulate reactivity, with applications from hydrogen energy to environmental science and catalysis, yet predicting them requires resolving small isotope-dependent free-energy differences that remain very challenging for conventional path-integral simulations in complex systems. Here we introduce iso-EPIGS, a path-integral coarse-graining framework built on a mass-differentiable neural network that reconstructs the mass- and temperature-dependent path integral centroid free-energy surface. Classical molecular dynamics on the learned surface yields rigorous isotope-resolved thermodynamics without explicit path-integral sampling.
Benchmarks spanning gas,
liquid, and crystalline phases, including
liquid water and oxalic acid
crystal, reproduce reference path-integral isotope free-energy differences, enthalpies, and
lattice parameters at near classical computational cost. Crucially, iso-EPIGS trained solely on all-H and all-D isotopologues retains high accuracy for unseen partially deuterated isotopologues, demonstrating robust transferability across nuclear masses. Iso-EPIGS makes accurate isotope-effect simulations feasible for complex systems and lays the groundwork for foundation models of isotope effects across chemical space.
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All authors Ming-Zheng Du, Shi-Yu He, Jing Shen, Ziyan Ye, Jia-Xi Zeng, Dong H. Zhang, Venkat Kapil, Wei Fang
Optics
Full-Vector Diffractive Deep Neural Networks
Shengmei Zhao, Gongyuan Wang, Zhiwan Wang et al. (+2 more)
Conventional diffractive deep neural networks (D2NNs) treat polarization as independent channels and rely on scalar or semi-vectorial propagation models, which neglect cross polarization coupling and vector diffraction. Here we propose a vector D2NN (V-D2NN) that embeds the full vector angular spectrum method into the end-to-end training pipeline. This physically rigorous framework describes vectorial light-matter interactions across cascaded diffractive layers, enabling direct optimization of polarization conversion,
spin-orbit coupling, and vectorial interference without external polarization optics. We demonstrate the V-D2NN on polarization-multiplexed tasks–ector beam generation, polarization dependent imaging and classification, and multiple channel optical encryption–where it consistently outperforms scalar and semi-vectorial counterparts. In longitudinal-field engineering, the V-D2NN actively shapes a prescribed longitudinal field with a normalized correlation of 0.839, a capability inaccessible to scalar-propagation models. An open-source training framework is also provided to support further development of vectorial diffractive optics for computing, sensing, and communications.
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All authors Shengmei Zhao, Gongyuan Wang, Zhiwan Wang, Jianan Shao, Haolin Liu
Classical Physics
On-Chip Shaping of Surface Acoustic Waves via Continuous Diffractive Modulation
Yuanpeng Ma, Yang Zhao, Shangyang Chen et al. (+4 more)
Precise shaping of surface acoustic waves (SAWs) on anisotropic piezoelectric substrates is complicated by elastic anisotropy and electromechanical coupling. Here we introduce a continuous diffractive acoustic lens (CDAL), in which weak phase-velocity perturbations produced by subwavelength metallization, together with diffraction, drive lateral field redistribution. An anisotropic thin-element propagation model enables efficient inverse design of the CDAL contour.
Laser Doppler vibrometry verifies prescribed lateral field profiles and multichannel beam splitting with unequal widths. By combining continuous diffractive modulation with discrete source-phase encoding, we further shape the lateral field into a Bessel profile, demonstrating joint amplitude-and-phase control. This work provides a high-precision and fabrication-compatible mechanism for on-chip SAW field modulation.
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All authors Yuanpeng Ma, Yang Zhao, Shangyang Chen, Dachuan Sang, Sicheng Wang, Dong Zhang, Xiasheng Guo
Applied Physics · Cross-listed from cond-mat.supr-con
High-Efficiency and Large Supercurrent Rectification with Superconducting Coil
Takumi Ichikawa, Daisuke Takegami, Gen Nishijima et al. (+8 more)
Superconducting diodes (SDs) are devices that rectify supercurrent through the difference in the superconducting critical current (Ic) between forward and reverse current directions. For bringing such SDs closer to practical superconducting power electronics applications, a combination of both high rectification efficiency ({\eta}) and a large Ic difference ({\Delta}Ic) is required. Here, we propose and demonstrate a coil-shaped superconducting wire device concept to induce a large SD effect, arising from the compensation between an external
magnetic field (Hext) and the field generated by the coil itself. From transport Ic measurements on coil-shaped SDs based on a Sn10-Pb90 solder wire, we achieved a {\eta} of 79% with a {\Delta}Ic of 140 A at Hext = 500 Oe (coil #2) and a {\eta} of 84% with a {\Delta}Ic of 125 A at Hext = 530 Oe (coil #3), confirming high rectification values at large supercurrents. The large-current high-efficiency SDE in the coil-shaped SDs will be highly useful for developing the potential field of supercurrent power electronics.
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All authors Takumi Ichikawa, Daisuke Takegami, Gen Nishijima, Shunsuke Kawakami, Tsutomu Nojima, Yuji Tsuchiya, Satoshi Awaji, Fuyuki Ando, Ken-ichi Uchida, Yuya Hattori, Yoshikazu Mizuguchi
Plasma Physics · Cross-listed from astro-ph.SR
Direct Numerical Comparison of Data Driving Strategies for Solar Flux Emergence in Magnetohydrodynamics: B-driving vs E-driving
Kyriakos Christos Tapinou, Axel Raboonik, David I. Pontin et al. (+3 more)
Data driving is an important technique for modelling realistic
magnetic field and
plasma evolution in regions of the solar atmosphere where direct observations are either absent or insufficient. This technique uses observational data to drive the
evolution of the simulation, while the modelled solar atmosphere evolves self-consistently. A common approach for data-driven simulations is B-driving, which uses the observed
magnetic field at the surface of the Sun as a boundary condition. However, only prescribing B at the boundary does not generally determine its numerical
evolution when the update depends on the reconstructed interface states or fluxes. To address this, E-driving provides an alternative approach by instead driving the simulation using the electric field on the boundary, which directly controls the
magnetic field update. We systematically quantify the performance of B- and E-driving in a controlled set of numerical experiments. We test both methods in the Athena++ solver using (a) an analytical flux-emergence model (Y. Fan & S. Gibson 2003) and (b) a "ground-truth" reference simulation (S. Toriumi & S. Takasao 2017; S. Toriumi et al. 2020) of active region emergence. For E-driving, the electric field is incorporated into Athena++'s constrained-transport (CT) update, preserving the discrete solenoidal constraint. We assess the reproduction of (i) boundary
magnetic flux, (ii) relative
magnetic helicity, (iii) total and free
magnetic energy, and (iv)
magnetic morphology. Across these diagnostics, E-driving gives better overall reproduction of the reference
evolution than B-driving. For the configurations considered in an Eulerian CT scheme, E-driving is more accurate than the commonly used ghost-
cell B-driving strategies and simpler than constructing an update-consistent B-driving boundary condition.
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All authors Kyriakos Christos Tapinou, Axel Raboonik, David I. Pontin, Michael S. Wheatland, Mark C.M. Cheung, Hannah Schunker
Optics
Optical Signals Synthesized from an Optical Lattice Clock with Uncertainty of 1.3E-17
Yuan Yao, Jinpeng Zou, Haosen Shi et al. (+3 more)
We report an accurate optical frequency synthesizer, which can generate single-frequency
laser light with high frequency stability and accuracy at desired frequencies over a wide optical region. The frequency of the output signal is divided from an 171Yb optical
lattice clock via an accurate optical frequency divider based on an optical frequency comb. Therefore, the output of the optical frequency synthesizer inherits the frequency accuracy from the Yb optical clock. The frequency uncertainty of the 171Yb optical
lattice clock is evaluated to be 6.8 mHz, corresponding to a fractional frequency uncertainty of 1.3E-17, mainly limited by the blackbody radiation shift and the
lattice-induced light shift.
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All authors Yuan Yao, Jinpeng Zou, Haosen Shi, Hongfu Yu, Longsheng Ma, Yanyi Jiang
Physics and Society
Energy-barrier characterization of secured basins in coupled oscillators with inertia
Jaiyong Lee, Daekyung Lee, Seung-Woo Son et al. (+3 more)
The second-order Kuramoto model captures rotor dynamics relevant to synchronization in power grids. In actual power grids, violation of angle-stability limits can trigger protective actions that are not included in the model, restricting its validity to trajectories that remain within these limits. We therefore define the secured basin as the region of disturbance space comprising disturbances whose trajectories remain within the angle-stability limits throughout the transient. We then characterize the secured basin through energy barriers, quantifying their characteristic energy scale and heterogeneity across perturbation directions. Across seven power-grid models, this characterization revealed angle-stability vulnerabilities overlooked when stability is assessed solely by the final synchronization state. It also showed that the two energy-barrier measures characterizing the secured basin exhibit distinct associations with structural connectivity and dynamical parameters. This characterization further offers practical advantages, as energy thresholds derived from state-space perturbations remain effective in distinguishing secured and unsecured outcomes under short-duration power disturbances and can be estimated efficiently by concentrating simulations near the secured-basin boundary. Overall, the secured-basin framework provides a useful basis for distinguishing node-level structural and dynamical influences on transient stability in oscillator networks with synchronization constraints.
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All authors Jaiyong Lee, Daekyung Lee, Seung-Woo Son, Sang Hoon Lee, Mi Jin Lee, Heetae Kim
Biological Physics · Cross-listed from q-bio.NC
If the brain were so simple: Information-based drivers of intelligence and their interaction through an n-body-inspired framework
Brett J. Kagan, Johnson Zhou, Forough Habibollahi et al. (+1 more)
Theories of how the
brain processes information and returns intelligent outputs are numerous and often difficult to conclusively test. Here, we consider an approach grounded in informatics and algorithmic thermodynamics for how neural systems respond to different patterns of information in different ways, with a focus on the relationship between the information
entropy of a signal and a new proposed quantity we term information enthalpy, which represents the internal resource of structured information within a system available to be used for predictions and other forms of work. To evaluate the capacity of the external signals to increase information enthalpy in the system, we introduce the information enthalpy potential (IEP) as a defined metric. We propose and implement a method for quantifying the amount of potential information enthalpy - the IEP - in a given signal across a range of example signals. We offer a
conjecture of how information enthalpy may be treated by neural systems within a biological framework before showing how it may integrate and offer falsifiability to existing approaches such as the Free Energy Principle. This framework is also positioned in light of the role of neural criticality. Finally, we postulate a testable and falsifiable framework where the distinct mechanisms within each driver interact through a described n-body-inspired model to govern the "motion" of a neural system through a high dimensional state-space. Through these processes, it is proposed that these features form the most fundamental basis of the neural drivers that give rise to the complexity of adaptive behaviors that are commonly called: intelligence.
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All authors Brett J. Kagan, Johnson Zhou, Forough Habibollahi, Valentina Baccetti
Optics · Cross-listed from cond-mat.str-el
Probing and Manipulating Quantum Materials with Strong-field Terahertz and Mid-infrared Radiation
S. J. Li, H. Y. Wu, S. J. Zhang et al. (+1 more)
Emergent phenomena in
quantum materials arise from interactions among different degrees of freedom. Identifying these interactions and establishing their roles in ordered states are central problems in condensed-matter physics and provide a basis for controlling material properties. Many relevant low-energy excitations and gaps lie in the terahertz (THz) and mid-infrared (MIR) range, where intense phase-stable fields can both interrogate nonlinear dynamics and drive selected degrees of freedom far from
equilibrium. This review surveys recent progress in probing and manipulating
quantum materials with strong-field THz and MIR radiation, with emphasis on nonlinear electronic dynamics, collective-mode coupling,
symmetry-sensitive responses and field-induced changes in electronic structure and ordered states. Particular
attention is given to developments enabled by the Synergetic Extreme Condition User Facility (SECUF).
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All authors S. J. Li, H. Y. Wu, S. J. Zhang, Y. T. Li
Plasma Physics
The Richtmyer-Meshkov Instability of Thermal, Isotope, and Species Interfaces in a five-moment multi-fluid plasma
K. C. Tapinou, V. Wheatley, D. Bond et al. (+1 more)
The Richtmyer-Meshkov instability (RMI) results from the impulsive acceleration of a density interface where either it or the acceleration is perturbed. Density interfaces may arise due to a change in gas species, isotope, temperature or a combination of these. We computationally investigate the effect of interface type on the
plasma RMI, which is relevant for a range of applications, including inertial confinement fusion. We simulate the
evolution of single-mode perturbed thermal, species and isotope interfaces in an ideal ion-electron
plasma using the multi-fluid
plasma (MFP) model. We find that in the MFP model, the
evolution of different types of interface differ significantly, in contrast to single-fluid models where they behave similarly if the Atwood number is matched. The thermal and species interfaces produce the most severe response to shock acceleration, experiencing the secondary instabilities and enhanced primary mode growth. The isotope interface
evolution is restrained in comparison to the former cases, resembling the response predicted by single-fluid models. The determining factor in the severity of the MFP RMI is the density ratio across the initial interface in the electron fluid, which is unity for an isotope interface. We observe that as the density ratio across the electron interface decreases, so do the magnitudes of the self-generated fields and consequently the severity of the growth amplification. Generally, the
evolution of the RMI with different types of interface becomes more similar as the level of coupling between the ion and electron fluids is increased, characterised by reducing the
plasma non-dimensional skin depth
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All authors K. C. Tapinou, V. Wheatley, D. Bond, Ingo Jahn
Fluid Dynamics · Cross-listed from cs.LG
Cova-PINN: Cross-Domain Conservation Physics-Informed Neural Network for Fluid-Solid Conjugate Heat Transfer in Complex Geometries
Weizheng Zhang, Xunjie Xie, Hao Pan et al. (+1 more)
Multi-domain physics-informed neural networks (PINNs) flexibly model medium-specific representations to solve fluid–solid conjugate heat transfer (CHT). However, standard multi-domain PINNs enforce governing equations and interface conditions on separately sampled domain supports, which can yield plausible temperature fields but inaccurate end-to-end energy transfer and outlet temperatures. We propose Cova-PINN, a multi-domain PINN framework that aligns conservation support with thermal interaction paths in complex geometries. Cova-PINN jointly optimizes cross-domain composite control-volume balances at the local scale and paired-wall closure at the global exchanger scale. We evaluate Cova-PINN on four triply periodic minimal surface (TPMS) heat exchangers and a geometrically distinct DualMS design against CHT-specific, optimization-oriented, and complex-geometry PINN baselines under a common protocol. Relative to the closest baseline, MUSA-PINN-CHT, Cova-PINN reduces average outlet-temperature and device-level closure errors across the four TPMS
topologies by $37.7\%$ and $60.2\%$, respectively, while also improving full-field and heat-duty accuracy, with consistent gains on DualMS.
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All authors Weizheng Zhang, Xunjie Xie, Hao Pan, Lin Lu