Optics
Spiral metasurface enables tunable directional edge enhancement
Wenli Wang, Yao Hu, Qiusheng Huang et al. (+2 more)
Tunable directional edge enhancement facilitates the acquisition of distinct morphological features from objects, a capability that plays a vital role in enhancing the reliability and safety of autonomous driving systems. However, building a simple, miniature, and switchable directional edge enhancement system remains an urgent challenge. To address this, we propose a compact spiral metasurface capable of achieving tunable vertical and horizontal edge enhancement imaging without requiring a conventional 4f system, relying instead on a single integrated device. This functionality is realized by engineering the metasurface's spiral phase profile and its polarization-dependent response, where the edge enhancement direction is controlled by varying the incident beam's polarization, enabling switching between vertical and horizontal enhancement modes. Simulations demonstrate the metasurface's capability for switchable edge detection of lane markings and barrier contours. Broadband operation is also confirmed through simulation results. Owing to its compactness, switchable functionality, and broadband performance, the proposed spiral metasurface shows significant potential for applications in optical analog computing and autonomous driving.
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All authors Wenli Wang, Yao Hu, Qiusheng Huang, Dan Chen, Qun Hao
Optics
Characterization of Photopolymerized Microscopic Chiral Structures Using Photonic Orbital Angular Momentum
Jing Xu, Rik Strobbe, Yovan de Coene et al. (+2 more)
The controlled fabrication and chiroptical characterization of microscale
chiral structures remain central challenges in photonics, sensing, and metamaterial engineering. Here we demonstrate an accessible, low-cost platform that combines digital micromirror device-enabled maskless photolithography with capillarity-induced self-assembly to produce
polymer chiral microstructures of deterministic handedness, and a
liquid-
crystal spatial light modulator to generate
vortex beams for their characterization via helical dichroism (HD). Using a standard 532 nm
laser, we observe HD signals of approximately 30% for microstructures with a characteristic diameter of about 15 micrometers. Rigorous finite-difference time-domain simulations performed on three-dimensional geometries reconstructed from high-resolution Scanning Electron Microscopy data reproduce the experimental HD spectra and confirm the role of structural handedness in driving the differential orbital angular momentum (OAM) response. Near-mirror-symmetric HD spectra for opposite-handed enantiomers, combined with a vanishing response for achiral controls, establish OAM as a robust and spatially selective
chiral probe at the microscale. Crucially, both fabrication and characterization rely on equipment standard in an optics laboratory, without recourse to femtosecond sources, plasmonic substrates, or costly photoresists. These results open practical pathways toward OAM-driven
chiral sensing, enantioselective detection, and photonic logic devices.
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All authors Jing Xu, Rik Strobbe, Yovan de Coene, Renaud A. L. Vallée, Koen Clays
Applied Physics · Cross-listed from quant-ph
Scalar and Vector Airborne Platform Calibration Using Quantum and Classical Magnetometers and Inertial Sensors
Antonia Hager, Torleiv H. Bryne and Mia Jukić
Airborne magnetometry requires rigorous calibration to isolate geomagnetic signals from sensor errors and platform
magnetic fields. This
magnetic compensation is needed for applications like geophysical exploration and
magnetic anomaly
navigation. The standard approach utilizes a
quantum scalar Optically Pumped Magnetometer (OPM) and a less sensitive fluxgate vector sensor for attitude information. This configuration typically results in a scalar approximation of the platform field. Advancements in high-sensitivity Diamond Nitrogen-Vacancy (NV) vector magnetometers now enable a re-evaluation of the standard hardware configuration and full vector calibration models. We show through rigorous theoretical analysis that scalar calibration models are robust to misalignment. Vector calibration models, however, are intrinsically first-order sensitive to attitude errors, irrespective of the accuracy of the
magnetic field measurements. These errors arise from inaccurate representation of the background field direction in the body frame, and can amplify small orientation errors into noticeable calibration residuals. Using realistic sensor models and flight trajectories, we evaluate different sensor configurations for
magnetic calibration and assess the use of onboard Inertial
Navigation Systems (INS) as an independent attitude reference to enable stable compensation. Our results suggest that
quantum vector magnetometers like NV sensors are not sufficient to solve the attitude bottleneck for airborne vector
magnetic calibration. However, as a single sensor capable of providing both absolute field and directional measurements, they may offer benefits regarding sensor placement, synchronization, and scalar calibration accuracy.
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Accelerator Physics
Low Beta, Normal Conducting Cavities
Lars Groening
The contribution is on issues being especially related to normal conducting cavities operating at non-relativistic beam energies. Various types of cavities are introduced w.r.t. their operation mode, application, advantages, and disadvantages. Special emphasis is put on their production and the challenges along the way from finalized Rf-design up to the operating cavity. This covers the choice of material, production, tolerances,
alignment, cooling, and the demanding task of copper plating. The contribution closes with some remarks on Rf-commissioning and -conditioning.
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Computational Physics · Cross-listed from hep-ex
Geant4 Optical Simulation without C++
Ariestotle Raj Maharjan, Jianchen Li and Jing Liu
The plain text geometry description syntax in Geant4 has been extended to incorporate optical properties for bulk materials and surface interfaces. This extension enables users to configure and execute comprehensive optical simulations without writing C++ code, significantly lowering the learning curve and eliminating the need for frequent recompilation. In this paper, we detail the implementation of the new ":prop" and ":surf" tags and validate them through examples of key optical processes, including Cherenkov radiation, scintillation, Rayleigh scattering, and absorption. Furthermore, we provide a thorough demonstration of configuring complex optical boundaries using the UNIFIED model. These capabilities are contextualized through practical scenarios, showcasing the extension's potential for rapid prototyping and simulation studies.
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Fluid Dynamics
Buffet Alleviation via Linear Stability Adjoint
Rohit Sunil Kanchi, Sicheng He, Eirikur Jonsson et al. (+1 more)
Transonic buffet, self–sustained shock and shear–layer oscillations, imposes hard limits on the cruise envelope of modern transport aircraft, and avoiding it is a primary design driver. State-of-the-art buffet-onset criteria used in design, such as the $\Delta\alpha = 0.1^\circ$ criterion and separation–sensor methods, are empirical surrogates rather than first–principle predictors, and can yield either overly conservative or unsafe designs. Linear stability analysis (LST) predicts buffet onset directly from the spectrum of the linearized operator about the steady base flow, but using it as an aerodynamic shape optimization constraint has been bottlenecked by the cost of differentiating an
eigenvalue with respect to many design variables. In this paper, we develop a coupled adjoint method that efficiently computes the sensitivity of the dominant LST
eigenvalue with respect to a large number of shape design variables, by reusing the steady CFD adjoint within a top and bottom level decomposition of the eigenproblem. We verify the eigensolver and adjoint against the canonical cylinder
vortex–shedding
benchmark, then verify the LST predictions on the OAT15A supercritical airfoil at $M=0.73$, $Re=3.2\times 10^{6}$ against published eigenspectra and against the linear growth phase of a URANS run. Using the resulting gradients, a single-point buffet-constrained drag minimization of the OAT15A achieves a $22.4\%$ drag reduction while satisfying the LST-based buffet constraint. Finally, we present preliminary three-dimensional results on the wing only NASA common research model (CRM) at $M=0.85$, $Re=5\times 10^{6}$, recovering buffet onset at $\alpha \approx 4.0^\circ$ from a sweep of warm–started URANS runs and providing a stepping stone toward three-dimensional buffet-constrained wing optimization with the present adjoint.
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All authors Rohit Sunil Kanchi, Sicheng He, Eirikur Jonsson, Joaquim R. R. A. Martins
Atmospheric and Oceanic Physics · Cross-listed from cs.CE
From Classical to Quantum-Mechanical Data Assimilation: A Comparison between DATO and QMDA
Emanuele Donno, Giovanni Conti, Paolo Oddo et al. (+3 more)
Data assimilation provides a systematic framework for combining dynamical models with partial and noisy observations to infer the evolving state of a system. In this work, we undertake a comparative study of Data Assimilation with Transfer Operators (DATO) and
Quantum Mechanical Data Assimilation (QMDA), focusing on their mathematical formulation, algorithmic structure, and empirical performance. Both methods are first cast within a common operator-theoretic framework, which makes it possible to compare, on a unified basis, their representations of uncertainty, forecast propagation, and assimilation updates. We then analyse their principal similarities and differences with respect to state-space structure, update mechanisms, structural preservation properties, and computational cost. To complement the theoretical analysis, we assess both approaches on
benchmark dynamical systems across a range of observational settings, including noisy, sparse, and partially observed regimes. Our results show that, despite their shared operator-theoretic motivation, DATO and QMDA embody substantially different assimilation paradigms, leading to distinct advantages and limitations in terms of interpretability, robustness, and scalability. The present study helps delineate the regimes in which each framework is most effective and offers broader insight into the design of operator-based methodologies for data assimilation.
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All authors Emanuele Donno, Giovanni Conti, Paolo Oddo, Silvio Gualdi, Luca Mainetti, Giovanni Aloisio
Fluid Dynamics · Cross-listed from cond-mat.soft
Understanding the Dynamics of Evaporation-Driven Colloidal Self-Assembly
Junyu Yang, Abhinav Naga, Xitong Zhang et al. (+1 more)
Complex colloidal cluster morphologies are desirable for the fabrication of advanced materials, such as photonic
crystals and meta-materials, and can be formed through evaporation-driven packing. By coupling
lattice Boltzmann and discrete element methods, here we elucidate the rich interplay between fluid and particle dynamics during evaporation-driven self-assembly of spherical colloidal particles. We construct a regime diagram for a wide range of evaporation rates, interparticle friction coefficients, and particle numbers, identifying parameter regimes for open, closed, and minimal moment of inertia cluster configurations. Analyzing the competition between capillary, hydrodynamic, normal, and friction forces, we show that interparticle friction can exert a disproportionately strong influence on the final packing outcome despite being considerably smaller in magnitude than other forces at play. Our simulation results further highlight the potential for tuning colloidal cluster configurations via their dynamic trajectories.
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All authors Junyu Yang, Abhinav Naga, Xitong Zhang, Halim Kusumaatmaja
Optics
Band-Selective LDOS Engineering of Yb/Er Upconversion: an Electromagnetic-Kinetic Diagnostic Framework
Yuxiang Zhang, Mayte Gómez-Castaño, Agustín Mihi et al. (+3 more)
A persistent challenge in plasmonic upconversion is decoupling pump-field enhancement from emission-side local-density-of-optical-states (LDOS) engineering to achieve selective band manipulation. Here, we show that a corrugated SU8/Au/Al2O3 grating coated with a NaYF4:Yb/Er upconversion nanoparticle (UCNP) monolayer realizes a truly band-selective platform. A broad plasmonic resonance near 670 nm modulates the red Er 3 + 3+ decay rate by $\pm$15% as a function of the Al2O3 spacer thickness, while leaving the green transition experimentally invariant (< 1% change). Simultaneously, the 980 nm pump field is monotonically suppressed below free-space levels, ensuring that steady-state and time-resolved observables cleanly probe the emission-side LDOS without pump interference. We analyze this system using a coupled electromagnetic-kinetic framework that integrates finite-difference time-domain (FDTD) calculations of Purcell factors and pump fields with a six-level Yb/Er rate-equation model. The framework quantitatively reproduces the 670 nm plasmonic resonance, the red-band decay-rate modulation, and the monotonic decrease of the green/red intensity ratio. Crucially, the model serves as a powerful diagnostic tool: it overpredicts a green-band rate reduction, but systematic parametric testing rules out
geometric (apex smoothing) and material (grain-boundary damping, interband loss) imperfections as the cause. Instead, it isolates the residual discrepancy to measurement-versus-model factors (finite-aperture angular averaging) and missing non-radiative kinetic channels, establishing a clear roadmap for the rational design and validation of future plasmonic-UCNP architectures.
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All authors Yuxiang Zhang, Mayte Gómez-Castaño, Agustín Mihi, Serge Ravaine, Xiaogang Liu, Renaud A. L. Vallée
Applied Physics · Cross-listed from cond-mat.mtrl-sci
A Two-Step Chemical Vapor Deposition Process for the Synthesis of an Ir(111)/Borophene/2D-Hexagonal Boron Nitride Heterostructure by Intrinsic Segregation
Marko A. Kriegel, Karim M. Omambac, Smruti R. Mohanty et al. (+10 more)
We report on a two-step ultrahigh
vacuum chemical vapor deposition synthesis of a vertical Ir(111)/borophene/hexagonal boron nitride
heterostructure, using borazine as a single-source precursor. The process takes advantage of the finite solubility of boron in Ir: low precursor pressure at high temperature first establishes a boron reservoir in the near-surface region of the substrate, whereas subsequent growth at higher precursor pressure promotes the formation of a closed hexagonal boron nitride monolayer. During cooldown, the reduced boron solubility drives segregation to the surface, resulting in the formation of a borophene monolayer beneath the hexagonal boron nitride overlayer. The
heterostructure, with micron sized grains, homogeneously covers the entire Ir substrate. The study is performed by complementary spot profile analysis low-energy electron diffraction, low-energy electron microscopy, and scanning tunneling microscopy measurements. This intrinsic segregation-assisted growth concept provides a promising route toward scalable synthesis of high-quality, vertical
heterostructures of two-dimensional materials.
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All authors Marko A. Kriegel, Karim M. Omambac, Smruti R. Mohanty, Tobias Hartl, Stefan Schulte, Niels Ganser, Pascal Dreher, Alexandra Rödl, Steffen Franzka, Germán Sciaini, Thomas Michely, Frank-J. Meyer zu Heringdorf, Michael Horn-von Hoegen
Optics
Unraveling the Defect Physics of SiC Micropipe Sidewalls by Non-Line-of-Sight Confocal Spectromicroscopy: Amphoteric Giant Traps
Irwan Saleh Kurniawan, Russel Cruz Sevilla, Ruth Jeane Soebroto et al. (+6 more)
Micropipes are among the most detrimental defects in SiC wafer and are closely linked to catastrophic device failure. However, the microscopic defect nature of their internal sidewalls and the mechanism of the associated leakage current remain poorly understood, because their high-aspect-ratio geometry severely restricts direct optical probing. Here, we develop a non-line-of-sight confocal multiple-reflection spectromicroscopy technique combined with direct defect photoionization to unravel the defect physics of micropipe sidewalls. We show that these sidewalls host a high density of donor-like and acceptor-like deep-level states, giving rise to ultrabroad emission bands composed of intrinsic DAP-like recombination and detrapping-mediated free-to-bound transitions. Unlike conventional defect luminescence, the DAP-like emission remains dominant even at room temperature across all excitation powers. This behavior is attributed to rapid carrier capture by the sidewall defects, as evidenced by fast-rising and nanosecond-scale decay dynamics, along with coupled carrier kinetics. These results suggest that micropipe sidewalls can serve as extended amphoteric
giant traps and carrier reservoirs, facilitating leakage current through trap-assisted transport. Our work provides a nondestructive optical approach for directly probing high-aspect-ratio extended defects and offers deep mechanistic insight into their defect physics and leakage mechanisms.
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All authors Irwan Saleh Kurniawan, Russel Cruz Sevilla, Ruth Jeane Soebroto, Hsiu-Ying Huang, Hsiu-Ming Hsu, Ji-Lin Shen, Sheng Hsiung Chang, Wen-Chung Li, Chi-Tsu Yuan
Optics
Emergence of Localized Surface Plasmons in Unpatterned Hyperdoped Polycrystalline Silicon
Mohamad Bahsoun, Jesse Groenen, Gonzague Agez et al. (+7 more)
The ability to engineer localized surface plasmon resonances at large scale usually relies on precise nanoscale patterning. Here, we demonstrate that mid-infrared plasmonic responses can instead emerge in unpatterned polysilicon films composed of nanometric (5-50 nm) grains, challenging established design paradigms and eliminating the need for external nanostructuring. Using tailored out-of-
equilibrium annealing conditions, we show that hyperdoped polysilicon layers exhibit enhanced light-matter interactions that can be tuned across the mid-infrared range. By combining advanced electron microscopy, infrared spectroscopy and finite-difference time-domain electrodynamic simulations, we demonstrate that these remarkable optical properties originate from naturally formed metal-dielectric interfaces at grain boundaries, which support localized surface plasmon resonances. Importantly, this result is universal and can be extended to any doped
semiconductor system, regardless of the synthesis technique, provided that the grain size remains in the nanometric range. This work opens up a new field in plasmonics centered on polycrystalline
semiconductors, paving the way for cost-effective systems that are fully compatible with microelectronic and photovoltaic technologies, and capable of significantly reshaping light-matter interactions in the infrared range.
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All authors Mohamad Bahsoun, Jesse Groenen, Gonzague Agez, Sébastien Joulié, Cécile Marcelot, Robin Cours, Sébastien Kerdiles, Mathieu Opprecht, Caroline Bonafos, Jean-Marie Poumirol
Geophysics · Cross-listed from astro-ph.EP
Earth and Mars interior structures set by re-melting of the first solid mantle
Antonio Manjón-Cabeza Córdoba, Maxim D. Ballmer and Oliver Shorttle
Magma ocean crystallisation sets up the early structure and long-term
evolution of terrestrial
planets. Recent seismic evidence signals the presence of a silicate layer at the base of Mars' mantle. Magma-ocean crystallisation and subsequent overturn has been invoked as a hypothesis for this layer's origin. However, while a magma ocean existed in both Earth and Mars, there is no seismic evidence for a basal layer in present-day Earth. In this study, we apply a parameterized-convection model to study whether the effect of partial melting in the growing mantle on overlying magma ocean composition can explain this discrepancy. Melts from the mantle buffer the crystallising magma ocean, limiting progressive differentiation, iron enrichment and the density anomaly of the overturned layer. This buffering is more efficient for larger
planets with more vigorous mantle convection and for
planets that are originally less enriched in iron. Consequently, a shallow magma ocean is more iron enriched and denser on Mars than on Earth, providing an explanation for the Mars-Earth difference in present-day structure of the mantle. We also predict a dichotomy in terrestrial-
exoplanet interior structures, with a population with small, stratified mantles and another with large, mostly-homogeneous mantles.
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Fluid Dynamics
Modelling Farm-to-Farm Interaction Using a Fast Linearised Numerical Approach
Alexia Everley, Hossein A. Kafiabad and Majid Bastankhah
This paper presents a computationally efficient, linearised numerical method for modelling aerodynamic interactions between wind farms. The linearised two-dimensional incompressible equations are solved using
Fourier transforms in the horizontal direction and finite-difference discretisation in the vertical. Model predictions are validated against large-eddy simulation (LES) data, focusing on a tandem wind farm configuration where a downstream wind farm operates within the wake of an upstream array. A parametric study is then conducted to examine the impact of this wake on the performance of the downstream farm across a range of inter-farm distances and hub-height ratios. We demonstrate that the upward vertical displacement of these wakes is driven by asymmetric turbulent entrainment caused by the farm's proximity to the ground, which restricts downward wake expansion. Consequently, the results suggest that, due to this upward wake displacement, downstream wind farms with higher hub heights may be more strongly affected by upstream farms than those with lower hub heights.
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Applied Physics · Cross-listed from cond-mat.mes-hall
Spin-wave bandgap engineering via mode hybridization in dipolar-coupled YIG film/CoFeB nanodisk magnonic crystals
Junyoung Hyun, Krzysztof Szulc, Mateusz Zelent et al. (+5 more)
We investigate
spin-wave transport in hybrid two-dimensional magnonic
crystals comprising a low-damping yttrium iron garnet (YIG) film coupled to a periodic array of CoFeB nanodisks. Using propagating
spin-wave spectroscopy, super-Nyquist magneto-optical Kerr effect microscopy, and micromagnetic simulations, we demonstrate the formation of pronounced and tunable bandgaps that do not originate from conventional Bragg scattering. Instead, these gaps arise from hybridization between the fundamental magnonic-
crystal mode and in-plane transverse standing modes induced by the periodic nanodisk array. The spectral position and width of these gaps are controlled by
geometric parameters and by the
magnetic state of the nanodisks, including their
vortex configuration, which governs both static and dynamic dipolar coupling. For larger
lattice periods, additional gaps emerge through hybridization with modes quantized both transverse and parallel to the
spin-wave propagation direction, reflecting dispersion folding in two dimensions. Our results establish mode hybridization as a versatile mechanism for engineering
spin-wave band structures beyond the constraints of Bragg scattering and provide a pathway toward reconfigurable magnonic devices based on dipolar-coupled hybrid architectures.
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All authors Junyoung Hyun, Krzysztof Szulc, Mateusz Zelent, Nikolai Kuznetsov, Lukáš Flajšman, Maciej Krawczyk, Paweł Gruszecki, Sebastiaan van Dijken
Chemical Physics
Multistate Coupled Diabatic Neural Network potential for the quantum non-adiabatic Photofragmentation of CH$_2^+$
Pablo del Mazo-Sevillano, Susana Gomez-Carrasco, Alfredo Aguado et al. (+1 more)
Tracking the complex non-adiabatic transitions in far-ultraviolet photodissociation demands highly accurate diabatic potential energy
matrices (PEMs) across numerous excited states. To address this, we introduce a fully automated diabatization method that leverages artificial neural networks to fit PEMs. Our approach divides the PEM into a physically grounded zeroth-order diagonal term, which is then corrected by a neural network
matrix to capture electronic couplings. By enforcing
symmetry constraints on off-diagonal elements and sharing degenerate diabatic states between the $A'$ and $A''$ irreducible representations, the { diabatization} process becomes completely automatic. We validate this method using time-dependent wavepacket calculations to simulate the photodissociation of CH$_2^+$, incorporating relevant states up to $\approx 13.6$~eV. Finally, we compute partial cross-sections for all fragmentation channels – including total and partial fragmentation yielding \ce{CH+}, \ce{CH}, \ce{H2}, and \ce{H2+} diatoms – revealing a notably high cross-section for the formation of the \ce{CH} radical.
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All authors Pablo del Mazo-Sevillano, Susana Gomez-Carrasco, Alfredo Aguado, Octavio Roncero
Physics and Society
Lithium enrichment threatens to curb fusion deployment
Samuel H. Ward, Richard J. Pearson, Thomas B. Scott et al. (+1 more)
The impact of lithium isotopic enrichment on the global deployment of
nuclear fusion energy is analysed. Lithium - the 6Li isotope in particular - is essentially one of two elemental fuels required by fusion reactors for tritium breeding. Whilst variable consumption of lithium is low enough to present negligible cost, it is instead the large stored inventory volume (50-100 tonnes) and its required enrichment that compound to significantly drive capital costs. These costs are driven by the inefficiency of the tritium breeding process, making this challenge fundamental to almost all fusion power plant concepts. Financing would further compound these effects, making lithium fusion fuels more akin to an upfront capital expenditure than operational expenditure. Other potential barriers to fusion deployment created by lithium are also discussed: enrichment technologies of today are shown to be too expensive, not scalable, and environmentally risky, and highly enriched 6Li is a controlled substance. Mitigating actions include: developing alternative enrichment technologies that are affordable, scalable, and do not rely on mercury; incorporating lithium enrichment as an explicit cost driver in reactor design processes, producing more compact reactors with smaller lithium inventories; establishing distinct enrichment levels to enable supply chain monitoring for misuse; and the most radical solution: breeding blankets that use natural, unenriched lithium. These actions may impact tritium breeding capabilities, which calls for an urgent re-assessment of the tritium breeding paradigm. Whatever solution is sought, lithium supply is a mission-critical issue that needs urgently addressing.
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All authors Samuel H. Ward, Richard J. Pearson, Thomas B. Scott, Niek J. Lopes Cardozo
Instrumentation and Detectors
Machine learning inference of fission yields from gamma spectroscopy for very low-yield nuclear test verification
Julien de Troullioud de Lanversin, Jiehui Li, Christopher Fichtlscherer et al. (+2 more)
Very low-yield
nuclear tests pose a major verification challenge for the zero-yield standard of the Comprehensive
Nuclear-Test-Ban Treaty (CTBT). The zero-yield standard prohibits any explosive experiment that produces a self-sustaining fission chain reaction while allowing subcritical experiments. Previous research shows that on-site gamma spectroscopy of post-test debris provides useful insight into the criticality level, although it remains heavily dependent on knowledge of certain experimental settings. Here, we adopt a new approach whereby machine learning models are trained on simulated gamma spectroscopy data to infer the fission yield of a
nuclear very low-yield test. Using high-fidelity 3D Monte Carlo particle transport simulations, we generated gamma spectra measured outside containment vessels after very low-yield tests for 66 million representative scenarios. From these spectra, we extracted 82 fission-product-to-plutonium-239 peak ratios, then trained ML models for two tasks: (1) binary classification of whether a test exceeded a chosen yield threshold, and (2) regression to estimate the actual yield. We find that XGBoost performs best on the classification task across the most policy-relevant yield range. The classifier achieves high accuracy even for yields near the chosen threshold (e.g., >95% for yields +-100 g around a threshold at 1 kg TNT), and the regressor presents a mean absolute relative error of 12.4% for measurements taken a month to a year after the test. These results demonstrate that using machine learning to infer the yield of a past very low-yield
nuclear test from gamma spectroscopy data is feasible and accurate. This approach can support efforts to establish a robust verification protocol for the zero-yield standard and could pave the way for a future yield threshold-based verification regime that is both technically feasible and politically viable.
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All authors Julien de Troullioud de Lanversin, Jiehui Li, Christopher Fichtlscherer, Dongdong She, Moritz Kütt
Optics
Reconfigurable and cascaded logic gates using dual-input multilayered heater nanocryotrons
Behnoosh Babaghorbani, M. Yu. Mikhailov, Hui Wang et al. (+3 more)
Superconducting electronics have emerged as a promising platform for advanced information processing, offering unique opportunities for on chip computation and signal manipulation at cryogenic temperatures. These devices hold particular potential in applications ranging from
quantum computing to high sensitivity
magnetic sensing, where integrated logic and scalable
circuit architectures are essential for performing complex computational and signal-processing tasks. In this work, we present a dual-input multilayered heater nanocryotron (hTron) that introduces both multi input functionality and reconfigurable logic capability within a single device. This capability represents a step forward toward realizing more complex computational architectures. In addition, we demonstrate that these devices can, in principle, drive one another and potentially be integrated on a larger scale. Furthermore, the inherent reconfigurability of the demonstrated device allows for dynamic switching between logic operations without requiring additional components which reduces
circuit area and simplifies cryogenic and biasing requirements, making the design highly suitable for scalable superconducting computing systems.
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All authors Behnoosh Babaghorbani, M. Yu. Mikhailov, Hui Wang, Thomas Descamps, Val Zwiller, Iman Esmaeil Zadeh
Chemical Physics
On Electropolymerized Fingerprints and their Potential for Identification and Encryption
Antoine Baron, Luc Brulin, Corentin Scholaert et al. (+3 more)
While human technology is ruled by determinism, biological systems exploit a subtle balance of control and stochasticity. This balance, evident in the morphogenesis of textural patterns imprinted on leaves, fur or skin can help hierarchize organisms both as a representative of their species and as unique individuals. In this study, we identified that, by exploiting electrochemistry, it is possible to generate such versatile but specific textures, to imprint patterns of a conducting
polymer on a conducting substrate. It is shown that the 1D morphogenesis of conducting
polymer dendrites on wires translates, on 2D surfaces, as highly heterogeneous coatings of dark spots, rosettes or marbled patterns. Despite their inherent stochasticity, these patterns are characteristic of the physical conditions they grew in, and particularly of the chemical content of the electroactive solution used for their electropolymerization. A statistical study demonstrates that these patterns could be used as fingerprints to physically tag the identity of a solution within a specific class. By the identification of a new electrochemical process which allows generating physical fingerprints with optical, electrical and chemical contrast on an electrode, this research paves the way toward a disruptive low-cost technology which could allow any end-user to generate personal tags on a glass slide or on a micro-chip, to engrave physically-encrypted personal information for various applications.
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All authors Antoine Baron, Luc Brulin, Corentin Scholaert, Yannick Coffinier, Fabien Alibart, Sébastien Pecqueur
Instrumentation and Detectors
Stability of Charge Collection Efficiency in a Novel Graphene-Optimized Silicon Carbide Detector Under 160 keV X-Ray Irradiation
Yingjie Huang, Congcong Wang, Jingxuan He et al. (+4 more)
A novel
graphene-optimized silicon carbide PIN detector was fabricated. Its electrical properties, charge collection performance and signal rise time were evaluated under non-irradiated conditions and under X-ray irradiation with an energy of 160 keV at doses of 0.1 MGy and 1 MGy. The leakage currents of the detectors under non-irradiated, 0.1 MGy, and 1 MGy irradiation conditions are approximately 1.45e-10 A, 1.51e-10 A, and 1.57e-10 A, respectively. The effective doping concentration of the detector is approximately 8.08e13 cm^-3 before and after irradiation, with no significant change. The rise times of the signals from alpha particles signal detected by the detector under unirradiated, 0.1 MGy, and 1 MGy X-ray irradiation conditions are 336 ps, 368 ps, and 387 ps, respectively. The rise times of the beta particles signal detected by the detector under unirradiated, 0.1 MGy, and 1 MGy X-ray irradiation conditions are 342 ps, 375 ps, and 398 ps, respectively. After 0.1 MGy and 1 MGy X-ray irradiation, the charge collection efficiencies (CCEs) of the detector for alpha particles are 97.2% and 90.0%, respectively; for beta particles, they are 100.0% and 97.0%, respectively. Experiments confirm that 160 keV X-ray irradiation may not cause significant displacement damage in the 4H-SiC, and the minor performance degradation may be attributed to ionization induced changes in the
graphene electrode. The detector exhibits excellent charge collection performance and fast time response. These results demonstrate stable performance under extreme X-ray exposure, highlighting the detector's potential for radiation-hard applications in high-energy physics, space missions, and
nuclear reactor monitoring.
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All authors Yingjie Huang, Congcong Wang, Jingxuan He, Yi Zhan, Zhenyu Jiang, Xiyuan Zhang, Xin Shi
Medical Physics
A Physics-Constrained Learning Framework for Wave Propagation in Complex Poroelastic Multilayered Media
Ya Gao, Yifan Wang, Yiming Chen et al. (+5 more)
Wave propagation through complex poroelastic multilayered media is difficult to model and invert because pronounced heterogeneity, scattering, mode conversion and fluid-solid coupling jointly distort acoustic signals during propagation. Here we present Physics-Constrained Learning for Complex Multilayered Media (PCL-CMM), a general framework that integrates Biot's poroelastic theory with the elastic wave equation to bridge the gap between physically rigorous wave modelling and data-driven learning. PCL-CMM constructs a high-fidelity digital twin that dynamically computes an effective acoustic stiffness tensor for forward wave modelling and incorporates the resulting physical constraint as a loss term to regularize the training of deep neural networks. We demonstrate PCL-CMM on transcranial photoacoustic imaging, where skull-induced acoustic distortions severely degrade image formation. Across simulations and ex vivo experiments, PCL-CMM effectively compensates for these distortions and improves SSIM by more than 0.06 compared with purely data-driven neural networks. This work establishes a physics-constrained learning framework for acoustic wave modelling in complex poroelastic multilayered media.
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All authors Ya Gao, Yifan Wang, Yiming Chen, Haohan Sun, Shoukun Lyu, Junmei Cao, Weijiang Xu, Qian Cheng
Optics
The Nonreciprocal Mie-surfaces
Dheeraj Pratap
Hemispherical amorphous silicon nanoparticles exhibit asymmetric optical scattering for forward illumination (base-to-apex) and backward illumination (apex-to-base). There exists an anapole mode only for backward propagation, not for forward. Due to the anapole, light is allowed to scatter maximally along the forward direction, and not in the backward direction. A structured surface obtained by repeating hemispheres in a square grid in air exhibits nonreciprocal reflection and transmission for light propagating through it. This nonreciprocity only depends on the diameter of the hemisphere, not on the periodicity. The same surface on a glass substrate causes a minor spectral
redshift in the nonreciprocity. Here, the individual materials are Lorentz reciprocal, but the current nonreciprocity is due to interference. The current nonreciprocity is purely based on anapole of Mie scattering; therefore, the surface is termed as “Nonreciprocal Mie-surface”. Such surfaces could be used for the applications of passive linear nonreciprocal photonic devices.
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Computational Physics · Cross-listed from cs.LG
From Video-to-PDE: Data-Driven Discovery of Nonlinear Dye Plume Dynamics
Cesar Acosta-Minoli and Sayantan Sarkar
Inferring continuum models directly from
video is hampered by two facts: the recorded field is uncalibrated image intensity rather than a physical state, and direct numerical differentiation of noisy frames is unstable. We develop a
video-to-PDE pipeline that converts grayscale recordings of an ink plume into a normalised scalar field $u(x,y,t)$, isolates a bulk drift $\mathbf{v}(t)$ from intrinsic spreading via the intensity-weighted centroid, and identifies an effective transport law by weak-form sparse regression. Conditioning, threshold-sweep and random-centre diagnostics show that overcomplete libraries are strongly collinear; the search is therefore restricted to compact gradient-based libraries. Coefficients are refined by an inverse physics-informed network and recalibrated against forward rollouts, with a chronological block bootstrap quantifying uncertainty. The selected reduced model $u_t+\mathbf v(t)\!\cdot\!\nabla u = 9.005\,|\nabla u|^{2}+0.666\,\Delta u$ outperforms advection–
diffusion baselines on held-out frames, retains a positive
Laplacian coefficient, and admits a Cole–
Hopf reduction to a linear advection–
diffusion equation. The framework demonstrates that uncalibrated visual data can yield compact, predictive and structurally interpretable continuum models when discovery, calibration and uncertainty are treated as distinct stages.
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Medical Physics
Development and Validation of Patient-Specific Monte Carlo Dosimetry for Synchrotron Breast Phase-Contrast CT
Amir Entezam, Ashkan Pakzad, Christopher J. Hall et al. (+11 more)
This study develops and validates a patient-specific Monte Carlo (MC) dosimetry framework for propagation-based phase-contrast breast CT (BCT) at the Imaging and Medical Beamline (IMBL), ANSTO Australian Synchrotron, for accurate mean glandular dose (MGD) estimation. BCT provides 3D imaging without breast compression, improving comfort and visualization of internal structures for cancer detection. Propagation-based phase contrast improves soft-tissue contrast at equal or lower dose than conventional systems. Accurate dosimetry remains essential for safety and optimisation. Most MC-based MGD studies use non-patient-specific phantoms that ignore anatomical variability, while existing patient-specific methods lack a unified framework. Here, a voxel-based MC framework using EGSnrc was implemented to compute MGD in realistic anthropomorphic breast phantoms derived from synchrotron BCT images. IMBL beam characteristics were used as source inputs. Homogeneous phantoms were also generated to compute air Kerma to MGD conversion coefficients (DgN) for comparison with heterogeneous models. Simulations covered breast height, skin thickness, and
photon energies (28 to 38 keV). Results show MGD depends strongly on anatomy and energy. Higher glandular density reduces MGD, while larger breast volume increases dose. A 2 mm increase in skin thickness reduces MGD by 10%. Differences between heterogeneous and homogeneous phantoms show variations in DgN, highlighting the need for anatomical realism. The framework provides a robust basis for patient-specific dosimetry in synchrotron phase-contrast BCT, enabling precise MGD estimation and supporting safe, optimised clinical imaging. This supports improved protocol design and contributes to standardised patient-specific dosimetry for clinical translation across varying breast anatomies and imaging conditions within synchrotron BCT applications.
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All authors Amir Entezam, Ashkan Pakzad, Christopher J. Hall, Anton Maksimenko, Matthew John Cameron, Adam Round, Mojtaba Hoseini-Ghahfarokhi, Seyedamir T. Taba, Yakov I. Nesterets, Daniel Hausermann, Magdalena Bazalova-Carter, Patrick C. Brennan, Timur E. Gureyev, Harry M. Quiney
Chemical Physics
Angular Gausslets
Steven R. White
Gausslets are one of the few basis constructions for electronic structure that combine locality, orthonormality, variable resolution, and an accurate diagonal approximation for the electron-electron interaction, but the original construction is tied to one dimension. Radial gausslets extended this idea to atoms while leaving the angular degrees of freedom in spherical harmonics, so the atomic interaction remained only partially diagonal in the combined basis. Here we introduce generalized gausslets on the sphere and combine them shell by shell with radial gausslets to form an atom-centered basis in which the electron-electron interaction takes a two-index integral-diagonal form. The angular basis starts from localized spherical Gaussians and uses injection to make a low-$\ell$ spherical-harmonic subspace exact. Tests of the kinetic spectrum, low-$\ell$ Coulomb
matrix elements, spherium, first-row Hartree–Fock calculations, and He exact diagonalization show systematic convergence with increasing angular resolution. We also develop DMRG methods for this basis, including compact MPOs, correlated small-space starting states, Givens-rotation transfers between nearby angular sizes, and embedded sampled variance extrapolation (ESVE). We show that this combination of ingredients can be used to solve the Be atom, with extrapolations in the number of angular functions but with fixed radial resolution, to within about 0.1 mH of the complete basis set limit exact energy. This shows that DMRG calculations of first row atoms which include both static and accurate dynamic correlation on the same footing are feasible.
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Computational Physics
CDFCI: High-Performance Parallel Software for Quantum Many-Body Eigenvalue Problems
Yuejia Zhang, Zhe Wang, Jianfeng Lu et al. (+1 more)
CDFCI is a shared-
memory parallel numerical program for computing low-lying eigenpairs of large-scale, non-relativistic fermionic
Hamiltonians. The software is designed to handle a broad class of many-body
quantum models, including both ab initio electronic structure
Hamiltonians and
lattice-based
Hamiltonians arising in condensed matter physics. CDFCI combines an efficient coordinate-descent-based selected configuration interaction
algorithm with dedicated parallelization strategies, achieving high performance on modern multi-core architectures.
Benchmark results on representative
quantum chemistry and condensed matter test cases demonstrate that CDFCI attains state-of-the-art accuracy with competitive performance compared to established selected configuration interaction (such as CIPSI or SHCI) and DMRG implementations. The software is open-source, extensively documented, and provides a Python interface for seamless integration with PySCF and other many-body simulation workflows.
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All authors Yuejia Zhang, Zhe Wang, Jianfeng Lu, Yingzhou Li
Biological Physics · Cross-listed from cond-mat.soft
Loop Extrusion Reversal by Condensin Motor is Mediated by Catch Bonds
Atreya Dey, Guang Shi, Ryota Takaki et al. (+1 more)
Structural Maintenance Complexes (SMC) are energy consuming motors that are important in folding the genome by loop extrusion (LE) in all stages of the
cell cycle. Single molecule
magnetic tweezer pulling experiments have revealed that condensin, a member of the SMC family involved in mitosis, takes occasional backward steps, thus coughing up the gains in the length of the extruded loop. To reveal the mechanism of the forward and backward steps simultaneously, we developed a theory using the
stochastic kinetic model and the scrunching mechanism for LE. The calculations quantitatively account for the measured force-dependent step size and dwell time distributions in both the directions. By postulating the existence of an intermediate state in the ATP-driven cycle that is poised to take a forward or a backward step, we predict that its lifetime increases as the external mechanical force increases till a critical value and subsequently decreases at higher forces. The surprising finding of lifetime increase in an active motor, at sub-piconewton forces, is the characteristic of catch bonds, known in force-induced rupture of several passive
protein complexes. The identification of catch bond-like states in condensin not only expands our understanding of LE but also highlights the significance of mechanical forces in regulating genome organization.
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All authors Atreya Dey, Guang Shi, Ryota Takaki, D. Thirumalai
Applied Physics · Cross-listed from math.DS
Programming sequential deployment of origami via kinematic transition fronts
Rinki Imada and Tomohiro Tachi
Propagating transition fronts, in which local interactions sequentially trigger state changes, are widely observed across natural, biological, and engineered systems. While such propagation has been engineered using energy-driven instabilities, front propagation governed purely by
geometric constraints remains underexplored and lacks a general design framework. In particular, how to program sequential deployment in origami through such kinematic propagation remains an open challenge. Here, we develop a systematic design framework for kinematic transition fronts based on their correspondence with heteroclinic orbits in discrete dynamical systems. Focusing on strips of developable and flat-foldable degree-4 origami vertices, we show that asymmetric coupling between adjacent creases produces nonlinear recurrence relations whose composition generically gives rise to heteroclinic orbits connecting developed and flat-folded states, enabling domino-like sequential deployment. We further show that macroscopic shape can be programmed independently of propagation behavior by exploiting invariances in the recurrence relation, and illustrate the approach through a representative thick-panel origami prototype. These results enable programmable sequential deployment in origami via transition fronts, while also establishing a general framework for kinematic transition fronts in geometrically constrained systems.
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Plasma Physics · Cross-listed from astro-ph.SR
Nonlinear steepening of a fast magnetoacoustic wave in the vicinity of a coronal magnetic null point
Yu Zhong, Valery M. Nakariakov, Mariana Cécere et al. (+1 more)
The interaction of a fast magnetoacoustic wave with a
magnetic null point is studied in the context of the sympathetic
flare phenomenon.
Attention is paid to steepening the wave caused by the finite-amplitude effects in a non-uniform
plasma environment. The null point is modelled by a potential
magnetic configuration without a guiding field. The
equilibrium plasma density and temperature are taken to be constant. The fast wave is excited by an impulsive point source outside the distance at which the local Alfvén and sound speeds are equal to each other. The incoming fast wave approaches the null point along the bisector of the
magnetic configuration, i.e., across the local field. The fast-speed non-uniformity around the null point causes the refraction of the incident fast wave. However, the segment of the incoming wave, which approaches the null point is locally plane. The decrease in the fast speed towards the null point amplifies the nonlinear deformation of the incoming wave. Hence, the fast wave can become subject to nonlinear dissipation at a distance from the null point and not reach it.
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All authors Yu Zhong, Valery M. Nakariakov, Mariana Cécere, Andrea Costa