Plasma Physics · Cross-listed from cond-mat.mtrl-sci
Electronic-Entropy-Driven Phase Transitions in Compressed Iron Oxides
S. Azadi, S.M. Vinko, C. Crepisson et al. (+3 more)
Electronic
entropy is usually treated as a secondary correction to structural stability, but under strong electronic excitation it can become a primary thermodynamic driving force. Here we show that electronic
entropy can drive both polymorphic and stoichiometric phase transformations in compressed iron oxides. Using finite-temperature density functional theory, we calculate the electronic-temperature-dependent Gibbs free energies of Fe$_2$O, FeO, Fe$_4$O$_5$, Fe$_3$O$_4$, and multiple Fe$_2$O$_3$ polymorphs, including $\alpha$-, $\iota$-, $\zeta$-, $\eta$-, and $\theta$-Fe$_2$O$_3$, over the pressure range 60–260 GPa. At 60-140 GPa, electronic excitation mainly reorganizes the relative stability of Fe$_2$O$_3$ polymorphs, driving transitions from $\iota$-Fe$_2$O$_3$ to $\eta$-Fe$_2$O$_3$. At 180 GPa, the free-energy landscape becomes strongly competitive as FeO is stabilized over an intermediate range of electronic temperature, while $\eta$-Fe$_2$O$_3$ becomes favourable at higher T. At 220-260 GPa, the lowest-free-energy phase at low T is the Fe-rich compound Fe$_2$O, but increasing electronic temperature stabilizes FeO. These results demonstrate that electronic
entropy can control not only the relative stability of
crystal structures at fixed composition, but also the competition between different iron-oxide stoichiometries. The predicted electronic-
entropy-driven phase boundaries provide a route to nonthermal structural transformations in ultrafast and high-energy-density experiments.
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All authors S. Azadi, S.M. Vinko, C. Crepisson, A. Principi, T.D. Kuehne, M.S. Bahramy
Computational Physics
A subcell-refined entropy-residual-driven limiting strategy for high-order discontinuous Galerkin methods
Geng Liang, Rui Wang, Junjie Wang et al. (+3 more)
Fine-grained, subcell-level dissipation control is essential for achieving robust high-order discontinuous Galerkin (DG) simulations of nonlinear
hyperbolic systems in under-resolved regimes while preserving accuracy. This paper proposes a subcell-refined
entropy-residual-driven limiting strategy for DG on Legendre-Gauss-Lobatto nodes. The limiter introduces only nearest-neighbor pairwise dissipation within each element, with closed-form coefficients that supply the minimal dissipation required to restore the element
entropy inequality. The strategy is a diagonal, locally stable approximation of classical
entropy-stable methods, and a generalized subcell framework reveals split-form DG and residual-distribution-based
entropy correction schemes as particular choices of the limiting coefficients. For the Euler equations, a physically consistent jump operator separately models thermal and shear
entropy production while preserving velocity and pressure
equilibrium; a subcell refinement of the Zhang-Shu positivity limiter ensures pointwise positivity. Extensive numerical tests confirm that the scheme maintains optimal high-order accuracy, strictly enforces
entropy dissipation, and significantly reduces the difficulty of a posteriori positivity-preserving procedures.
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All authors Geng Liang, Rui Wang, Junjie Wang, Feng Wang, Xinlong Feng, Hui Xu
Computational Physics · Cross-listed from math.NA
A Discretely Entropy Conserving/Stable Flux Reconstruction Scheme via Hybridized Split Form Differential Operator and Generalized Entropy Projection
Geng Liang, Junjie Wang and Hui Xu
This paper proposes a novel discretely
entropy conserving/stable flux reconstruction (FR) scheme for nonlinear conservation laws. The scheme combines a hybridized split-form differential operator with a generalized
entropy projection, enabling discrete
entropy conservation for arbitrary nodal distributions and arbitrary correction functions without modifying the original quadrature weights. The formulation is built directly upon the classical FR framework and is shown to preserve conservation properties while achieving
entropy conservation in the semi-discrete sense. Numerical experiments using the isentropic
vortex problem confirm the theoretically predicted accuracy and demonstrate robust
entropy behavior with
entropy-dissipative interface fluxes.
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Plasma Physics
Geodesic Acoustic Modes in pair plasmas confined in tokamak magnetic fields
Alessandro Biancalani
This paper is devoted to the derivation of the dispersion relation of the Geodesic Acoustic Mode in pair
plasmas, i.e. assuming that ions and electrons have the same mass. Geodesic Acoustic Modes are
plasma perturbations playing a crucial role in
turbulence regulation, and therefore in the determination of the
plasma confinement in tokamaks. Experiments with pair
plasmas, like electron-positron
plasmas, have been proposed with different kinds of confinements, and aim to study fundamental processes in
plasma physics and understanding the formation of the early universe.
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Fluid Dynamics
Multiscale Kinetic Methods for Nonequilibrium Flow and Transport
Zhaoli Guo and Kun Xu
Nonequilibrium flow and transport problems are inherently multiscale. Kinetic theory provides a fundamental physical basis for describing such phenomena, since it connects microscopic transport and interaction processes with emergent macroscopic behavior across regimes. In many situations, however, continuum descriptions lose validity in parts of the domain, whereas fully resolved kinetic descriptions become prohibitively expensive when numerical resolution remains tied to the smallest collision scales. Over the past two decades, a broad class of multiscale kinetic methods has therefore been developed to bridge rarefied, transitional, and continuum regimes in gas dynamics and other carrier-based transport systems. Existing reviews have clarified important parts of this field, including general numerical methods for kinetic equations, asymptotic-preserving methodology, and specific method families. This review adopts a different perspective by examining the subject through four interacting layers: numerical methods, computational strategies, asymptotic properties, and framework-level formulations. It surveys the main developments along these lines and emphasizes the common principles that connect them, including transport-interaction coupling, asymptotic consistency, scale-adaptive representation, and scale-dependent physical description. From this perspective, multiscale kinetic computation has evolved into a broader transport methodology for nonequilibrium systems across scales.
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Applied Physics · Cross-listed from cond-mat.mtrl-sci
Ferroelectric switching of odd-parity magnon spin splitting
Yuhan Liang, Xingyu Yan, Bowen Hao et al. (+13 more)
Magnetic symmetry can lift
spin degeneracy in momentum space without producing net magnetization, generating
spin textures classified by their parity under momentum reversal. Even-parity textures have well established in altermagnets. Odd-parity
spin textures have recently emerged in electronic bands of compensated magnets, but their counterpart in collective bosonic excitations remains experimentally unresolved.
Magnons provide a natural setting for this extension because they carry
spin angular momentum through insulating magnets without accompanying charge flow. Beyond realizing this missing state, a broader challenge is to program
spin splitting with voltage at room temperature. Here we report room-temperature transport evidence for ferroelectric switching odd-parity
magnon spin splitting in multiferroic BiFeO3.
Symmetry analysis and
spin-wave calculations reveal that the cycloidal chirality splits opposite-
spin magnon branches with an odd-in-momentum dependence and sets the sign. Experimentally, an injected in-plane-polarized
spin current generates an out-of-plane
magnon spin component during propagation. This component exhibits the crystalline angular dependence predicted by theory and reverses upon ferroelectric switching, providing a transport fingerprint of the
spin-split
magnon state. We use the programmed
magnon spin to drive deterministic field-free switching of a perpendicular ferromagnet and demonstrate XNOR logic-in-
memory. Our results extend odd-parity
spin splitting from fermionic electronic states to bosonic collective modes and establish nonvolatile electrical control at room temperature.
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All authors Yuhan Liang, Xingyu Yan, Bowen Hao, Ziye Zhu, Tianle Sui, Daniel Pharis, Xiaoxi Huang, Rakshit Jain, Tong Zhou, Di Yi, Wanjun Jiang, Pu Yu, Igor Žutić, Yuan-Hua Lin, Daniel C. Ralph, Tianxiang Nan
Optics
Dual-layer large-numerical-aperture metalenses with rotational zoom capability
Tingfeng Lei, Guanqing Shu and Xiaodong Chen
We present a non-paraxial design strategy based on the full ideal aberration-free phase function for a dual-layer rotational zoom metalens. By adopting the exact lens phase expression rather than the conventional parabolic approximation, this approach preserves the higher-order phase contributions critical to large-NA operation. Zooming is achieved by engineering complementary phase distributions on two metasurface layers and dynamically modulating their combined phase via controlled rotation. To realize the target phase profiles, a dielectric metasurface operating at 10 GHz is designed using ceramic cylindrical resonators arranged in a triangular
lattice. A systematic parametric optimization of
lattice period, cylinder diameter, and height ensures a complete 2pi phase coverage while maintaining a transmission above 85%. The resulting phase-geometry mapping establishes a reliable unit-
cell library for device implementation. Leveraging this library, the dual-layer metalens is designed and its performance evaluated through finite-difference time-domain simulations. A prototype with a 300 mm aperture is fabricated and experimentally characterized using three-dimensional near-field scanning measurements. Both simulations and experiments confirm that continuous focal-length tuning is achieved as the rotation angle varies from -60deg to 60deg, corresponding to a focal-length range of 100 to 300 mm and a zoom ratio of 3:1. The device achieves a maximum NA of 0.83, and the measured focal spots remain nearly diffraction-limited. The experimentally extracted focal-length variation agrees closely with theoretical predictions and simulations.
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Fluid Dynamics
Mechanism-Separated Closed-Form Transition Modeling via Field Inversion and Symbolic Regression
Seunghyun Joo, Younghyo Kim and Kwanjung Yee
Next-generation aircraft, rotorcraft, and wind turbines demand improved aerodynamic efficiency, making drag reduction a central design objective; in transition-sensitive configurations, the extent of laminar flow strongly affects viscous drag and performance. Accurate prediction of laminar-turbulent transition is therefore essential. Transport-equation-based transition models, however, increase computational cost and implementation complexity. Neural-network-based closures can be difficult to interpret and integrate into independent flow solvers, while a single compact correction trained on heterogeneous transition data may fail to preserve mechanism-specific behavior. This study develops a mechanism-separated transition model using field inversion and symbolic regression. The framework treats natural, crossflow, and separation-induced transition with separate correction branches and yields explicit, closed-form corrections to the Spalart-Allmaras production term, without additional transport equations or runtime neural-network inference. The closed-form model is implemented in an independent flow solver to assess implementation portability and is evaluated on canonical cases and complex three-dimensional configurations, including a natural-laminar-flow transport wing and a hovering rotor. Across the tested cases, the model captures the principal transition-front trends and associated aerodynamic-performance changes. For the hovering-rotor case, it requires about 55% of the wall-clock time of the comparable transport-equation transition model.
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Optics
Hypervectors from Optical Disorder: Programmable Encoding and Optical Inference for Hyperdimensional Computing
Takuya Iwata, Namthip Srisuthep and Satoshi Sunada
Hyperdimensional computing (HDC) is a computing framework that represents information as high-dimensional pseudorandom vectors called hypervectors (HVs), enabling learning and inference through simple algebraic operations. The HV dimensionality provides computational capacity and error robustness, but the required high-dimensional randomness must be stored or regenerated, imposing a
memory–computation tradeoff. Here, we address this tradeoff by physically embodying the randomness required for HV generation in the static disorder of a scattering medium. Specifically, a silicon photonic
circuit combined with the scattering medium generates high-dimensional HVs from a small number of input values in a single optical shot. Detector-side encoding programs HV correlations for continuous and categorical representations. The resulting HVs reproduce key statistical and compositional properties of ideal i.i.d.\ random HVs, including pairwise similarity statistics, associative-
memory capacity, and factorization capacity. We further demonstrate an optically assisted inference path using the generated HVs and optical similarity evaluation.
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Chemical Physics · Cross-listed from cond-mat.mtrl-sci
Polar vibrational excitations and glass-like response in relaxor PMN
Kehan Cai, Pinchen Xie, Yifan Li et al. (+1 more)
Relaxor ferroelectrics retain crystalline order while exhibiting glass-like dielectric and thermal responses. Using atomistic models trained on first-principles data, we investigate these responses in the prototypical relaxor Pb(Mg_{1/3}Nb_{2/3})O_3 (PMN). Compositional disorder couples elastic motion to electric polarization, producing a continuum of polar vibrational excitations, unlike the discrete polar optical modes of conventional ferroelectric PbTiO_3. The simulations qualitatively reproduce the temperature dependence of the low-frequency susceptibility, while the calculated far-infrared spectra agree closely with experiments. At low frequencies, disorder in PMN generates a
boson peak comprising excess
phonon-like modes and quasi-localized excitations. The latter exhibit a quartic frequency dependence of their density of states and pronounced anharmonicity, as in structural glasses. These excess modes account for PMN's anomalous behavior in the specific heat for temperature higher than 5 K. These results connect the dielectric, optical, and thermal anomalies of a crystalline relaxor through its disorder-induced polar excitation spectrum.
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All authors Kehan Cai, Pinchen Xie, Yifan Li, Roberto Car
Applied Physics · Cross-listed from eess.AS
Performance Analysis and Design of an Optomechanical Microphone Using an Integrated Photonic Waveguide Interferometer
Xiaoyu Niu, Yuqi Meng, Zihuan Liu et al. (+2 more)
We present an optomechanical microphone based on a diaphragm-integrated photonic waveguide Mach-Zehnder interferometer. Acoustic pressure deforms the MEMS diaphragm, inducing strain in the sensing waveguide and changing its optical path length. We analytically evaluate the optical and mechanical transduction mechanisms and key figures of merit, including signal-to-noise ratio, dynamic range, acoustic overload pressure, and minimum detectable pressure. Two design cases are considered: a MEMS microphone and a measurement microphone. The results indicate competitive performance but no substantial overall advantage over state-of-the-art microphones in conventional applications. The architecture may nevertheless offer advantages for high-temperature and other harsh-environment sensing applications.
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All authors Xiaoyu Niu, Yuqi Meng, Zihuan Liu, Ehsan Vatankhah, Neal Hall
Fluid Dynamics · Cross-listed from math.NA
Accurate wall shear stress in immersed flow analysis with application to point cloud-based CFD
Monu Jaiswal and Ming-Chen Hsu
Point cloud-based CFD enables flow analysis directly on discrete points obtained from 3D scanning and medical imaging, bypassing surface reconstruction, geometry cleanup, and boundary-fitted mesh generation. Derived from immersogeometric analysis, the method immerses the point cloud in a background mesh and enforces no-slip conditions on discrete points through a Nitsche-based weak boundary condition (BC). The framework delivers accurate velocity fields, pressure distribution, and integrated loads; however, accurate prediction of the local wall shear stress (WSS) has remained a critical challenge. The geometry intersects the background mesh arbitrarily, producing cut elements that lack the regularity required for consistent gradient evaluation. The issue is compounded by the stabilization term of the weak BC, whose parameter estimation in the symmetric Nitsche formulation is dependent on the cut configuration and affects the variationally consistent definition of traction from which the WSS is computed. In this work, we propose a new method to obtain accurate wall shear stress in immersed flow analysis with application to point cloud-based CFD, using a non-symmetric Nitsche's formulation with near-wall modeling and a patch-based stress recovery approach with traction compatibility. The method is validated on canonical
benchmarks and applied to turbulent flow past a sphere and to a patient-specific aorta, showcasing excellent agreement with reference results.
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Physics Education
Johann Bernoulli's analysis of elastic collisions (a teaching sequence to introduce the dynamic law thereby inspired)
Roberta T. Campos, Mariana F. B. Francisquini and Penha M. Cardozo Dias
In order to explain an elastic collision, Johann Bernoulli considered two bodies connected by a spring. Motion is defined as a succession of states of rest. Then, considering the spring to be a lever with a body at each extremity, the laws of
equilibrium imply that `motion' is described by the time variation of the (common) quantity of motion of the bodies; the dynamic law is thus deduced. This inspires a teaching sequence to introduce the dynamic law (in one dimension) in introductory physics course; we call it “bernoullian sequence”.
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Applied Physics · Cross-listed from cond-mat.stat-mech
Exact Nonperturbative Equilibrium Mode Statistics in Nonlinear Wave and Lattice Systems
Jialin Zhang, Yong Zhang and Hong Zhao
We derive exact finite-size nonperturbative representations of
equilibrium modal occupations and related statistics for three representative nonlinear systems: the Majda-McLaughlin-Tabak dispersive-wave model, the Fermi-Pasta-Ulam-Tsingou beta anharmonic chain, and the discrete nonlinear Schrodinger
lattice field. Independent simulations confirm the predictions from weak to strong nonlinearity. For DNLS, the theory remains accurate across the weak-coupling quasicondensation crossover, where large low-mode occupations and long-range coherence amplify interaction effects even when the bare nonlinear coefficient is small. The finite-ring DNLS occupations are further resolved into a positive sum of Rayleigh-Jeans channels with distinct correlation lengths, explaining when a single Rayleigh-Jeans law applies and why it fails near quasicondensation. In MMT and DNLS, the exact occupations also determine the mean modal frequencies even when the dynamical spectra broaden or split. The nonperturbative results allow a direct assessment of two representative perturbative approaches. Treating the mean interaction appropriately yields accurate low-order approximations, including at strong nonlinearity. At higher orders, however, the corrections cease to decrease and successive approximations oscillate with increasing amplitude; both finite-order approaches also fail near weak-coupling quasicondensation. Thus neither low-order agreement nor a small bare coupling guarantees a reliable perturbative description. The results establish nonperturbative
equilibrium theory for widely used nonlinear wave and
lattice models and provide a quantitative basis for modal distributions of energy, particles, and optical power in nonlinear optics, dispersive waves, anharmonic
lattices, and cold-atom systems.
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Optics
Yuchuan Chen, Jiacheng Zhao, Qiuran Zhu et al. (+1 more)
Femtosecond
laser pulses have incredible potential but still face some performance and stability issues. Here we discover a new nonlinear optical effect, frequency-comb-induced stimulated Brillouin scattering resonance, which can only be excited by a new type of
soliton, adaptive
solitons. Adaptive
solitons possess the unique properties of adaptive down-chirp which breaks area
theorem limitation on pulse energy in normal dispersion
lasers, spectral profile self-regulation which provides high pulse contrast and breaks gain narrowing limitation in amplifiers, and freedom from dispersive radiation that weakens and deforms current ultrashort
laser pulses in transmission media. More intriguingly, they have an adaptive transmission gain in normal dispersion waveguides which has the potential to enable them to be lossless in long normal dispersion waveguides for repeaterless
soliton communication. A passive frequency-modulation mode-locked fiber
laser was successfully built and generated incredibly stable adaptive
solitons. Even though the
laser had no negative dispersion elements, the output
solitons were measured as down-chirped which enables them to keep
soliton properties in normal dispersion waveguides, perfect for ultrafast applications with waveguide delivery. With the advantages of high consistency, high pulse contrast, and high energy capability; adaptive
solitons are excellent for fields including micromachining,
laser surgery,
quantum computing, and spectroscopy.
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All authors Yuchuan Chen, Jiacheng Zhao, Qiuran Zhu, Bill Chen
Optics
Synthetic-Aperture Super-Resolution Imaging via Spatial-Frequency Shift in Near-Field Diffraction
Qihao Sun, Chunzheng Bai, Wenjing Fang et al. (+5 more)
Grating-based computational imaging shifts high-spatial-frequency information into the detectable range, enabling super-resolution reconstruction. However, a fixed grating produces effective diffraction-mediated shifts only for specific spatial-frequency vectors, limiting spatial-frequency coverage. Here, we propose a synthetic-aperture super-resolution method in which repeated imaging with a rotating grating broadens spatial-frequency coverage and expands the effective aperture. A physics-prior-guided restoration framework then employs a multichannel deep-learning network to fuse images acquired at different grating orientations. Using diffraction images from only three grating orientations, the proposed method reconstructed the object with a resolution of $\lambda/3.9$. This approach offers a practical route to grating-modulated super-resolution imaging in systems with limited numerical aperture.
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All authors Qihao Sun, Chunzheng Bai, Wenjing Fang, Zongyan Zhang, Songlin Yang, Yonghong Ye, Mingyi Tao, Jiayu Zhang
Chemical Physics
From Heuristics to Machine Learning: The Performance Ceiling for Single-Ion Magnets and Its Electronic Origin
Federico Zahariev, Regina Pereyra, Vassiliki-Alexandra Glezakou et al. (+1 more)
Machine learning (ML) is expected to speed up the discovery of single-ion magnets (SIMs), but does the structural information available before synthesis allow such predictions? For 1215 lanthanide complexes from the SIMDAVIS 1.2.1 database we compared three increasing levels of structural description: tabular features of the coordination site, continuous
symmetry measures of the coordination polyhedron, and the complete 3D arrangement of atoms. All three converge to an accuracy near 76%, only slightly above the 71% of the single rule "predict SIM for Dy3+". To explain the failures, we combined multireference ab initio calculations with an inspection of the structures behind the high-confidence errors. The SIMs missed by the
geometric models are field-induced relaxers whose ground Kramers doublets are prone to tunnelling, a property invisible to
geometric descriptors. Many false positives contain several lanthanide centers or radicals, so their relaxation is collective and outside the single-ion picture. The electronic-structure and connectivity information needed to identify SIMs is therefore not accessible to
geometric methods alone.
Geometric models remain useful: restricting the screening to compounds with high prediction confidence raises the accuracy to 88% while retaining 48% of the
dataset. Building on the analysis of the failures, we propose a strategy that combines simple filters for nuclearity and for radicals with ligand-field descriptors from ab initio calculations.
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All authors Federico Zahariev, Regina Pereyra, Vassiliki-Alexandra Glezakou, Durga Paudyal
Optics
Sustained Orbital Motion Driven by Circularly Polarized Light in Nanoscale Stator-Rotor Architectures
Shiye Du, Juanshu Wu, Xin Chen et al. (+2 more)
Light-induced forces and torques offer a versatile strategy for remotely actuating microscopic objects, enabling breakthroughs including optical trapping and light-driven nanomachines. Extending such optical actuation to sustained cyclic motion, however, requires fundamentally distinct designs and, in particular, forces capable of delivering nonzero mechanical work over repeated cycles. Here, we demonstrate via simulations a nanoscale stator-rotor architecture, which achieves persistent orbital motion of a spherical rotor under circularly polarized plane-wave illumination. An off-center rotor displacement defines a stator-rotor structural polarity. Optical helicity coupled to this polarity generates a tangential force perpendicular to the instantaneous stator-rotor direction; as the rotor moves around the stator, the force direction rotates with it. Electrodynamic
symmetry analysis identifies this response as arising from antisymmetric, nonconservative forces that produce nonzero closed-cycle work, whereas linear polarization yields symmetric, conservative responses with zero closed-cycle work. Material screening and
Bayesian optimization identify an Ag-nanoshell design region, while Pareto analysis balances tangential actuation and radial confinement. A balanced candidate is predicted to lower the maximum steady-state temperature rise from 56.2 to 20.9 K relative to Au at the same light intensity. Brownian-dynamics simulations further show confined, helicity-defined orbital motion, with all 32 trajectories retaining the same circulation direction. These results establish a
symmetry-guided route toward sustained cyclic optical actuation at the nanoscale.
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All authors Shiye Du, Juanshu Wu, Xin Chen, Mouhong Lin, Hongyu Chen
Optics
Square-Root Higher-Order Exceptional Points with Symmetry-Induced Multiple Spectral Responses
Haoyang Zhang, Yadi Niu, Nuo Wang et al. (+2 more)
We generalize square-root procedure to non-Hermitian systems with finite
lattices, providing a spectral operation scheme applicable to arbitrary tight-binding models. Via this generalized square-root approach, we construct novel chiral-symmetric higher-order exceptional points (EPs) with multiple spectral responses. By taking square-root of a parent
Hamiltonian hosting an $n$th-order EP (EP$_n$), an EP$_{2n+1}$ chiral-symmetric square-root system is obtained, whose
lattice sites are inherited from both the parent system and an auxiliary residual system. The chiral-
symmetry-induced structure of the generalized eigenspace enables onsite and coupling perturbations to selectively generate spectral responses of different orders. The proposed scheme is universal, applicable to any existing tight-binding EP system and iterable to generate EPs of arbitrarily high order. With enriched ultrasensitive spectral responses, the chiral-symmetric higher-order EP system provides a promising platform for signal amplification, detection and non-Hermitian control.
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All authors Haoyang Zhang, Yadi Niu, Nuo Wang, Zihan Mo, Ying Gu
Instrumentation and Detectors · Cross-listed from cond-mat.mes-hall
Scalable Multiple Electron Transport Architectures for Feedback Traceable Current Sources
Agustin Javier Lapi, Guillermo Fernandez Moroni, Fernando Chierchie et al. (+8 more)
We present a scalable electron-counting current
cell based on a floating gate architecture operated as a Multiple Electron Transport device (MET). The system enables controlled injection, transport, and precise quantification of discrete charge packets using the sensor non-destructive multiple readout capability. We repurposed the charge-injection technique, jointly with the electron-resolution capability, for a controlled generation of quantized charge packets for an electron-traceable current source. Scalable architectures based on parallel and series multi-amplifier configurations are explored. Experimental results confirm noise reduction following the square root of the number of independent measurements and demonstrate stable, programmable output current. This approach provides a compact and scalable platform for electron-counting current sources and precision
quantum metrology applications.
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All authors Agustin Javier Lapi, Guillermo Fernandez Moroni, Fernando Chierchie, Fabricio Alcalde Bessia, Miqueas Ezequiel Gamero, Brenda Aurea Cervantes Vergara, Blas Junior Irigoyen Gimenez, Eduardo Paolini, Claudio Rodrigo Chavez Blanco, Juan Estrada, Javier Tiffenberg
Atmospheric and Oceanic Physics
Conservation Constraints and Distributed Advective Memory in a Reduced Model of Atlantic Overturning Hysteresis
Sandy Hardian Susanto Herho, Iwan Pramesti Anwar, Mutiara Rachmat Putri et al. (+3 more)
Interbasin exchange through the Indo-Pacific gateway supplies salt to the Atlantic and is widely invoked as a control on the stability of the Atlantic overturning circulation. We ask whether that control can act on the
equilibrium structure of a conceptual thermohaline model. A closed five-box model with an exact salt invariant is constructed, comprising North Atlantic, upper-limb, Indian, Pacific, and deep reservoirs, with the return flow split between a warm route through the Indian reservoir and a cold route, together with an Indonesian Throughflow branch and an Agulhas retroflection. Adding the steady-state budgets of the gateway reservoirs shows that every internal exchange cancels, so the salt they export to the Atlantic is fixed by the net Atlantic freshwater export alone. This holds independently of the warm-route fraction, the throughflow, the retroflection, and how the export is apportioned among gateway reservoirs; across a parameter sweep the largest departure is of order ten to the minus eleven. The gateway therefore enters as a purely additive forcing and cannot renormalize the salt-advection feedback. Replacing the discrete transit lag by a gamma
memory kernel leaves the
equilibria unchanged but yields a closed-form threshold for oscillatory instability depending only on kernel shape. Broad
memory is strongly stabilizing, and a discrete lag is the least stable member of the family. Because the instantaneous feedback vanishes at the fold, oscillatory instability always precedes the saddle-node, over an interval widening more than tenfold as
memory sharpens. Gateways therefore appear to act on transient rather than
equilibrium dynamics
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All authors Sandy Hardian Susanto Herho, Iwan Pramesti Anwar, Mutiara Rachmat Putri, Rusmawan Suwarman, Deny Juanda Puradimaja, Dasapta Erwin Irawan
Biological Physics · Cross-listed from cs.LG
MGRD: Compact morphology-gated residual diffusion for variance-aware cross-domain neurite forecasting
Tsung Yeh Hsieh, Cosmin Anitescu, Chunghwan Kim et al. (+2 more)
Tracking neurite morphology over time helps characterize structural changes during neuronal development and deterioration, but long-term time-lapse imaging is resource-intensive and difficult to scale. Forecasting future morphology could reduce this burden. Existing neurite digital-twin models such as gated spatiotemporal
attention (gSTA) produce a single deterministic forecast without representing variability among plausible futures. We introduce Morphology-Gated Residual
Diffusion (MGRD), a compact
stochastic surrogate that jointly forecasts twenty future neurite-morphology frames from ten observed frames while conditioning on morphology features derived from the latest observation. On controlled phase-field trajectories, MGRD reduces trajectory-wise mean MAE by 9.7% relative to a matched control while updating 4.46 times fewer parameters. On human iPSC-derived
neuron microscopy, MGRD improves all four reported metrics over gSTA, including a 39.6% reduction in trajectory-wise mean MAE and a 45.3% increase in skeleton F1. Without mouse-domain retraining or fine-tuning, MGRD also improves MAE and skeleton F1 on mouse cortical-neurosphere microscopy across 10-40-min sampling intervals and forecast horizons beyond 13 hours. Repeated sampling provides a case-level variance score for ranking forecast difficulty. Retaining approximately 60% of the lowest-variance cases reduces mean MAE by 17.6% on iPSC microscopy and 16.8% on simulation data. MGRD uses 1.01% of gSTA's parameters, requires less than one tenth of its training-update time, and generates a 50-step DDIM trajectory 7.9% faster when morphology features are cached. These results establish MGRD as a compact
stochastic surrogate for neurite-morphology forecasting and case prioritization across simulation and microscopy
datasets.
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All authors Tsung Yeh Hsieh, Cosmin Anitescu, Chunghwan Kim, Victoria A. Webster-Wood, Yongjie Jessica Zhang
Computational Physics · Cross-listed from cond-mat.mtrl-sci
Transitions between bulk and interfacial fracture in diamond/$c$BN heterostructures
Wei Qiu, Feiyu Zhou, Xiaonan Wang et al. (+5 more)
Whether an initially crack-free
heterostructure fails at its interface or within an adjoining phase is controlled by the relative cohesion of competing atomic planes, but how interfacial chemistry, crystallographic orientation, and intermixing reshape this competition remains unclear. Here, we combine density functional theory (DFT) with a fine-tuned atomistic foundation model to resolve tensile fracture in coherent diamond/cubic boron nitride (cBN)
heterostructures. The resulting potential reproduces independent DFT tensile responses, including an unseen (001) interface orientation. Interfacial termination, orientation, and
diffusion-induced intermixing jointly determine fracture resistance and fracture-plane selection. C-N-bonded (111) and C-B-bonded (001) remain interface-controlled throughout the investigated intermixing range, whereas pristine C-B-bonded (111) fractures at a neighboring B-N plane inside cBN because the interface is more strongly bound. Increasing the
diffusion fraction from 0 to 50.0% causes a nonlinear decrease in fracture strength from 50.3 to 15.8 GPa and drives a bulk-to-interface transition through three regimes: cBN fracture up to 4.86%, configuration-dependent competition between 7.6 and 10.1%, and interfacial fracture at 12.5% and above. Atom-resolved stress fields and DFT separation energetics show that this transition is associated with stress relocation and a reversal in the relative cohesion of competing planes, while electron localization analysis connects the cohesion hierarchy to termination- and orientation-dependent bonding. These results establish an atomistic framework for controlling fracture resistance and fracture pathways in strongly bonded
heterostructures.
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All authors Wei Qiu, Feiyu Zhou, Xiaonan Wang, Feng Xie, Yan Chen, Shengying Yue, Yilun Liu, Penghua Ying