Space Physics
Cometary ion dynamics at a weakly outgassing comet
Victor Steinwand, Peter Stephenson, Zoe Lewis et al. (+3 more)
The ESA/Rosetta mission escorted comet 67P/Churyumov-Gerasimenko for two years, exploring its
plasma environment across diverse outgassing conditions.
Plasma density observations from the Rosetta
Plasma Consortium (RPC) are broadly categorized into two regimes for the ion dynamics, linked to the presence of a diamagnetic cavity at Rosetta's location. With a diamagnetic cavity present, ions detected by Rosetta are accelerated with respect to the neutral coma. Without a diamagnetic cavity present, at lower outgassing, and nearer the
nucleus, ions co-move with the neutrals. We examine the transition between regimes following Rosetta's last detection of the cavity in February 2016. During this transition, global 3D
plasma models of the cometary ionosphere underestimate
plasma densities. To investigate this underestimation, we assess the sensitivity of cometary ion densities to different parameters using a 3D collisional ion test particle model, driven by electromagnetic fields from hybrid modeling. We show that considering cometary electron cooling is necessary to model cometary ion dynamics within 100 km of the surface. Electron temperatures derived from collisional electron modeling affect ion dynamics via the ambipolar electric field, increasing ion number densities. We further show that the cometary electron cooling exobase organizes Rosetta
plasma density observations; different ion dynamics regimes are linked to the position of Rosetta relative to the exobase. These findings demonstrate that Rosetta was below this exobase for much of the post-perihelion period. They justify the absence of ion acceleration in
plasma density assessments and the use of uniform electron-impact ionization frequencies between Rosetta and the surface during post-perihelion.
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All authors Victor Steinwand, Peter Stephenson, Zoe Lewis, Esa Kallio, Arnaud Beth, Marina Galand
Computational Physics · Cross-listed from cond-mat.soft
Mesoscopic simulations of linear and ring polymer solutions with explicit hydrodynamics under good and poor solvent conditions
Ashish Kumar Singh and Angelo Rosa
We employ large-scale Dissipative Particle Dynamics simulations to investigate dilute solutions of linear
polymers and unknotted, non-concatenated ring
polymers in explicit solvent. By systematically varying solvent quality, we examine the interplay between hydrodynamic interactions, chain architecture, and intermolecular association. Under good solvent conditions, both linear and ring
polymers remain expanded and well dispersed, displaying center-of-mass dynamics consistent with normal
diffusion. In poor solvents, attractive
polymer-
polymer interactions drive the formation of irregular aggregates characterized by partial chain collapse, substantial interpenetration, and slower dynamics. Despite their different
topologies, the two
polymer architectures exhibit remarkably similar structural and dynamical responses across the solvent conditions considered. These results indicate that solvent quality largely determines the organization and transport properties of dilute
polymer solutions, whereas topological effects remain comparatively weak in the investigated regime.
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Chemical Physics
An Additive Reference Correction Scheme for the Transcorrelated Method
Johannes Hauskrecht, Kristoffer Simula, Yifan Cheng et al. (+3 more)
We introduce an additive reference correction for the transcorrelated (TC) method and its three-body mean-field approximation (xTC), to improve energy differences computed in small orbital basis sets. The correction is motivated by the observation that, for xTC atomization energies, the dominant error in double-{\zeta} bases originates from the reference contribution rather than from the correlation energy. In the proposed reference-corrected scheme (RC-xTC), the small-basis correlation energy is retained, while the corresponding TC reference energy is replaced by its value from a larger basis.
Benchmark calculations for the non-relativistic HEAT set with the Dunning basis-set family show that RC-xTC substantially improves both total and atomization energies relative to standard xTC in double-{\zeta} bases. At the CCSD(T) level, RC-xTC yields better atomization energies than CCSD(T)-F12a in the double-{\zeta} regime, while preserving the favorable total-energy accuracy of xTC. At the CCSD level, RC-xTC improves atomization energies relative to F12a throughout the full basis-set sequence. As the basis set is enlarged, xTC and RC-xTC become progressively identical, as expected from the construction of the correction.
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All authors Johannes Hauskrecht, Kristoffer Simula, Yifan Cheng, Evelin Martine Corvid Christlmaier, Daniel Kats, Ali Alavi
Accelerator Physics
Time domain analysis of bunched e-beam tapering-enhanced superradiance at zero-slippage conditions
Amir Weinberg, Leon Feigin, Ariel Nause et al. (+1 more)
Exceptionally, a bunched electron beam can get trapped by its own spontaneously emitted synchrotron undulator radiation in the self-interaction scheme of TES (Tapering Enhanced Superradiance). In this scheme, excess radiative energy is extracted from the beam by tapering the undulator after the bunch trapping. To avoid slippage of the radiation wavepacket away from the bunch, the interaction takes place in a waveguide with a slow group velocity mode. Here we study the time domain waveform of the Electric Field and the radiation energy buildup in this scheme. We compare its analytical theory and numerical simulations in an ideal exemplary setup based on a rectangular waveguide and a planar undulator
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All authors Amir Weinberg, Leon Feigin, Ariel Nause, Avraham Gover
History and Philosophy of Physics
The Dynamics of Quantum Gravity: the Missing Piece in the Spacetime Emergentist Account
Álvaro Mozota Frauca
Quantum gravity suggests that spacetime may not be fundamental, and it has been argued that we can understand a theory without a fundamental spacetime if we are able to claim that spacetime `emerges' from some non-spatiotemporal entities. In this sense, strategies like functionalism have been deployed to claim that this emergence is possible and plausible, both in principle and in practice for current approaches to
quantum gravity. In this article I argue that this analysis is incomplete, as it tends to overlook the way the dynamics of these theories is `
quantum' in a way that differs from standard
quantum theory. The challenge for the emergentist (and for the
quantum gravity theorist) is to give an interpretation not only to the kinematical and classical aspects of these theories, but to the dynamical and
quantum ones, and to show how the spacetime roles can be fulfilled, if possible at all. Therefore, I argue that some current approaches to
quantum gravity seem to fail to provide meaningful theories, that spacetime functionalism is of no help, and that the position of the spacetime emergentists is weakened, as they lack any example of a successful reduction of spacetime to some truly
quantum non-spatiotemporal stuff.
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Chemical Physics
A harmonically-coupled-anharmonic-oscillator approach for polyatomic chemistry modeling in DSMC
Simone Lauterbach, Franziska Tuttas and Marcel Pfeiffer
Atmospheric entry processes are characterized by high-enthalpy gas flows in strong thermo-chemical non-
equilibrium. Accurate simulations of such conditions remain challenging due to the extreme conditions and the complex influence of internal energy modes. In particular, the common assumption of uncoupled harmonic vibrations may break down, and excited internal energy states can directly influence reaction rates. Previously, an anharmonic oscillator model has been developed by Civrais et al. to improve the accuracy of the Direct Simulation Monte Carlo (DSMC) method under such conditions. However, this extension has so far been limited to diatomic molecules. To increase the accuracy of the DSMC method in the open-source code PICLas, the anharmonic oscillator model is extended to include polyatomic species. The proposed model explicitly considers anharmonic effects and intramolecular energy redistribution. Vibrational degrees of freedom are treated in a local mode basis, in which anharmonic stretching modes are harmonically coupled by harmonic bending modes. The coupling allows for the redistribution of localized vibrational excitation. Dissociation can occur by the strong excitation of a stretching mode, and specific modes can be coupled to the reaction coordinate of the transition state in bimolecular exchange reactions. The newly developed model is evaluated by the comparison to high-fidelity calculations for a set of representative processes. Investigated are different dissociation reactions, which exhibit a high degree of energy redistribution, and the hydrogen-exchange reaction between methane and a hydrogen radical, in which only selected modes contribute to the reactive process. In addition, the recombination-dissociation
equilibrium system has been investigated for methane.
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Optics · Cross-listed from quant-ph
Nonlinear Schrödinger equations: Symmetries, superposition, and classicality from a Bohmian perspective
Ángel S. Sanz
Interference is commonly regarded as the most direct manifestation of the superposition principle. This association is natural for the linear Schrödinger equation, where coherent alternatives combine at the level of probability amplitudes. However, the situation becomes less transparent when nonlinear couplings are present, or when the field is only partially coherent. In this work, we argue that a more robust organizing principle is provided by the local flow generated by phase variations. In this sense, phase-induced flow acts as a unifying mechanism for interference-like dynamics in nonlinear and partially coherent Schrödinger systems. The discussion is developed from a hydrodynamic, or Bohmian, perspective, understood here as a practical probing tool rather than as an additional ontology. Three representative situations are considered: interfering Bose–Einstein condensates described by the Gross–Pitaevskii equation, nonlinear Schrödinger dynamics obtained by modifying the
quantum-potential contribution, and partially coherent Airy beams described through their cross-spectral density. Although these systems differ in physical origin and mathematical implementation, they share a common dynamical structure: density-related observables are shaped by velocity fields determined by phase, or ensemble-phase, information. From this viewpoint, interference-like traits, localization, self-acceleration and coherence loss can be interpreted in terms of the preservation, deformation or breaking of the
symmetries displayed by the underlying flow. This provides a compact way of connecting interference, nonlinear dynamics, classicality, coherence loss, and structured-light propagation within a single trajectory-based framework.
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Chemical Physics
A unified formalism for collinear and non-collinear approaches in the four-component Dirac-Kohn-Sham theory based on G-spinors
Giulia Gamboni, Loriano Storchi, Paola Belanzoni et al. (+1 more)
Non-collinear density functional theories were developed to extend the use of established collinear exchange-correlation functionals to systems with unpaired electrons in the presence of significant
spin-orbit coupling. A comparison of different approaches and implementations is not straightforward, as the methods are often formulated using different fundamental variables and numerical approximations. A consistent review of the formal and numerical aspects of collinear and non-collinear schemes has recently been reported (Desmarais et al., J. Chem. Phys. 154, 204110 (2021)) in the context of two-component methods. In this work, we present an initial effort towards a unified formulation of collinear and non-collinear approximations, encompassing both canonical and Scalmani-Frisch schemes, within the relativistic four-component DKS formalism based on G-spinor basis sets. Our preliminary implementation of the collinear and canonical non-collinear formulations in the DKS module of the BERTHA code extends its applicability and provides a
benchmark for a series of simple open-shell hydride molecules (namely, H$_2$X$^+$, with X = O, S, Se, Te, and Po). Finally, we show that incorporating the magnetisation vector into the reformulated non-collinear canonical LDA approach enables a description of H$_2$ dissociation - and open-shell systems more broadly - that closely parallels unrestricted non-relativistic approaches, notably without explicitly imposing the broken
symmetry solution as is often required in non-relativistic collinear calculations. This unified formulation forms the basis for a rigorous comparison between different numerical approximations, which will be essential for obtaining stable results for the non-collinear GGA exchange-correlation functionals.
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All authors Giulia Gamboni, Loriano Storchi, Paola Belanzoni, Leonardo Belpassi
Optics
Pulse-to-pulse spectral phase characterization of mid-infrared pulses at megahertz rates
Zhihao Deng, Zicong Xu, Kazuki Hashimoto et al. (+3 more)
Pulse-resolved spectral phase measurement of mid-infrared (MIR) pulses is essential for many applications, from precise waveform control to ultrafast
quantum optics. However, conventional MIR pulse characterization techniques are typically limited to sub-kHz-rate operation, leaving a substantial speed mismatch with MIR sources operating at kHz or MHz rates. Here, we introduce time-stretch upconversion-based mid-infrared pulse evaluation (TSUBAME), a technique that enables pulse-to-pulse spectral phase characterization of ultrashort MIR pulses at the
laser repetition rate. TSUBAME combines MIR-to-NIR (near-infrared) upconversion, time-stretch, and spectral interferometry to achieve scan-free high-speed spectral phase measurements. We validated the technique by measuring MIR pulses spanning 4.98-5.30 um while introducing well-defined dispersion, obtaining excellent agreement with theoretical predictions. Operating at a measurement rate of 1 MHz, TSUBAME achieves the fastest single-pulse-resolved spectral phase characterization of MIR pulses reported to date. As a further demonstration, we captured dynamic spectral phase variations on a microsecond timescale. TSUBAME provides a powerful tool for real-time monitoring and optimization of high-repetition-rate MIR pulses, with potential applications in strong-field physics, high-harmonic generation, and coherent molecular control.
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All authors Zhihao Deng, Zicong Xu, Kazuki Hashimoto, Gabriel Demontigny, Denis V. Seletskiy, Takuro Ideguchi
Space Physics · Cross-listed from astro-ph.SR
Role of SKA in Advancing Remote Measurements of Magnetic Fields of Solar Coronal Mass Ejections
Devojyoti Kansabanik, Surajit Mondal, Shaheda Begum Shaik et al. (+13 more)
Coronal Mass Ejections (CMEs) are large expulsions of magnetized
plasma from the Sun into interplanetary space and are the primary drivers of extreme space weather variations. The strength and
topology of CME
magnetic fields largely determine their impact on Earth. Although visible-light coronagraphs routinely observe CMEs and provide their
geometric and kinematic properties, they cannot directly measure CME vector
magnetic fields. These fields evolve from initiation through the inner heliosphere due to interactions with other CMEs, coronal structures, and the ambient
solar wind, leading to significant structural deformation. Such
evolution complicates predictions of the CME
magnetic field at Earth. Accurate measurements of CME
magnetic fields in the corona and heliosphere are therefore essential for advancing space weather
forecasting.
Radio observations spanning MHz to GHz frequencies provide a powerful remote-sensing approach for measuring CME
magnetic fields from the ground. Recent observations with Square Kilometre Array (SKA) precursors and pathfinder instruments, as well as other new-generation facilities, have demonstrated the potential of these
radio techniques for CME
magnetic-field diagnostics. At the same time, these studies have highlighted several limitations of current instruments. The higher sensitivity, wider instantaneous bandwidth, and broader frequency coverage of the SKA will open a new observational window, enabling these techniques to be fully exploited for constraining SpWx models and improving predictive accuracy. However, such observations are non-standard and require special consideration in scheduling, calibration, and imaging. Developments achieved with SKA precursors and pathfinders are paving the way for robust CME
magnetic-field measurements with the SKA.
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All authors Devojyoti Kansabanik, Surajit Mondal, Shaheda Begum Shaik, Peijin Zhang, Puja Majee, Angelos Vourlidas, John Morgan, Divya Oberoi, Anshu Kumari, Alec Thomson, Bin Chen, Carl Shneider, Hariharan Krishnan, Kamen Kozarev, Sneha Pandit, Vanessa Moss
Optics
Plasmonic-cavity Modulator for the Mid-IR with a Semi-transparent and Nonlinear Heavily-doped Semiconductor Mirror
Tommaso Venanzi, Raffaella Polito, Andrea Rossetti et al. (+15 more)
We present a free-space plasmonic modulator based on a single heavily-doped
semiconductor layer. We investigate its ability to modulate both the linear and nonlinear response at mid-infrared frequencies slightly below the
plasma frequency of the
semiconductor. We demonstrate electric control of the linear transmittance and reflectance, and of the efficiency of third-harmonic generation with a field-effect gate structure. We discuss further performance optimization of the device in terms of modulation speed and depth towards a fast modulator with very simple active material requirements. Our results establish a viable route toward practical plasmonic modulators and mixers operating in the mid-infrared atmospheric window available for free-space communications at wavelengths between 8 and 12 um.
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All authors Tommaso Venanzi, Raffaella Polito, Andrea Rossetti, Markus Ludwig, Daniele Brida, Adel Bousseksou, Isabelle Sagnes, Gregoire Beaudoin, Raffaele Colombelli, Antonio Valletta, Andrea Notargiacomo, Francesco Mattioli, Gonzalo Alvarez-Pérez, Cristian Ciracì, Valeria Giliberti, Marialilia Pea, Michele Ortolani, Huatian Hu
Space Physics
David Pelosi, Fernando Barão, Bruna Bertucci et al. (+3 more)
The modulation of
galactic cosmic rays, driven by the
evolution of the heliospheric
magnetic field, strongly influences the intensity of
cosmic rays reaching near-Earth space. Characterizing this process is crucial both for advancing our understanding of
cosmic-ray transport and for assessing radiation exposure and related hazards in space environments. Here we present a newly developed
forecasting framework built on a numerical description of charged particle transport in the heliosphere and its dependence on
solar activity, designed for the long-term
forecasting of
galactic cosmic-ray fluxes. It solves a one-dimensional, spherically symmetric form of the Parker transport equation, including
diffusion,
solar-wind advection, and adiabatic energy losses. The model has been validated using multi-species flux measurements from space-based experiments: PAMELA, AMS-02, and ACE. Its strategy is based on
Hilbert-Huang transform filtering and cross-correlation between delayed
solar proxies and effective model parameters. Our charge-sign- and
rigidity-dependent parametric description of the
diffusion-advection processes yields good overall agreement with the data, as shown by the reconstruction uncertainty. The robustness of this approach is validated across a broad set of multichannel
datasets covering different particle species, energy ranges, and phases of
solar activity, supporting its applicability to space radiation monitoring and
forecasting. Furthermore, when coupled with
solar-proxy
forecasting models, it enables decadal-scale predictions of
galactic cosmic-ray fluxes, thereby supporting long-term planning and radiation-risk assessment for future space missions.
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All authors David Pelosi, Fernando Barão, Bruna Bertucci, Emanuele Fiandrini, Miguel Orcinha, Nicola Tomassetti
Applied Physics
Fully compensated ferrimagnetic triferroics and multistate transport in hidden-phase wurtzite MnSe monolayer
Zhuang Ma, Hongfei Liang, Po Ma et al. (+5 more)
Fully compensated ferrimagnets (fFIMs) have attracted interest due to their compensated moments and nonrelativistic
spin splitting across the Brillouin zone. Known fFIMs, however, are mostly restricted to complex three-dimensional (3D) systems or require external fields in two-dimensional (2D)
heterostructures, leaving intrinsic fFIM monolayers unexplored. We identify a hidden-phase MnSe monolayer, derived from the (001) planes of wurtzite, as an intrinsic fFIM featuring inequivalent sublattices not linked by any
symmetry. It is a unipolar
magnetic semiconductor (UMS) with perpendicular
magnetic anisotropy (528.60 * 10^-3 eV per unit
cell) and simultaneously exhibits ferroelectricity (polarization 4.63 * 10^-10 C/m) and ferroelasticity (signal 61%), with barriers of 7.6 * 10^-3 and 0.10 eV/f.u., respectively, establishing a single-phase triferroic system. The ground fFIM UMS characteristics are robust against strain up to 3%. The In2Se3/MnSe
heterostructure enables nonvolatile electrical control between semiconducting and metallic states. Constructed tunnel junctions exhibit
giant tunneling magnetoresistance (2.98 * 10^5%), electroresistance (6.97 * 10^14%), elastoresistance (7.95 * 10^4%), and near-perfect
spin filtering (~100%). Collectively, this spontaneous 2D fFIM with coexisting triferroic orders provides a promising platform for ultrahigh-density, low-power, and miniaturized
memory devices.
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All authors Zhuang Ma, Hongfei Liang, Po Ma, Guangqian Ding, Xuehao Wu, Sikander Azam, Guoying Gao, Long Zhang
Computational Physics · Cross-listed from cond-mat.mtrl-sci
Side-Chain Tuning of Thermal-Expansion Crossover in Metal-Organic Frameworks
Wei Qiu and Penghua Ying
Achieving continuous control over macroscopic thermal expansion remains a fundamental challenge in solid-state physics. Using classical and path-integral molecular dynamics alongside
lattice dynamics at near-ab initio accuracy, we report an
entropy-driven thermal-expansion crossover from positive (PTE) to negative thermal expansion (NTE) in alkoxy-functionalized MOF-5, an archetypal metal-organic framework (MOF). We demonstrate that this non-linear response is continuously tunable via the alkoxy side-chain length, quantified by the number of carbon atoms $n$ grafted onto the archetypal cubic MOF-5 framework: systems with short chains ($n \le 2$) exhibit monotonic NTE, whereas longer chains ($n \ge 3$) trigger a pronounced PTE-to-NTE crossover. At low temperatures, thermal activation of longer side chains opens additional conformational states and generates steric pressure inside the pore, driving positive expansion through a gain in side-chain conformational
entropy. Conversely, at elevated temperatures, the side chains enhance transverse linker fluctuations and strengthen the string-tension mechanism associated with low-frequency framework modes, causing structural contraction favored by framework vibrational
entropy. Finally, by varying the concentration of side-chain-functionalized linkers, the thermal expansion coefficient can be continuously regulated to realize negative, near-zero, and positive thermal expansion within selected temperature windows. These results establish side-chain engineering as a practical route for programming macroscopic thermodynamic responses in MOFs.
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Physics and Society
When one protocol fits none: Self-organized network routing through evolutionary game dynamics
Francesca Dilisante, Pablo Gallarta-Sáenz, Luciano Stucchi et al. (+2 more)
Packet routing on scale-free networks faces a fundamental trade-off: shortest-path routing is efficient at low demand but funnels traffic through hubs and jams early, whereas congestion-aware routing postpones jamming at the price of a sharper collapse. Since neither paradigm dominates across the full range of traffic load, here we ask whether the appropriate balance can emerge endogenously rather than being imposed by design. To answer this, we recast adaptive packet routing on networks as an evolutionary game letting a heterogeneous population of strategies compete for prevalence under selection pressure generated by their own performance. We study this competition under two formalisms (strategy anchored to the packet or to the generating node), global and local update rules, and two payoff metrics. Across every implementation the evolutionary dynamics yield the same outcome: the jamming transition is delayed relative to shortest-path routing while the violent collapse of fixed congestion-aware routing is avoided. This improvement emerges spontaneously, without centralized coordination or global information. Crucially, under local update rules, the node-level
volatility of strategy choices peaks sharply at the transition, furnishing a purely local early-warning signal of imminent jamming that requires no global monitoring.
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All authors Francesca Dilisante, Pablo Gallarta-Sáenz, Luciano Stucchi, Sandro Meloni, Jesús Gómez-Gardeñes
Optics
Reconfigurable wavelength-encoded stochastic illumination for active hyperspectral imaging
Yi-Jing Chen, Bao-Lei Liu, Ze-Yuan Dong et al. (+6 more)
Traditional hyperspectral imaging (HSI) relies on sequential scanning with complex and bulky hardware, inherently limiting its temporal resolution while increasing system complexity and cost. Computational HSI offers cost-effective alternatives with simplified hardware. However, most existing computational methods rely on fixed spectral encoding units, which lack adaptability for different spectral tasks. Here, we present a reconfigurable optical
stochastic encoding (ROSE) framework with programmable illumination, which can be adaptively optimized for different spectral tasks, for high-throughput, compressive HSI. By leveraging an array of monochromatic light-emitting diodes (LEDs), we synthesize
stochastic spectral patterns that enable compressive acquisition using a standard monochrome camera. The proposed framework allows dynamic reconfiguration of illumination patterns, making it adaptable to diverse imaging requirements. We experimentally validate the proposed method and achieve HSI with a spatial resolution of 2048 by 1536, reconstructing 60 spectral bands across the spectral range of 400-700 nm. Furthermore, we introduce an automatic optimization strategy to search for optimal illuminations tailored to specific tasks, improving both reconstruction accuracy and task-oriented performance. We demonstrate the effectiveness of our approach in applications including anti-counterfeiting inspection and oral imaging, and further validate its compatibility with standard microscope and endoscope systems. The developed ROSE illumination module could serve as a universal, plug-and-play add-on for conventional cameras and existing optical systems, providing a cost-effective pathway to upgrade them into high-performance, task-adaptive HSI systems.
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All authors Yi-Jing Chen, Bao-Lei Liu, Ze-Yuan Dong, Zhi-Hao Zhao, Yi-Ying Zhang, Chun-Min Yu, Zhi-Hua Xu, Yuan-Jin Yu, Zhao-Hua Yang
Computational Physics
P3MaZe: a Mass-Zero constrained-dynamics formulation of particle-mesh electrostatics
Federica Troni, Violette Gontran, Davide Grassano et al. (+1 more)
We introduce P3MaZe, a real-space particle-mesh electrostatic method that combines the standard short-range/long-range decomposition of Particle-Particle Particle-Mesh (P3M) electrostatics with the Mass-Zero constrained dynamics (MaZe) framework. In this formulation, the smooth long-range electrostatic potential is represented on a mesh as a zero-inertia auxiliary field, while the discretized Poisson equation is enforced as a holonomic constraint during molecular dynamics. By retaining the standard P3M decomposition, P3MaZe preserves the systematic accuracy controls associated with the real-space cutoff, the Ewald splitting, the mesh spacing, and the charge assignment procedure, while replacing the conventional multigrid Poisson solver by a constrained correction problem. The method is validated for molten NaCl and simple point-charge flexible water (SPC/Fw). Values of the potential, structural, translational, collective, and rotational dynamical observables are in quantitative agreement with those obtained with established electrostatic methods, including real-space P3M, and Ewald summation. We further show that, for the linear, time-independent Poisson operator considered here, the constrained correction problem is algebraically equivalent to a direct Poisson solve initialized by a chronological extrapolation of the mesh potential - a connection not previously established for MaZe-based approaches. This result identifies the precise mechanism through which acceleration of the iterative long-range solve is achieved, and we exploit it systematically through higher-order predictors to further improve convergence, while retaining the expected linear scaling with system size. Because the underlying extrapolation is independent of the constrained-dynamics formalism, it can, of course, also be used directly to accelerate conventional iterative real-space Poisson solvers.
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All authors Federica Troni, Violette Gontran, Davide Grassano, Sara Bonella
Chemical Physics · Cross-listed from cond-mat.mtrl-sci
From Materials Database to Materials Bank: Assetizing Data for AI Driven Materials Innovation
Chenyao Ma, Di Zhang, Weibo Gong et al. (+9 more)
Driven by high-throughput experimentation, computational modeling, and artificial intelligence (AI), materials data has expanded at an unprecedented rate. Conventional materials databases function only as passive repositories, archiving raw experimental records indiscriminately including both successful and failed data, without systematic value filtering or asset management. This creates a critical gap between massive data accumulation and actionable innovation, hindering the identification of high-potential materials and industrial translation. To address this bottleneck, we propose an industrialization-oriented Materials Bank, a dedicated valuefiltering and assetization layer that operates beyond traditional databases. It does not merely curate high-quality data but systematically elevates qualified candidates into standardized, upgradable materials assets via a multi-dimensional BankCard framework covering scientific validity, synthesis feasibility, application readiness, and industrial value. By unifying databases, AI models, automated experimentation, and multi-criteria assessment into a cohesive closed-loop ecosystem, the Materials Bank establishes a clear trajectory from data to knowledge, candidate, asset, and product. It serves not as an enhanced database or screening tool, but as a decision infrastructure bridging academic discovery and industrial demand, offering a scalable paradigm to accelerate AI-driven materials innovation and deliver tangible real-world impact.
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All authors Chenyao Ma, Di Zhang, Weibo Gong, Wei Du, Rui Su, Yuhang Chen, Kan Xu, Huan Gu, Limin Li, Piao Ma, Zhenghao Li, Hao Li
Geophysics
Scenario-conditioned flow matching for probabilistic generation of three-component ground-motion waveforms
Yi Ding, Jinjun Hu, Su Chen et al. (+5 more)
Performance-based seismic risk assessment requires three-component acceleration histories compatible with specified source, path, and site conditions. Conventional ground-motion prediction equations provide scalar intensity measures, while many generative waveform models learn amplitude and waveform shape within a single high-dimensional target. We present WaveFlowGMM, a two-stage probabilistic ground-motion model that uses peak ground acceleration (PGA) as an amplitude interface between scenario conditioning and waveform generation. The amplitude stage uses physics-informed symbolic learning to estimate component-wise PGA medians and a full cross-component covariance. The waveform stage uses few-step AlphaFlow in an invertible wavelet-packet coefficient space to generate normalised three-component histories that are rescaled by sampled PGA. Tests on an event-level NGA-West2 holdout set show that the generated motions recover the main magnitude, distance, and site scaling, keep peak and spectral residuals close to zero, preserve three-component amplitude dependence, and yield velocity and displacement histories without systematic drift after integration of the generated three-component acceleration histories. The framework provides an interpretable and computationally efficient candidate component for waveform-level seismic hazard and risk analysis.
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All authors Yi Ding, Jinjun Hu, Su Chen, Xianwei Liu, Zhongxiang Zhang, Zongchao Li, Xiaojun Li, Lili Xie
Optics
Fundamentals of Optical Fiber Sensing Schemes Based on Coherent Optical Time Domain Reflectometry: Signal Under Dynamic Temperature Conditions
Roman Ermakov, Huwei Wang, Florian Azendorf et al. (+4 more)
We present a theoretical, algorithmic, and experimental study of temperature sensing using $\phi$-OTDR with coherent detection. A physics-based model is developed to relate the measured Rayleigh backscattered signal to temperature variations along the fiber, showing that the phase
evolution encodes the cumulative temperature change between the interrogator and the sensing location, while the amplitude exhibits only local sensitivity. Based on this insight, we propose robust
algorithms for temperature-event detection and temperature-profile reconstruction. Experimental results demonstrate reliable recovery of temperature-induced perturbations in standard single-mode fibers using coherently detected $\phi$-OTDR.
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All authors Roman Ermakov, Huwei Wang, Florian Azendorf, André Sandmann, Juan M. Marin, Francesco Da Ros, Darko Zibar
Accelerator Physics
High-Power Polarization-Controlled Attosecond-Scale Soft X-ray Pulses
Zhaoheng Guo, Carlo Vicario, Andre Al Haddad et al. (+18 more)
We demonstrate a versatile platform for high-power attosecond soft X-ray pulse generation with polarization and
photon energy control at the SwissFEL free-electron
laser. An isolated high-current spike embedded within a long electron-beam pedestal emits soft X-ray pulses with single-spike spectra and multi-electronvolt bandwidths in the tunable
magnetic fields of Apple-X undulators. Demonstrated pulse parameters include a
photon energy range of 450–1070 eV, circular as well as linear polarization, and pulse energies from tens to above hundred microjoules. By tuning the longitudinal slice-dependent transverse electron beam orbit we can rapidly switch between attosecond and few femtosecond pulse length. By exploiting
magnetic chicanes in the undulator line we can produce two-colour pulse pairs with tunable delay or increase the pulse energy beyond 200~\textmu J through multi-stage amplification schemes. High-resolution longitudinal phase-space measurements and start-to-end simulations in addition to spectral measurements provide consistent evidence for attosecond-scale pulse durations. This unique combination of high pulse energy and polarization control of attosecond-scale soft X-ray pulses enables the element-specific investigations of
spin and
chiral dynamics on the natural time scale of electron motion.
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All authors Zhaoheng Guo, Carlo Vicario, Andre Al Haddad, Christopher Arrell, Andreas Dax, Umit Demirbas, Nicole Hiller, Martin Huppert, Christoph Kittel, Gregor Knopp, Eduard Prat, Sven Reiche, Antoine Sarracini, Thomas Schietinger, Kirsten Schnorr, Alexandre Trisorio, Didier Voulot, Tobias Weilbach, Hankai Zhang, Christoph Bostedt, Philipp Dijkstal
Chemical Physics
Toward a local manipulation of DNA by quantum fields
Tommaso Cenci, Riccardo Alessandro and Enrico Ronca
Hydrogen bonds are the fundamental backbone for deoxyribo-nucleic acid (DNA) stability. In this letter we propose a new strategy based on plasmonic cavities to perform a local manipulation of hydrogen bonds in DNA. The analysis is performed using state-of-the-art
Quantum Electrodynamics Coupled Cluster calculations (QED-CC). We demonstrate that in standard strong coupling regimes, small but appreciable local modifications of the nucleotide bases' interactions can be induced in a totally non-intrusive manner. The effect can eventually be enhanced if ultra-strong coupling conditions can be reached. Our strategy provides an alternative approach to methodologies based on a collective coupling to perform optical DNA manipulation.
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Plasma Physics · Cross-listed from nucl-th
Relativistic magnetohydrodynamics from kinetic theory
Khwahish Kushwah
This thesis develops a kinetic-theory framework for relativistic dissipative magnetohydrodynamics under strong electromagnetic fields, motivated by
quark-
gluon plasma in heavy-ion collisions. Starting from the relativistic Boltzmann-Vlasov equation and using the method of moments within the 14-moment approximation, it derives causal second-order hydrodynamic equations for relativistic
plasmas with increasing generality. The work first review relativistic dissipative hydrodynamics and its kinetic foundations, emphasizing the need for Israel-Stewart-type transient theories to preserve causality and stability. Electromagnetic fields are then introduced at the microscopic level, where the Lorentz force modifies the moment hierarchy and produces anisotropic transport effects absent in field-free fluids. Next, it develops relativistic dissipative magnetohydrodynamics for a non-resistive two-component
plasma of oppositely charged particles. Here, the
magnetic field couples the dissipative sectors of the two species, generating relative dissipative currents and coupled shear dynamics. For Bjorken expansion, the theory predicts damped oscillations in the transverse shear sector associated with cyclotron motion. Finally, the thesis treats the resistive two-component case, where the electric field evolves dynamically and couples to charge
diffusion and shear stress. The resulting theory reveals current-shear feedback, transient electromagnetic generation of momentum anisotropy, and underdamped dissipative oscillations. Applications to homogeneous and Bjorken-expanding
plasmas show how resistive and electromagnetic effects modify
evolution beyond standard hydrodynamics. Overall, the thesis extends relativistic dissipative hydrodynamics to magnetized and resistive
plasmas, providing a microscopic foundation for future studies of strongly magnetized
quark-
gluon plasma and astrophysical systems.
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Computational Physics · Cross-listed from quant-ph
Full-Wave Green's-Function Modeling of Collective Single-Photon Emission in Non-Markovian Open-System QED with Finite-Bandwidth Compensation of Dispersive Interactions
Hyunwoo Choi, Jisang Seo, Junwoo Gim et al. (+3 more)
This work presents a full-wave Green's function framework for modeling collective and coherent single-
photon emission from multiple
quantum emitters embedded in complex electromagnetic structures. Starting from a transverse modal completeness relation of modified Langevin noise formalism, we derive a closed set of coupled equations for population dynamics and frequency-resolved field amplitudes in the single-excitation regime. Since the electromagnetic reservoir is not traced out at the level of the dynamical amplitudes, the emitted single-
photon dynamics can be modeled within the same closed set of equations without Markovian approximation in open and dissipative environments. We demonstrate that finite-bandwidth truncation of the spectral density leads to systematic deviations in coherent dispersive interactions, even when dissipative rates appear converged. To restore causal consistency, we introduce a counter-term compensation scheme that restores the missing dispersive contributions without modifying the retained non-Markovian
memory kernel. To validate the scheme and demonstrate the practicality of the proposed framework, we present numerical examples ranging from
benchmark configurations to a three-dimensional dispersive ring-resonator structure via finite element method. These capabilities provide a practical route for rigorously incorporating full-wave electromagnetic simulations into non-Markovian multi-emitter
quantum electrodynamics, enabling predictive modeling of collective emission, coherent energy exchange, and single-
photon radiation in realistic open structures.
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All authors Hyunwoo Choi, Jisang Seo, Junwoo Gim, Bowoo Jang, Weng C. Chew, Dong-Yeop Na
Geophysics · Cross-listed from cs.LG
Probabilistic Inversion with Flow Matching
Baldur Paulwitz and Stefan Buske
We demonstrate the application of Flow Matching, a technique originating from generative Artificial Intelligence, to probabilistic inversion in geophysical settings, such as seismic Full-Waveform inversion. We adapt the well-established mathematical theory of Flow Matching from generative Artificial Intelligence to the context of probabilistic inversion. We evaluate the approach with two case studies: a simple 2D velocity model to illustrate the general features of the method, and the OpenFWI
dataset to show its capabilities for probabilistic inversion of more complex seismic velocity models.
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Fluid Dynamics
Lagrangian velocity statistics of homogeneous isotropic turbulence in dilute polymer solutions
Yusuke Koide and Susumu Goto
We conduct direct numerical simulations of homogeneous isotropic
turbulence in dilute
polymer solutions to investigate the Lagrangian velocity statistics. We show how
polymers modulate the power spectral density of the Lagrangian velocity and the Lagrangian integral timescale by varying the Reynolds number, forcing method, and
polymer relaxation time. As the
polymer relaxation time increases, the attenuation of the power spectral density extends successively from high to low frequencies, and the Lagrangian integral timescale increases. To clarify the mechanism underlying the modulation of the Lagrangian velocity statistics, we decompose the Lagrangian velocity into the contributions from
vortices at different length scales. Using this scale-decomposition analysis, we demonstrate that the observed modulation of the Lagrangian velocity statistics results from
polymer-induced suppression of
vortices that proceeds from smaller to larger scales.
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Atmospheric and Oceanic Physics
Scaling Storm-Resolving Atmospheric AI Simulation to the Entire Planet
Zeyuan Hu, Akshay Subramaniam, Noel Keen et al. (+9 more)
Kilometer-scale convection shapes precipitation extremes, tropical organization, and cloud feedbacks, but most global atmospheric models approximate these processes at 25-100 km resolution. Global storm-resolving physics models resolve convective systems explicitly, but at a cost – roughly one MWh per simulated day on exascale supercomputers – that limits long-duration simulation. We introduce STRATA (Storm-resolving Tile-based autoRegressive Atmosphere
Transformer Architecture), the first autoregressive AI emulator for global storm-resolving atmospheric dynamics. STRATA is trained on the highest-resolution atmospheric
dataset yet used for global AI emulation: 17 days of SCREAM physics-model output at 4.9-km resolution (~25 million grid
cells) sampled every 10 minutes. Our central premise is that on 10-minute timescales atmospheric dynamics are predominantly local, so training on small spatial tiles trades scarce global temporal samples for abundant local spatial samples and enables global rollout via overlapping-tile blending. STRATA combines 3D patch
embedding and local 3D neighborhood
attention, a novel Stereographic Rotary Position
Embedding (StereoRoPE) for grid-invariant encoding, and a pixel-space de-aliasing decoder that suppresses patch-scale rollout artifacts. An iso-FLOP scaling study reveals that km-scale emulation requires ~10x more FLOPs per grid point than coarse-resolution AI weather models, consistent with the higher information density of convective-scale dynamics. Trained on only 17 days of data, STRATA produces stable 24-hour global rollouts with realistic km-scale dynamics across diverse regimes, though large-scale biases develop with lead time. It achieves 48 simulation days per megawatt-hour – about 50 times better energy efficiency than the SCREAM physics model – and 741 simulated days per wall-clock day at 512 H100 GPUs. Code and
dataset are publicly available.
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All authors Zeyuan Hu, Akshay Subramaniam, Noel Keen, Tao Ge, Jaideep Pathak, Mohammad Shoaib Abbas, Suman Ravuri, Karthik Kashinath, Naser Mahfouz, Peter Caldwell, Mike Pritchard, Noah Brenowitz
Plasma Physics
Effect of externally applied resonant magnetic perturbations on resistive tearing modes
Qiming Hu, Q. Yu, Bo Rao et al. (+3 more)
Static resonant
magnetic perturbations (RMPs) generated by saddle coil current have been applied in J-TEXT tokamak experiments in order to study their effects on tearing mode instabilities. With increasing the RMP amplitude in time during the discharge, the mode stabilization is first observed, but a large locked mode follows if the RMP amplitude is increased to a too large value, indicating that the RMP amplitude is important in determining the
plasma response and the tearing mode behavior. By careful adjustment of the RMP amplitude, the (partial) stabilization of the m/n =2/1 tearing mode by RMPs of moderate amplitude has been achieved without causing mode locking (m and n are the poloidal and toroidal mode numbers). To compare with experimental results, nonlinear numerical modeling based on reduced MHD equations has been carried out. With experimental parameters as input, both the mode locking and mode stabilization by RMPs are also obtained from numerical modeling. Further calculations have been carried out to study the
plasma parameters affecting the mode stabilization by RMPs, including the
plasma rotation frequency, viscosity, Alfvén velocity, and the RMPs amplitude. It is found that the suppression of the tearing mode by RMPs of moderate amplitude is possible for a sufficiently high ratio of
plasma rotation velocity to the Alfvén speed. A larger
plasma viscosity enhances the mode stabilization.
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All authors Qiming Hu, Q. Yu, Bo Rao, Yonghua Ding, Xiwei Hu, Ge Zhuang
Applied Physics · Cross-listed from eess.SY
FPGA-based LQG controller and hardware-in-the-loop simulator implementation for nanomechanical systems
Vojtěch Mlynář, Johannes Berndorfer, Andreas Kugi et al. (+1 more)
We present an open-source framework for real-time Linear Quadratic Gaussian (LQG) control and hardware-in-the-loop (HIL) simulation on the affordable Red Pitaya STEMlab FPGA platform. The controller implements a discrete-time Kalman filter and Linear Quadratic Regulator (LQR) for systems with up to three coupled oscillatory degrees of freedom, targeting applications in levitated optomechanics, MEMS/NEMS, and related experimental platforms. Complementing the controller, the HIL simulator provides a~configurable second-order
stochastic plant with nonlinear input and output mappings, enabling realistic closed-loop testing under real-time and fixed-point constraints. A MATLAB-based workflow automates model configuration, controller synthesis, numerical scaling, and FPGA deployment without requiring specialized hardware expertise. As an end-to-end demonstration, we present the stabilization of a levitated nanoparticle in a two-dimensional double-well potential, illustrating the complete workflow from model definition and simulation to real-time feedback control.
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All authors Vojtěch Mlynář, Johannes Berndorfer, Andreas Kugi, Andreas Deutschmann-Olek
Optics
Unresolved-Sideband Optomechanics with Hexagonal Boron Nitride: Induced Transparency, Gain, and Frequency Combs
Francesco Fogliano, Thibaud Ruelle, David Jaeger et al. (+1 more)
Optomechanically induced transparency (OMIT) is usually modeled and studied in the resolved-sideband regime, but many compact microcavity platforms operate in the unresolved-sideband limit $(\kappa \gg \Omega_m)$. Here we investigate OMIT in this regime using a tunable fiber-based Fabry-Perot microcavity coupled to a suspended hexagonal boron nitride (hBN) drum resonator in a membrane-in-the-middle geometry. The system achieves a large single-
photon coupling rate of $g_0/2\pi \sim 180$ kHz and exhibits strong radiation-pressure backaction. By measuring OMIT spectra as a function of pump power and cavity detuning, we observe a crossover from a transparency-like dip to a gain feature in the reflected response. These maps are quantitatively reproduced by the full linearized optomechanical response, demonstrating the breakdown of the standard rotating-wave approximation used in the resolved-sideband limit. Finally, we drive the system into a nonlinear regime to generate optomechanical frequency combs. These results establish hBN fiber-cavities as a versatile architecture for unresolved-sideband optomechanics, nonlinear dynamics, and hybrid device integration.
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All authors Francesco Fogliano, Thibaud Ruelle, David Jaeger, Martino Poggio