Atmospheric and Oceanic Physics
Tidal motions in the deep Mediterranean
Hans van Haren
The Mediterranean Sea is known for its limited
tidal motions. For example, surface barotropic
tidal elevations have an amplitude of 0.1 m in the Northwestern Mediterranean. Nevertheless, these small tides are noticeable in temperature records at the 2500-m deep seafloor, but only under near-homogeneous conditions when buoyancy frequency N < f, the inertial frequency. After transfer of pressure to temperature units via the local adiabatic lapse rate, the observed internal-wave temperature signals may thus be corrected for 1.5x10-5-degrC amplitude semidiurnal barotropic tides. The remaining baroclinic tides are embedded in the broad and featureless inertio-
gravity wave band, with some energy enhancement near its boundaries, also under tenfold-larger energetic stratified water conditions.
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Optics
DNA-Origami-Assembled Rhodium Nanoantennas for Deep-UV Label-Free Single-Protein Detection
Nicco Corduri, Malavika Kayyil Veedu, Yifan Yu et al. (+6 more)
Nanoparticles of plasmonic metals have significantly to the development of spectroscopic techniques, enabling strong confinement of electromagnetic fields at the nanoscale and corresponding signal amplification. However, to date, plasmonic applications have been limited mainly to the visible and near-infrared range, as materials supporting ultraviolet resonances typically exhibit poor chemical stability and lack robust surface functionalisation methods. In this work, we address these limitations by introducing a fully programmable approach to UV plasmonics based on rhodium nanocube dimers assembled using DNA origami templates. We have developed a reliable ligand exchange strategy that allows the functionalisation of rhodium nanocubes with DNA while maintaining their colloidal stability. These DNA-modified nanocubes act as modular building blocks that can be assembled into dimers with 69% efficiency and an average gap size of 10 nm. The DNA origami design also allows for the deterministic placement of a single streptavidin
protein in the plasmonic gap, unlike previous methods based on
stochastic diffusion. Experiments with single-molecule autofluorescence in UV, supported by numerical simulations, show an increase in brightness of up to 22, a reduction in fluorescence lifetime, and a more than tenfold increase in the total number of detected
photons. By creating a robust and versatile platform for the production of UV-resonant plasmonic nanoantennas, this work extends the functionality of plasmonics to the deep UV spectrum and opens up new possibilities for labelling-free single-
protein spectroscopy.
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All authors Nicco Corduri, Malavika Kayyil Veedu, Yifan Yu, Yanqiu Zou, Jie Liu, Denis Garoli, Guillermo P. Acuna, Jérôme Wenger, Karol Kołątaj
Chemical Physics
Mechanistic Insights into Chemical Exchange during the Signal Amplification by Reversible Exchange Sensitization of Pyruvate
Charbel D. Assaf, Vladimir V. Zhivonitko, Amaia Vicario et al. (+4 more)
Signal amplification by reversible exchange (SABRE) is a
nuclear spin hyperpolarization technique in which the transient interaction of parahydrogen (pH2) and a target substrate with an iridium complex leads to polarization transfer to the substrate. Here, we use a parahydrogen-enhanced,
spin-selective NMR method to investigate pyruvate binding, which is combined with exchange-model fitting and DFT calculations. Our study reveals several key findings that reshape the current understanding of SABRE: (a) intramolecular hydrogen exchange of the hydrides, occurring faster than pyruvate or H2 loss; (b) the discovery of a novel stable [Ir(H)2(IMes)(ąppa}1-pyr)(DMSO)2] complex; and (c) the potential role of counterions (here Na+) in Ir-pyruvate binding. Previously unknown insights into complex kinetics and distributions as a function of temperature, [DMSO], [pyruvate], and hydrogen pressure are presented. The methods demonstrated here, exemplified by SABRE, provide a framework that is expected to guide future research in the field.
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All authors Charbel D. Assaf, Vladimir V. Zhivonitko, Amaia Vicario, Alexander A. Auer, Simon B. Duckett, Jan-Bernd Hövener, Andrey N. Pravdivtsev
Applied Physics · Cross-listed from cond-mat.mes-hall
Electric-current control of anomalous Hall effect
Jianping Guo, Gusthavo M. S. Brizolla, Peng Rao et al. (+10 more)
We demonstrate robust and reversible electric-current control of the anomalous
Hall effect (AHE) in a two-dimensional WTe2/Fe3GeTe2 (FGT) stack. Applying a current through Td-WTe2 leads to a
giant modulation of the AHE of the adjacent FGT layer, with the relative change of the AHE conductivity exceeding 180%. Control experiments show that i) the observed effect is absent in pure FGT, ii) the modulation weakens in thicker FGT films, confirming its interfacial origin, and iii) the modulation peaks for
bilayer WTe2, indicating that the Berry-
curvature dipole (BCD) plays the dominant role in the modulation. We propose that the charge current I generates an out-of-plane magnetization Mz via BCD in WTe2 and Mz modifies the exchange splitting of FGT via the inverse
magnetic proximity effect, thereby altering its Berry
curvature and nontrivially influencing the AHE. The demonstrated method of AHE control offers new possibilities for magnetism control, i.e., for the study of AHE-transistors as well as electric-current control of
quantum magnets, especially
magnetic insulators.
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All authors Jianping Guo, Gusthavo M. S. Brizolla, Peng Rao, Jian Shao, X. H. Huang, Thomas N. G. Meier, Tailai Xu, Peirui Ji, Jonathan Finley, Jaroslav Fabian, Johannes Knolle, Christian Back, Lin Chen
Fluid Dynamics
Most probable path and invariant sets in noise-induced transition to turbulence
Yoshiki Hiruta, Kento Yasuda and Kenta Ishimoto
Turbulence transition often arises from a subcritical transition between bistable states characterized by invariant sets of deterministic dynamical systems, and such transitions can be triggered by system noise as rare events. In this study, we employ the Onsager-Machlup (OM) formulation of
stochastic dynamics to examine the Hamilton equations governing the most probable transition paths (MPPs). We introduce an effective potential function, termed the OM potential, which depends on the noise strength. Focusing on the Dauchot-Manneville model as a minimal system with an edge state, we comprehensively analyze the MPP between laminar and turbulent states for different transition times. We find that the MPPs cross the separatrix at nearly the same point regardless of the transition time, and the obtained OM action values suggest that the transition to
turbulence occurs more frequently than the transition to the laminar state. Moreover, we numerically demonstrate that the noise-induced transition paths follow the OM potential landscape and its bifurcation diagram, indicating that the qualitative behavior of the MPPs is determined by the OM potential. Our methodology formulated in general dynamical systems provides a theoretical basis for predicting noise-induced transitions among invariant sets of the dynamics.
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Optics · Cross-listed from cs.CV
Towards Real-world Lens Active Alignment with Unlabeled Data via Domain Adaptation
Wenyong Li, Qi Jiang, Weijian Hu et al. (+5 more)
Active
Alignment (AA) is a key technology for the large-scale automated assembly of high-precision optical systems. Compared with labor-intensive per-model on-device calibration, a digital-twin pipeline built on optical simulation offers a substantial advantage in generating large-scale labeled data. However, complex imaging conditions induce a domain gap between simulation and real-world images, limiting the generalization of simulation-trained models. To address this, we propose augmenting a simulation baseline with minimal unlabeled real-world images captured at random misalignment positions, mitigating the gap from a domain adaptation perspective. We introduce Domain Adaptive Active
Alignment (DA3), which utilizes an autoregressive domain transformation generator and an
adversarial-based feature
alignment strategy to distill real-world domain information via self-supervised learning. This enables the extraction of domain-invariant image degradation features to facilitate robust misalignment prediction. Experiments on two lens types reveal that DA3 improves accuracy by 46% over a purely simulation pipeline. Notably, it approaches the performance achieved with precisely labeled real-world data collected on 3 lens samples, while reducing on-device data collection time by 98.7%. The results demonstrate that domain adaptation effectively endows simulation-trained models with robust real-world performance, validating the digital-twin pipeline as a practical solution to significantly enhance the efficiency of large-scale optical assembly.
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All authors Wenyong Li, Qi Jiang, Weijian Hu, Kailun Yang, Zhanjun Zhang, Wenjun Tian, Kaiwei Wang, Jian Bai
Atomic Physics
Electron capture induced fragmentation of CO$_2^{3+}$: Influence of projectile charge on sequential and concerted break-up pathways
Akash Srivastav, Sumit Srivastav and Bhas Bapat
We investigate the $\text{O}^+:\text{C}^+:\text{O}^+$ fragmentation channel of CO$_2^{3+}$ produced in slow collisions with Ar$^{q+}$ projectiles ($4 \le q \le 16$, velocities $\approx 0.3$ a.u). Using the native-frames method, we disentangle the sequential and concerted break-up processes and their corresponding kinetic energy release (KER) distributions. Ab initio potential energy curves of CO$_2^{3+}$ are calculated and mapped to the KER spectra to identify the underlying electronic states involved in the fragmentation. While the sequential KER distributions remain nearly unchanged for across the projectile charge range, the concerted KER distributions exhibit pronounced but non-systematic variations with projectile charge. In addition, a low KER feature around 15.5 eV – previously associated with sequential break-up in electron and
proton impact – is observed for Ar$^{4+}$ impact and, to a lesser extent, for Ar$^{6+}$ impact. It originates predominantly from concerted break-up of the low-lying $^2\Pi_\text{g}$ and $^{2,4}\Pi_\text{u}$ states. Branching ratios of the two break-up pathways deviate from simple monotonic trends for certain projectiles, but barring these exceptions, the fraction of concerted break-up decreases with increasing $q$, while that for sequential break-up increases. These findings underscore the necessity of accounting for the detailed electronic structure of the projectile, rather than its charge alone, to achieve a comprehensive understanding of collisional dynamics in slow, highly charged ion collisions.
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Chemical Physics · Cross-listed from cs.LG
A Pre-trained Reaction Embedding Descriptor Capturing Bond Transformation Patterns
Weiqi Liu, Fenglei Cao, Yuan Qi et al. (+1 more)
With the rise of data-driven reaction prediction models, effective reaction descriptors are crucial for bridging the gap between real-world chemistry and digital representations. However, general-purpose, reaction-wise descriptors remain scarce. This study introduces RXNEmb, a novel reaction-level descriptor derived from RXNGraphormer, a model pre-trained to distinguish real reactions from fictitious ones with erroneous bond changes, thereby learning intrinsic bond formation and cleavage patterns. We demonstrate its utility by data-driven re-clustering of the USPTO-50k
dataset, yielding a classification that more directly reflects bond-change similarities than rule-based categories. Combined with dimensionality reduction, RXNEmb enables visualization of reaction space diversity. Furthermore,
attention weight analysis reveals the model's focus on chemically critical sites, providing mechanistic insight. RXNEmb serves as a powerful, interpretable tool for reaction fingerprinting and analysis, paving the way for more data-centric approaches in reaction analysis and discovery.
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All authors Weiqi Liu, Fenglei Cao, Yuan Qi, Li-Cheng Xu
Optics
Radiation processes in dielectric cylindrical waveguides
A.A. Saharian, L.Sh. Grigoryan and H.F. Khachatryan
Dielectric cylindrical waveguides are widely used for confining and guiding of electromagnetic waves in relatively wide range of frequencies. They have found numerous technological and scientific applications in telecommunications, medicine, material science, photonics and
quantum optics. The electromagnetic field Green function is the central object in investigations of different types of radiation processes in those structures. In this paper, we review and further develop the recurrence procedure for evaluating the electromagnetic field Green function in a medium made of any number of homogeneous cylindrical layers. The general results are specified for a cylindrical waveguide immersed in a homogeneous medium. Expressions are provided for all the components of the Green tensor in both regions inside and outside the cylinder. As an application of the results for the Green function, we consider the radiation of a charged particle rotating around a dielectric cylinder. The intensities for all types of radiation processes are discussed. They include the synchrotron-Cherenkov radiation at large distances from the cylinder and the radiation on guided and surface polaritonic modes confined inside or near the surface of the cylinder. The paper provides explicit formulas for the electromagnetic fields and the spectral-angular densities of those radiations. It also includes a numerical and comparative analysis.
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Physics and Society · Cross-listed from q-bio.PE
Integrated strong reciprocity enables productive punishment and protective defection
Tatsuya Sasaki and Satochi Uchida
Cooperation in large groups and one-shot interactions is often hindered by freeloading. Punishment can enforce cooperation, but it is usually regarded as wasteful because the costs of punishing offset its benefits. Here, we analyze an evolutionary game model that integrates upstream and downstream reciprocity with costly punishment: integrated strong reciprocity (ISR). We demonstrate that ISR admits a stable mixed
equilibrium of ISR and unconditional defection (ALLD), and that costly punishment can become productive: When sufficiently efficient, it raises collective welfare above the no-punishment baseline. ALLD players persist as evolutionary shields, preventing invasion by unconditional cooperation (ALLC) or alternative conditional strategies (e.g., antisocial punishment). At the same time, the mixed
equilibrium of ISR and ALLD remains robust under modest complexity costs that destabilize other symmetric cooperative systems.
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Biological Physics
Roadmap for Condensates in Cell Biology
Dilimulati Aierken, Sebastian Aland, Stefano Bo et al. (+38 more)
Biomolecular condensates govern essential cellular processes yet elude description by traditional
equilibrium models. This roadmap, distilled from structured discussions at a workshop and reflecting the consensus of its participants, clarifies key concepts for researchers, funding bodies, and journals. After unifying terminology that often separates disciplines, we outline the core physics of condensate formation, review their biological roles, and identify outstanding challenges in nonequilibrium theory, multiscale simulation, and quantitative in-
cell measurements. We close with a forward-looking outlook to guide coordinated efforts toward predictive, experimentally anchored understanding and control of biomolecular condensates.
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All authors Dilimulati Aierken, Sebastian Aland, Stefano Bo, Steven Boeynaems, Danfeng Cai, Serena Carra, Lindsay B. Case, Hue Sun Chan, Jorge R. Espinosa, Trevor K. GrandPre, Alexander Y. Grosberg, Ivar S. Haugerud, William M. Jacobs, Jerelle A. Joseph, Frank Jülicher, Kurt Kremer, Guido Kusters, Liedewij Laan, Keren Lasker, Katrin S. Laxhuber, Hyun O. Lee, Kathy F. Liu, Dimple Notani, Yicheng Qiang, Paul Robustelli, Leonor Saiz, Omar A. Saleh, Helmut Schiessel, Jeremy Schmit, Meng Shen, Krishna Shrinivas, Antonia Statt, Andres R. Tejedor, Tatjana Trcek, Christoph A. Weber, Stephanie C. Weber, Ned S. Wingreen, Huaiying Zhang, Yaojun Zhang, Huan Xiang Zhou, David Zwicker
Fluid Dynamics
A Minimal Thermo-Fluid Model for Pressure-Driven Extraction in a Moka Pot
Syahril Siregar
The moka pot provides a familiar example of a thermally driven flow system in which heating, vapor pressure generation, and fluid extraction are strongly coupled. We present a minimal, dimensionless dynamical model describing the
evolution of temperature, pressure, and extracted volume during moka pot brewing. The model consists of a small set of coupled ordinary differential equations incorporating constant heating, heat loss, vapor pressure buildup, and pressure-driven flow through the coffee bed. The heating stage of the model is quantitatively compared with published experimental temperature time data, allowing the characteristic thermal timescale to be fixed independently. Using the experimentally constrained temperature
evolution as input, the model predicts the pressure rise and identifies the onset of extraction without additional fitting parameters. Despite its simplicity, the model exhibits several qualitatively distinct extraction regimes, including delayed onset of flow, smooth extraction, and rapid extraction driven by nonlinear feedback between temperature and pressure. These regimes are governed by a small number of dimensionless parameters with clear physical interpretation. Rather than providing detailed quantitative predictions for specific devices, the model is intended as a transparent pedagogical framework for illustrating how physicists construct, simplify, and test coupled thermo-fluid models using experimentally accessible data in an everyday physical system in an everyday physical context.
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Chemical Physics
Simultaneous Learning of Static and Dynamic Charges
Philipp Stärk, Henrik Stooß, Marcel F. Langer et al. (+4 more)
Long-range interactions and electric response are essential for accurate modeling of condensed-phase systems, but capturing them efficiently remains a challenge for atomistic machine learning. Traditionally, these two phenomena can be represented by static charges, that participate in Coulomb interactions between atoms, and dynamic charges such as atomic polar tensors - aka Born effective charges - describing the response to an external electric field. We critically compare different approaches to learn both types of charges, taking bulk water and water clusters as paradigmatic examples: (1) Learning them independently; (2) Coupling static and dynamic charges based on their physical relationship with a single global coupling constant to account for dielectric screening; (3) Coupled learning with a local, environment-dependent screening factor. In the coupled case, correcting for dielectric screening is essential, yet the common assumption of homogeneous, isotropic screening breaks down in heterogeneous systems such as water clusters. A learned, environment-dependent screening restores high accuracy for the dynamical charges. However, the accuracy gain over independent dynamic predictions is negligible, while the computational cost increases compared to using separate models for static and dynamical charges. This suggests that, despite the formal connection between the two charge types, modeling them independently is the more practical choice for both condensed-phase and isolated cluster systems.
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All authors Philipp Stärk, Henrik Stooß, Marcel F. Langer, Egor Rumiantsev, Alexander Schlaich, Michele Ceriotti, Philip Loche
Optics
First Thin-Film Lithium Tantalate Polarization Controller Enabling Reset-Free Mrad/s Tracking for Optical Interconnects
Zichao Gao, Siyu Lu, Mingming Zhang et al. (+16 more)
The rapid escalation of computing power driven by large-scale artificial intelligence is placing unprecedented demands on the bandwidth, latency, and energy efficiency of data-center interconnects (DCIs). Self-homodyne coherent (SHC) transmission is a promising architecture because it preserves the spectral efficiency of coherent detection while greatly simplifying digital signal processing, but its practical deployment is critically limited by random and often ultrafast state-of-polarization (SOP) fluctuations that induce carrier fading and destabilize coherent reception. Here we report the first integrated polarization controller based on thin-film lithium tantalate (TFLT), enabling reset-free polarization tracking at Mrad/s speeds. The four-stage electro-optic device exhibits polarization-dependent loss (PDL) below 0.3 dB, a half-wave voltage below 2.5 V, high modulation bandwidth, and negligible DC drift. To accommodate the finite tuning range of integrated phase shifters, we develop a finite-boundary gradient-descent (FBGD) control
algorithm that ensures reset-free SOP
evolution with no phase jump. The implemented adaptive polarization controller (APC) is validated through both standalone polarization-tracking measurements and a dual-polarization 16-QAM SHC 400-Gbps transmission system. Transient polarization disturbances can be tracked at speeds up to 2 Mrad/s, while stable reset-free operation under continuous polarization disturbances is maintained up to 1 Mrad/s. This reset-free performance represents more than doubling the state of the art, while the pre-FEC bit-error rates remain below the HD-FEC threshold under realistic DCI conditions and lightning-scale polarization disturbances. These results establish TFLT as a new platform for ultrafast, low-power, reset-free, and drift-free polarization control in coherent optical interconnects and beyond.
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All authors Zichao Gao, Siyu Lu, Mingming Zhang, Gengqi Yao, Chicheng Zhang, Miao Deng, Siyu Chen, Yiqi Dai, Shiqi Yue, Chijun Li, Yuqi Li, Ziwen Zhou, Zheli Liu, Xinyang Yu, Xitao Ji, Cheng Zeng, Siqi Yan, Jinsong Xia, Ming Tang
Space Physics · Cross-listed from astro-ph.SR
Investigating the Center-to-Limb Effects in Helioseismic Data Using 3D Radiative Hydrodynamic Simulations
Irina N. Kitiashvili
Full-disk observations from missions such as the SDO and SOHO have enabled comprehensive studies of
solar oscillations and dynamics. Interpreting helioseismic and photospheric data is complicated by systematic center-to-limb variations. To explore the physical origin of these variations, we perform local 3D radiative hydrodynamic simulations that include effects of
solar rotation to generate 24-hour synthetic time series of continuum intensity and Doppler velocity for nine viewing angles spanning from $-75^{\circ}$ to $75^{\circ}$. The simulations reveal a systematic decrease in 1D oscillation power toward the limbs and a pronounced East-West asymmetry that increases with frequency, primarily due to rotation-induced flows. Analysis of $\ell-\nu$ diagrams shows a decrease in the amplitude and width of the surface
gravity ($f$) and resonant pressure ($p$) modes with increasing angular distance from the disk center. The amplitudes of the corresponding pseudo-modes with frequencies above the acoustic cut-off frequency increase in the intensity power spectra and are suppressed in the velocity spectra. The ring-diagram analysis of the simulation data further demonstrates anisotropic broadening of the modes, and the impact of the foreshortening effect on the energy distribution, and distinct differences in background noise and pseudo-mode structure between the intensity and velocity data. These results indicate that the center-to-limb effects arise from both
geometric projection and physical factors such as line-formation height and potential effects of the radial differential rotation. The findings provide a framework for correcting helioseismic observations and demonstrate that realistic simulations are a powerful tool for disentangling
geometric and physical biases in
solar data.
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Space Physics
On flying near the base of a pseudo-streamer
Forrest Mozer, Oleksiy Agapitov, Kyungeun Choi et al. (+1 more)
Near the 10
solar radius perihelion of Parker
Solar Probe encounter 24, a confined region containing an enhanced
plasma density (25,000 per cubic centimeter) and broadband electrostatic waves was encountered. The
solar wind velocity (200 kilometers per second) and ion temperature (25 electron Volts) were significantly reduced as compared to their values in the ambient
solar wind. Because the polarity of the radial
magnetic field did not change sign on the two sides of the crossing and the crossed region contained a double-peaked
plasma structure, the spacecraft must have passed near the base of a pseudo-streamer. In the
plasma frame, an electric field as large as 400 millivolts per meter was detected during the crossing. This field is not associated with an ExB drift because it is observed in the
plasma rest frame. Instead, it is balanced by the Generalized Ohm's Law terms whose current dependent term associated with this electric field was less than 1 milliampere per square meter, corresponding to a drift velocity less than 2.5 kilometers per second. The region also contained a turbulent
plasma with density fluctuations as large as 0.3, suggesting that the resistive term in the Generalized Ohm's Law could be significant. In addition, both the density and electric field had non-zero slopes as functions of time, suggesting that the pressure gradient term in the Generalized Ohm's Law also mattered. This large electric field in the
plasma rest frame may be the first and largest such field ever reported.
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All authors Forrest Mozer, Oleksiy Agapitov, Kyungeun Choi, Andrii Voshchepynets
Fluid Dynamics
A Simple but Efficient Transformer-Based Physics-Informed Neural Network for Incompressible Navier–Stokes Equations
Biswanath Barman, Debdeep Chatterjee and Rajendra K. Ray
Traditional computational fluid dynamics and physics-informed neural networks (PINNs) often suffer from high computational cost, mesh sensitivity, and reduced accuracy for strongly nonlinear and time-dependent flows. To address these limitations, we propose PhysicsFormer, a simple and efficient
Transformer-based physics-informed neural network framework for complex fluid flow simulations. The proposed architecture employs encoder–decoder multi-head
attention to capture long-range temporal dependencies and enhance spatio-temporal information propagation. Unlike conventional multilayer perceptron-based PINNs, PhysicsFormer utilizes pseudo-sequential spatio-temporal representations together with a dynamics-weighted loss formulation to improve convergence, stability, and predictive accuracy. Owing to its lightweight architecture and parallel learning strategy, the proposed framework achieves faster training and lower computational cost than existing
Transformer-based PINN models. The performance of the proposed framework is demonstrated on the convection equation, Burgers' equation, lid-driven cavity flow at $Re=100$, and inverse Navier–Stokes and flow reconstruction problems for flow past a circular cylinder at $Re=100$ and $Re=3900$. For the inverse Navier–Stokes problem at $Re=100$, the proposed framework simultaneously reconstructs the flow field and identifies governing equation parameters with nearly $0\%$ absolute error under both clean and noisy data conditions. Furthermore, for the high-Reynolds-number case at $Re=3900$, PhysicsFormer accurately reconstructs the velocity and pressure fields using only $25$ spatial measurements per snapshot over $100$ temporal snapshots. The obtained results demonstrate that PhysicsFormer provides an accurate, robust, and computationally efficient framework for complex time-dependent fluid flow problems.
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Biological Physics · Cross-listed from cond-mat.stat-mech
Interplay of activity and non-reciprocity in tracer dynamics: From non-equilibrium fluctuation-dissipation to giant diffusion
Subhajit Paul, Manish Patel and Debasish Chaudhuri
Non-reciprocal interactions play a key role in shaping transport in active and passive systems, giving rise to striking nonequilibrium behavior. Here, we study the dynamics of a tracer – active or passive – embedded in a bath of active or passive particles, coupled through non-reciprocal interactions. Starting from the microscopic
stochastic dynamics of the full system, we derive an overdamped generalized Langevin equation for the tracer, incorporating a non-Markovian
memory kernel that captures bath-mediated correlations. This framework allows us to compute the tracer's velocity and displacement response, formulate a generalized nonequilibrium fluctuation-dissipation relation, and determine the mean-squared displacement (MSD). We find that while the MSD becomes asymptotically diffusive, the effective diffusivity depends non-monotonically on the degree of non-reciprocity and exhibits a pronounced enhancement near a resonance set by the number of bath particles. We refer to this regime as
giant diffusivity. We further show that this enhanced transport is accompanied by a strong increase in heat dissipation, revealing a direct thermodynamic cost of non-reciprocal transport. Our analytical predictions are supported by numerical simulations, including systems with short-range interactions, demonstrating the robustness of
giant diffusivity and highlighting experimentally accessible signatures of non-reciprocal interactions in soft materials.
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Optics
Upstream Laser-based Longitudinal Enhancement of Relativistic Photoelectrons
Hao Zhang, Randy Lemons, Jack Hirschman et al. (+23 more)
Controlling the longitudinal phase space of high-brightness relativistic electron beams is crucial for advancing a broad spectrum of charged-particle-based instrumentation and scientific frontiers. A generalized method for achieving this control involves manipulating the photoemission
laser's temporal distribution at the picosecond level, a long-standing technical challenge. Recent developments in
laser shaping have enabled the creation of high-power, picosecond-scale symmetrical and asymmetrical temporal profiles, capable of fine-tuning complex space-charge dynamics and external field effects in relativistic charged-particle beams. Here, we demonstrate that rather than deviations from theorized, idealized
laser distributions, a controlled asymmetry can be harnessed to counteract accelerator-induced distortions. By implementing spatiotemporal shaping of the ultraviolet photocathode
laser at the LCLS-II superconducting injector, we achieve deterministic control over the longitudinal phase space without downstream corrections. We find that this optical asymmetry induces a self-linearizing effect across both low (40 pC) and high (80 pC) charge regimes, effectively suppressing nonlinear compression and energy chirp. Consequently, this approach is expected to preserve a low emittance comparable to that of ideal flattop or regular Gaussian profiles, while delivering superior current uniformity and shot-to-shot stability. These results establish spatiotemporal
laser shaping as a compact, generalizable tool for directly optimizing beam brightness at the source.
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All authors Hao Zhang, Randy Lemons, Jack Hirschman, Nicole Neveu, Nicolas Sudar, River Robles, Paris Franz, David Cesar, Zihan Zhu, Mathew Britton, Kurtis Borne, Zhen Zhang, Kirk A. Larsen, Benjamin Mencer, Justin Baker, Chad Pennington, Razib Obaid, Yuantao Ding, Ryan Coffee, Gabriel Just, Feng Zhou, Ji Qiang, James Cryan, Joseph Robinson, Agostino Marinelli, Sergio Carbajo
History and Philosophy of Physics · Cross-listed from quant-ph
Local Scale Invariance in Quantum Theory: A Non-Hermitian Pilot-Wave Formulation
Indrajit Sen and Matthew Leifer
We show that Weyl's abandoned idea of local scale invariance has a natural realization at the
quantum level in pilot-wave (de Broglie-Bohm) theory. We obtain the Weyl covariant derivative by complexifying the electromagnetic gauge coupling parameter. The resultant non-hermiticity has a natural interpretation in terms of local scale invariance in pilot-wave theory. The conserved current density is modified from $|\psi|^2$ to the local scale invariant, trajectory-dependent ratio $|\psi|^2/ \mathbf 1^2[\mathcal C]$, where $\mathbf 1[\mathcal C]$ is a scale factor that depends on the pilot-wave trajectory $\mathcal C$ in configuration space. All physical predictions are local scale invariant, even in the presence of mass terms. Our approach is general, and we implement it for the Schrödinger and Pauli equations, and for the Dirac equation in curved spacetime, each coupled to an external electromagnetic field. We also implement it in
quantum field theory for the case of a quantized
axion field interacting with a quantized electromagnetic field. We discuss the
equilibrium probability density and show that the corresponding trajectories are unique. Our results provide a pivotal understanding of local scale invariance in
quantum theory.
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Physics and Society
A disease-spread model on hypergraphs with distinct droplet and aerosol transmission modes
Tung D. Nguyen and Mason A. Porter
We examine the spread of an infectious disease, such as one that is caused by a respiratory virus, with two distinct modes of transmission. To do this, we consider a susceptible–infected–susceptible (SIS) disease on a hypergraph, which allows us to incorporate the effects of both dyadic (i.e., pairwise) and polyadic (i.e., group) interactions on disease propagation. This disease can spread either via large droplets through direct social contacts, which we associate with edges (i.e., hyperedges of size 2), or via infected aerosols in the environment through hyperedges of size at least 3 (i.e., polyadic interactions). We derive mean-field approximations of our model for two types of hypergraphs, and we obtain threshold conditions that characterize whether the disease dies out or becomes endemic. Additionally, we numerically simulate our model and a mean-field approximation of it to examine the impact of various factors, such as hyperedge size (when the size is uniform), hyperedge-size distribution (when the sizes are nonuniform), and hyperedge-recovery rates (when the sizes are nonuniform) on the disease dynamics.
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Instrumentation and Detectors
muT2-NMR: Micro-Scale Correlation Relaxometry for in-situ High-Pressure Nuclear Magnetic Resonance
Thomas Meier, Meng Yang, Yishan Zhou et al. (+6 more)
Over the last decade, frequency-domain in-situ high-pressure
nuclear magnetic resonance (NMR) spectroscopy in diamond anvil
cells (DACs) has been employed as a structural and electronic probe of condensed matter systems at pressures well into the megabar range. However, extensive
spin interactions and sample heterogeneities under pressure often lead to significant spectral overlap, inhibiting independent observation of chemically similar
spin sub-species in the same sample. In this work, we introduce a time-domain relaxometry framework specifically suited for DAC experiments, named muT2-NMR. Experimental flexibility and operational robustness are benchmarked on three hydrogen-rich molecular solids at pressures up to 72 GPa. We demonstrate that muT2-NMR can resolve individual molecular subunits in relaxation space, paving the way for novel high-pressure, high-resolution NMR applications in molecular solids.
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All authors Thomas Meier, Meng Yang, Yishan Zhou, Yunhua Fu, Rui Zhang, Ziliang Wang, Tianyao Zheng, Rajesh Jana, Takeshi Nakagawa
Data Analysis and Statistics · Cross-listed from q-bio.NC
A Quantifiable Information-Processing Hierarchy Provides a Necessary Condition for Detecting Agency
Brett J. Kagan, Valentina Baccetti, Brian D. Earp et al. (+3 more)
As intelligent systems are developed across diverse substrates - from machine learning models and neuromorphic hardware to in vitro neural cultures - understanding what gives a system agency has become increasingly important. Existing definitions, however, tend to rely on top-down descriptions that are difficult to quantify. We propose a bottom-up framework grounded in a system's information-processing order: the extent to which its transformation of input evolves over time. We identify three orders of information processing. Class I systems are reactive and memoryless, mapping inputs directly to outputs. Class II systems incorporate internal states that provide
memory but follow fixed transformation rules. Class III systems are adaptive; their transformation rules themselves change as a function of prior activity. While not sufficient on their own, these dynamics represent necessary informational conditions for genuine agency. This hierarchy offers a measurable, substrate-independent way to identify the informational precursors of agency. We illustrate the framework with neurophysiological and computational examples, including thermostats and receptor-like memristors, and discuss its implications for the ethical and functional evaluation of systems that may exhibit agency.
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All authors Brett J. Kagan, Valentina Baccetti, Brian D. Earp, J. Lomax Boyd, Julian Savulescu, Adeel Razi