Optics
Broadband dielectric permittivity tensor of muscovite for next-generation all van der Waals photonic components
Meri Hayrapetyan, Maksim Sargsyan, David Karakhanyan et al. (+8 more)
We report a comprehensive determination of the broadband dielectric permittivity tensor of van der Waals (vdW) muscovite also referred to as mica, establishing it as a low-index low-loss platform for ultrathin nanophotonics. Resolving its anisotropic vibrational response and extracting accurate tensor components across broadband ultraviolet (UV) to near-infrared (NIR) spectral region, we show that vdW muscovite exhibits consistently low refractive indices negligible extinction and weak in-plane anisotropy allowing its effective treatment as a uniaxial dielectric in thin-film limits. Leveraging these properties, we design muscovite based vdW
heterostructures pairing it MoS2, engineering few-layer distributed Bragg reflectors (DBR) and dichroic beam splitters (DBS) with high efficiency robust optical performance in a broad NIR spectral region achieved with sub-micron thicknesses. Our findings spotlight the high significance of low-index extinctionless vdW
crystals, positioning muscovite as a highly perspective atomically flat building block for next-generation, broadband, all-vdW nanophotonic components.
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All authors Meri Hayrapetyan, Maksim Sargsyan, David Karakhanyan, Ani Khachatryan, Maria Levonyan, Dmitrii Litvinov, Maciej Koperski, Artsruni Margaryan, Makars Šiškins, Kostya S. Novoselov, Davit A. Ghazaryan
Fluid Dynamics
The evolution of a gas current injected into a curved axisymmetric porous channel
Peter Castellucci, Radha Boya, Lin Ma et al. (+2 more)
We investigate gas injection into axisymmetric water-saturated porous channels with Gaussian and
parabolic profiles, as idealized models of underground gas storage in dome-shaped anticlines. Exploiting the slenderness of each channel, we derive an
evolution equation for the gas/
liquid interface using a composite asymptotic approximation that accommodates large channel slopes and has a simplified small-slope form describing spreading in weakly curved channels. In the high gas-mobility limit, in contrast with flat planar channels, buoyancy influences the dynamics through different mechanisms in each geometry. For gas injected steadily into a Gaussian channel, buoyancy can continually affect the flow due to the attenuation of the gas velocity caused by axisymmetry. In
parabolic channels, the increasing channel slope ensures that buoyancy eventually influences the flow, at a timescale depending on injection rate and fluid properties. Asymptotic analysis of the
parabolic-channel flow reveals five temporal regimes, each with multiple spatial regions and a distinct spreading rate, reflecting the evolving spatiotemporal competition between injection and buoyancy. Initially, a thin film of gas spreads along the upper boundary; the channel slope and elongation of the film then generate a hydrostatic pressure gradient, which strengthens until buoyancy arrests the upper contact line and thickens the film. Beneath the film,
liquid then drains until the interface flattens under buoyancy. Analytical solutions of reduced-order models capture interface
evolution and contact-line motion through each regime and are validated against full numerical simulations. These results have implications for subsurface hydrogen and CO$_2$ storage, where a horizontal interface that advances vertically enhances both safety and storage efficiency.
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All authors Peter Castellucci, Radha Boya, Lin Ma, Igor L. Chernyavsky, Oliver E. Jensen
Fluid Dynamics
Maneuvering of an underwater vehicle using bio-inspired pectoral fins
Pedro C. Ormonde, Xiaowei He and Kenneth Breuer
A Cyber-physical
underwater vehicle is equipped with bio-inspired flapping fins positioned on the sides of the vehicle's main body. The proposed control surfaces are inspired by fish pectoral fins, generating forces and moments that can potentially be harnessed for maneuvering, hovering and station keeping. The streamwise and cross-stream forces produced by the fins are characterized for a range of reduced frequencies and Strouhal numbers. The streamwise forces are shown to be predominantly a function of the fin's projected frontal area, while the lateral forces also depend on the Strouhal number. When operated simultaneously, different flapping synchronizations can be employed for specific goals; a symmetric motion suppresses the lateral forces, while an anti-symmetric motion decreases the peaks of the streamwise force produced. The Cyber-physical vehicle demonstrates how the pair of fins can successfully maneuver the vehicle in the lateral direction.
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Physics and Society
Stochastic Networked Governance: Bridging Econophysics and Institutional Dynamics in a Positive-Sum Agent-Based Model
Alok Yadav and Saroj Yadav
Traditional macroeconomic growth models rely on general
equilibrium and continuous, frictionless institutional transitions, failing to account for the catastrophic structural collapses observed in empirical economic history. We propose the
Stochastic Networked Governance (SNG) model, a discrete-time,
agent-based framework that bridges econophysics, network science, and institutional economics. By defining jurisdictions through a binary institutional genome, the model formalizes institutional complementarity, endogenous growth, and the non-linear macroeconomic penalties of structural reform (the "J-Curve"). Using the CEPII
Gravity Database and the IMF Systemic Banking Crises
dataset, we move beyond theoretical
topologies to execute an empirical historical simulation from 1970 to 2017 across the top 100 global economies. Through Monte Carlo ensembles, we demonstrate how scale-invariant exogenous shocks and spatial capital flight drive global phase transitions, exposing the mathematical mechanics of the 1989-1991 Soviet collapse, the Hub-Risk Paradigm, and the emergent resilience of spatially firewalled
market networks.
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Chemical Physics · Cross-listed from cond-mat.stat-mech
Nudged Elastic Membranes for Constructing Reduced Two-Dimensional Potential Energy Surfaces
Uday Sankar Manoj, Nicole Drew, Ismaila Dabo et al. (+1 more)
Path optimization methods have been widely used and highly successful for the analysis of chemical reactions. Yet, they can fail to capture intrinsically multidimensional features of potential energy surfaces (PES). We introduce the nudged elastic membrane method, a framework for constructing two-dimensional reduced potential-energy surfaces in chemically relevant regions of a PES using only energies and forces without requiring more costly Hessian information. The method is demonstrated for a three-dimensional prototype model and for the triplet formaldehyde molecular system. In both cases, the resulting membrane captures one-dimensional reaction-path features as well as genuinely two-dimensional structures such as a yet unreported reported second-order saddle point in the PES of triplet formaldehyde. The method further provides direct access to structures that can serve as starting points for subsequent refinement. Our results show that the method offers a practical route to exploring multidimensional PES topography beyond the single-path picture.
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All authors Uday Sankar Manoj, Nicole Drew, Ismaila Dabo, Lukas Muechler
Physics Education
The Research Guide: From Informal Role to Profession
Sergey V. Samsonau and Matthew Pearce
Guiding others through authentic scientific research outside of PhD programs has been practiced for decades in specialized secondary schools, undergraduate research programs, and independent settings. These practitioners work in the middle, between the classroom science teacher and the PhD advisor, guiding learners with aptitude or serious interest. Sport and music have dedicated professions for this middle position (the school-team coach and the school band director); research does not. This paper names that missing profession the Research Guide: the practitioner who develops another person's capacity to do research, from framing a question to communicating findings. Hundreds of thousands of middle and high school students already pursue authentic research each year, even more college undergraduates participate in research with a faculty member, and millions of adults engage in citizen science. In current practice, the programs that serve this middle group mostly default to a simplified version of the PhD apprenticeship model structured around one mentor with a few students at a time, without systematic training; they overwhelmingly frame research as the hypothetico-deductive cycle alone. The role calls for cognitive apprenticeship, a pedagogical approach in which an expert's tacit moves on open-ended problems are made visible and scaffolded, then faded as the learner develops, while the research outcomes themselves remain unpredictable. It spans multiple modes of inquiry (not only the hypothetico-deductive cycle) and demands a combination that no existing training program produces: pedagogy, research methodology, developmental assessment, risk and productive struggle management, domain flexibility, and community building. Together these demands warrant a dedicated profession: a named role, a training pathway, a career ladder, hiring standards, and institutional recognition.
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Atomic Physics
High-order harmonic generation in argon driven by short laser pulses: effects of post-pulse propagation and windowing
Aaron T. Bondy and Klaus Bartschat
We present ab initio calculations using the $R$-
matrix with time dependence (RMT) method for high-order harmonic generation (HHG) in argon in a short, intense pulse regime. The calculations employ a $6$-cycle $\sin^2$ pulse at $850$ nm with peak intensity $2.3\times 10^{14}$ W/cm$^2$ and, for comparison with the experiment by Guo et al. [J. Phys. B: At. Mol. Opt. Phys. 51, 034006 (2018)], a Gaussian pulse with the same frequency and peak intensity. Both pulse shapes yield the expected harmonic structure in the region above the ionization threshold (approximately $15.82$ eV in $LS$-coupling). The spectra exhibit strong carrier-envelope-phase (CEP) sensitivity. The energy region leading up to the ionization threshold contains spectral features arising from residual coherent dipole oscillations (free-induction decay) that strongly depend on spectral windowing and the post-pulse propagation time. We show that the HHG spectrum, particularly below the ionization threshold, is a defined quantity that depends on analysis choices rather than being a uniquely determined observable. Comparison between theoretical predictions and experimental observations in this energy regime, therefore, requires explicit specification of these parameters.
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Atomic Physics · Cross-listed from quant-ph
The influence of evanescent waves on the nature of optical cooperative effects in atomic ensembles in a waveguide
A. S. Kuraptsev and I. M. Sokolov
Based on a consistent
quantum microscopic approach, we investigate the peculiarities of collective polyatomic effects in atomic ensembles placed in a waveguide, caused by the presence of evanescent modes of electromagnetic field. We analyze the influence of these modes on the process of cooperative spontaneous decay, as well as on the nature of radiation transfer in the ensembles under consideration. We show that under certain conditions, their influence can be dominant compared to the role of radiation modes, and the mechanism for this influence is the modification of dipole-dipole interatomic interaction.
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General Physics
Quantum Correlations in Classical Systems
Ghenadie N. Mardari
A classical fluid splitter produces the same patterns of energy redistribution as a Stern-Gerlach
quantum device, with rotationally invariant coefficients of correlation between molecular paths. Alternative settings express a cosine squared relationship, leading to Tsirelson-type Bell violations with outcome independence. This result confirms the Correspondence Principle of
quantum mechanics, where individual detection events express system-level properties according to Born's Rule. Kochen-Specker contextuality and Bell Locality are not formally contradicted, but their interpretation is in question. Current definitions of Local Realism are limited to intrinsic particle properties. In contrast,
quantum-like correlations require the acknowledgement of ensemble effects on dynamically inseparable entities, even when those entities are observed one at a time.
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Plasma Physics
Experimental observation of drift acoustic cnoidal waves in a magnetized plasma
Tanmay Karmakar, Rosh Roy, Lavkesh Lachhvani et al. (+5 more)
We report the experimental observation of highly nonlinear coherent structures in a linear magnettized
plasma characterized by a strong background density gradient and significant ExB velocity shear under high ion-neutral collisionality. These structures, identified as drift acoustic waves, exhibit large normalized density fluctuations reaching amplitudes of up to ~10% and show periodic sawtooth-like waveforms. These observed waveforms are well described by cnoidal functions, corresponding to stationary nonlinear wave trains. Cnoidal waves are exact solutions of the Korteweg-de Vries (KdV)-type equations, alongside the more commonly studied
soliton solutions. To the best of our knowledge, this work presents the first controlled experimental observation of cnoidal wave trains in a highly collisional magnetized
plasma through systematic variation of profile gradients. These findings provide important new insights into the nonlinear
evolution and saturation of drift acoustic waves in inhomogeneous, sheared, and collisional magnetized
plasmas.
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All authors Tanmay Karmakar, Rosh Roy, Lavkesh Lachhvani, Raju Daniel, Bhoomi Khodiyar, Prabal K. Chattopadhyay, Abhijit Sen, Sayak Bose
Optics
Program gain and loss for broadband soliton microcombs
Yuanlei Wang, Xinrui Luo, Binbin Nie et al. (+11 more)
Soliton microcombs provide compact, broadband, coherent light sources for precision metrology, spectroscopy, communications, and microwave photonics. Extending their spectral span while retaining useful output power remains challenging and often requires impractically high pump power. Existing approaches mainly tailor the dispersion and pumping conditions, but they do not exploit the coupling spectrum as a programmable aspect of
soliton operation. Here we introduce a meta-coupler whose lithographically programmed coupling spectrum concentrates strong pump access near the pumped resonance while leaving most comb lines close to the intrinsic loss rate. Si$_3$N$_4$ microresonators incorporating a meta-coupler exhibit broader circulating
soliton spectra, nearly twofold larger 3 dB
soliton bandwidths, up to about 12 dB higher central comb-line power, and up to about fivefold greater emitted comb power, without an additional pump-power penalty. Our work unlocks gain and loss as simultaneous programmable knobs for realizing high-performance
soliton microcombs.
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All authors Yuanlei Wang, Xinrui Luo, Binbin Nie, Du Qian, Zhenchao Mei, Yanwu Liu, Haoyang Luo, Junqi Wang, Yiwen Yang, Zu-Lei Wu, Tianxiang Hong, Bei-Bei Li, Qihuang Gong, Qi-Fan Yang
Chemical Physics
A Statistical-Mechanical Model for Dipolar Chain Formation
Zhongqi Liang and Jesús Peréz-Ríos
Dipolar fluids are known to exhibit complex self-assembly at low temperatures, yet a compact thermodynamic description of their aggregate statistics has remained elusive. Using molecular dynamics simulations of Stockmayer particles with a purely repulsive WCA core, we confirm that over broad regions of the ($\rho$, $T$) phase space the chain-size distribution follows an exponential decay with characteristic size $s_0$. Within this regime, we find that $s_0$ can be accurately described by an effective free energy $\phi$ that incorporates translational
entropy, bonding energy, and a crowding penalty. Identifying deviations from this ideal scaling provides a further division of the phase space into four regions. Therefore, our results locate a regime of relatively simple chain statistics and offer an alternative regime-based perspective on dipolar self-assembly.
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Atomic Physics
Error-correcting transition pulses for co-located spin ensembles without frequency selectivity
K. L. Wood and W. A. Terrano
We present a new class of control pulses designed to transfer co-located ensembles without relying on frequency selectivity, thereby allowing much faster state-transitions. A
geometric approach allows us to construct sequences which are robust to changes in the background
magnetic field along multiple axes, and errors in the pulse area. \red{These pulses are extremely fast, with robustness to pulse area shown at half the
quantum speed limit.} We demonstrate these sequences on
nuclear-dipole states, showing milliradian precision over several hours, 30-fold beyond the previous state of the art. This provides a path for extending the coherent integration time of ultra-long-lived
nuclear-
spin states to the fundamental limit set by their $>$10000 second lifetimes, as the limiting self-interactions of the
nuclei are suppressed in the symmetric superposition. The state-preparation quality demonstrated here directly opens up 30-fold improvements in next generation tests of the standard model, especially tests of the
symmetries of QCD and searches for dark matter; it is also crucial for the development of
nuclear-
spin based
quantum memories and may be useful in other scenarios demanding extremely fast but robust transitions.
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Atmospheric and Oceanic Physics
Geometric Correction of Side-Scan Sonar Images with Image-Consistent Attitude Refinement
Can Lei, Valerio Franchi, Hayat Rajani et al. (+3 more)
Side-scan sonar (SSS) images are susceptible to motion-induced
geometric distortion, which degrades their reliability for seabed interpretation and downstream tasks. Existing correction methods either exploit image-domain consistency without adequately preserving global
geometric referencing, or rely on
navigation-based geocoding whose effectiveness is limited when recorded attitude and motion fail to capture ping-scale perturbations. To address this issue, we propose a
geometric correction method for SSS images with image-consistent attitude refinement. The core idea is to refine the yaw-pitch sequence used in geocoding by explicitly linking stripe-wise distortion patterns in dual-sided waterfall images to
geometric deformation modes. Specifically, a
navigation-derived macro-scale attitude baseline is fused with image-inferred microscopic perturbations, where port-starboard
symmetry is used to separate pitch-related common-mode responses from yaw-related differential-mode responses. The refined attitude is then incorporated into a physically geocoding framework with track-aligned gridding and normalized-convolution-based hole completion to generate the corrected image. Experiments on real SSS
datasets from different sonar platforms and environments show that the proposed method reduces inter-ping misalignment, local stretching, and structural discontinuity, and improves local
geometric consistency under both degraded-attitude and cross-
dataset evaluation settings, demonstrating its effectiveness for geometrically consistent SSS correction.
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All authors Can Lei, Valerio Franchi, Hayat Rajani, Nuno Gracias, Rafael Garcia, Huigang Wang
Optics
Generalized Invisibility in Metasurfaces
Mustafa Yücel and Karim Achouri
Electromagnetic invisibility, defined as reflectionless transmission with zero phase delay, imposes strict constraints on metasurface designs that go beyond conventional reflection suppression based on the Kerker effect. This condition can be viewed as a metasurface analogue of radiationless states such as anapole excitations. Here, we show that invisibility in metasurfaces embedded in identical media can only be achieved by introducing degrees of freedom, such as non-zero angle of incidence or higher-order multipolar responses. We demonstrate that, in dissimilar substrate and superstrate, achieving invisibility within a dipolar framework fundamentally requires pure bianisotropic coupling, while purely electric and
magnetic responses are insufficient for lossless, passive and reciprocal systems. Using effective surface susceptibilities that account for the surrounding media and transverse wave vector, we derive closed-form conditions for both co- and cross-polarized invisibility. Importantly, we also demonstrate that the required bianisotropy does not need to be intrinsic, as an effective bianisotropic response may be achieved with anisotropic metasurface in dissimilar media leading to magnetoelectric coupling. Full-wave simulations of a metasurface at an air-dielectric interface confirm invisibility under oblique incidence. This work establishes a universal dipolar framework for invisible meta-optics in practically realistic scenarios.
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Applied Physics · Cross-listed from cond-mat.mtrl-sci
Organosilane-functionalized hydrothermal-derived coatings on titanium alloys for hydrophobization and corrosion protection
S. Rahimipour, B. Rafiei and E. Salahinejad
This work focuses on the structure, wettability and corrosion behaviors of Ti-6Al-4V
alloy after roughening treatments in different concentrations of NaOH aqueous solutions followed by low surface energy hexadecyltrimethoxysilane (HDTMS) coating. In this regard, scanning electron microscopy, contact angle measurements, potentiodynamic polarization and electrochemical impedance spectroscopy were used to characterize the samples. In contrast to hydrophilicity caused by the hydrothermal alkaline treatments, the subsequent HDTMS coating donated considerable hydrophobicity. Typically, the highest sessile water contact angle (about 147 deg) was obtained for the sample treated in 3 molar NaOH solution followed by the HDTMS coating. In addition, the alkaline treatment reduced the corrosion resistance of the surface in a NaCl aqueous solution; however, the HDTMS hydrophobization process improved it significantly. It is eventually concluded that the coupled use of alkaline treatment and HDTMS functionalization can be further considered for moisture-exposed applications of Ti-based
alloys.
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Atmospheric and Oceanic Physics · Cross-listed from econ.EM
From Clerks to Agentic-AI: How will Technology Change Labor Market in Finance?
Lu Yu and Xiang Li
Financial firms have gone through three major technological waves: computerization in the 1980s and 1990s, the rise of indexing and passive investing in the 2000s and 2010s, and the AI and automation wave from roughly 2015 to the present. This project studies how much labor is required to manage capital across those waves by tracking a simple productivity measure: assets under management per employee. Using a small panel of representative firms, we compare changes in AUM per employee, revenue per employee, and operating expense intensity over time. The goal is not to identify causal effects, but to document stylized facts about how technology changes the scale of asset management work.
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Physics and Society
Cycle holonomy captures higher-order compatibility constraints in remote synchronization
Lluís Torres-Hugas, Jordi Duch, Sergio Gómez et al. (+1 more)
Higher-order interactions have typically been modeled using hypergraphs or simplicial complexes, where interactions explicitly involve more than two nodes. Here we demonstrate that effective higher-order dynamical constraints emerge naturally on ordinary graphs, provided the interaction carries nontrivial topological structure. We study a gauge-coupled phase model with edge phase lags whose accumulation around closed loops produces gauge-invariant mismatches. We show that the associated twisted
Laplacian admits a zero mode if and only if all cycle holonomies vanish. Consequently, global compatibility is obstructed not by local pairwise mismatches, but by intrinsic topological frustration on cycles. We then connect this framework to the symmetric Sakaguchi–Kuramoto model, whose local coupling law differs from the gauge-coupled model but whose node phases impose cycle closure on physical phase differences. For cactus graphs, path mismatches induced by the symmetric lag can be represented through associated cycle holonomies, providing a static spectral encoding of their global residual incompatibility. Our results establish a spectral framework linking frustration to cycle-level constraints and identify cycle holonomy as a local-to-global diagnostic of path incompatibility in synchronization dynamics.
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All authors Lluís Torres-Hugas, Jordi Duch, Sergio Gómez, Alex Arenas
Physics and Society
Energy systems models are diagnostic tools, not projection machines
I. David Elder, Juan Moreno-Cruz, Cameron Wade et al. (+5 more)
Energy systems models (ESMs) are a leading tool to guide the energy transition. They have been influential in supporting national decarbonisation strategies and regional system planning, but these complex models can be opaque. Their results are often presented predictively or prescriptively, with little exploration of uncertainty and without clear discussion of limitations. Consequently, projections of ESMs have often been given more authority than their evidence can bear, undermining their contributions to energy transition policy. We argue that ESMs should instead be applied as explanatory, diagnostic tools. Model studies should explore uncertainty to find robust insights and define limitations, interrogate model behaviour to find testable real-world explanations, and communicate these explanations plainly and responsibly. This approach shifts the evidentiary burden from plausible projections to real-world insights that can be broadly understood and debated, and considered alongside other forms of evidence. Used this way, ESMs can support robust, justifiable, and pluralistic decision-making.
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All authors I. David Elder, Juan Moreno-Cruz, Cameron Wade, Sylvia Sleep, Sara Hastings-Simon, Sean McCoy, Heather L. MacLean, I. Daniel Posen
Optics · Cross-listed from quant-ph
Indistinguishablity from dephased emitters using combined plasmonic-dielectric cavities
Anastasios Fasoulakis, Ross C. Schofield, Rupert F. Oulton et al. (+1 more)
The concept of cavity funneling has emerged recently as a promising route towards creating indistinguishable
photons from highly dephased emitters. So far, all suggested solutions are solely based on dielectric cavities that require extremely high quality factors that are difficult to reach at visible wavelengths. Here we suggest a hybrid funneling architecture where a dephased emitter is coupled to a plasmonic nanoresonator that is enclosed by an outer dielectric cavity. The estimated lower limit of the outer cavity quality factor is found to be $\sim2$ orders of magnitude lower compared to a cascaded cavity system. Furthermore, the surrounding
topology of our approach allows for a partial direct coupling between the emitter and the outer cavity which in turn can increase the overall system extraction efficiency $\left(\beta\right)$ by a factor of 12, boosting the probability of
photon collection.
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All authors Anastasios Fasoulakis, Ross C. Schofield, Rupert F. Oulton, Alex S. Clark
Biological Physics · Cross-listed from q-bio.NC
Modelling time-order effects in haptic perception with a Bayesian dynamical framework
Gastón Avetta, Jose Lobera, Juan José Zárate et al. (+2 more)
Perceptual judgments of sequential stimuli are systematically biased by prior expectations and by the temporal structure of sensory input. In haptic discrimination tasks, these effects often manifest as time-order asymmetries, whereby the perceived difference between two stimuli depends on their presentation order. Here, we introduce a dynamical
Bayesian model that accounts for these biases by combining noisy sensory measurements with an evolving internal representation of stimulus intensity. The model formalizes perception as an inference process in which prior expectations are updated by incoming stimuli and propagate in time between observations. We test the model on psychophysical data from vibrotactile discrimination experiments, in which participants compare pairs of sequential stimuli with varying intensities. With a small number of parameters, the model quantitatively reproduces both the direction and magnitude of time-order effects across subjects, as well as the observed inter-individual variability. The inferred parameters provide a compact description of perceptual biases in terms of prior expectations and noise characteristics. Beyond fitting the data, the model induces a transformation of stimulus space, leading to a subject-dependent geometry of perceived stimuli. In this transformed space, perceptual judgments exhibit approximate
symmetries that are absent in the physical stimulus coordinates. These results suggest that temporal biases in perception can be understood as a consequence of dynamical inference, and that they impose non-trivial
geometric constraints on perceptual representations.
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All authors Gastón Avetta, Jose Lobera, Juan José Zárate, Inés Samengo, Damián G. Hernández
Computational Physics
Multiscale Assessment of Tritium Behavior in Preliminary Fusion Pilot Plant Design Using Surrogate Models in TMAP8
Lin Yang, Pierre-Clément A. Simon, Emre Yildirim et al. (+3 more)
The complexity and significance of multiscale phenomena in fusion energy systems make advanced modeling necessary for designing, optimizing, and safely deploying fusion plants. Tritium accountancy is one of those challenges for deuterium-tritium fusion systems. Its availability is constrained by its short half-life (12.33 years) and limited natural abundance, which require fusion plants to breed tritium onsite. Therefore, accurate tritium accountancy is essential for effective resource management, safety, and economics in fusion plants. Through the U.S. Department of Energy milestone program, Tokamak Energy Ltd. is developing a fusion pilot plant design and evaluating tritium retention and loss in key components and their effect on the fuel cycle. To rapidly explore design trade-offs and quantify design decisions on tritium management, this study presents a multiscale analysis to investigate tritium
diffusion, trapping, and recovery in key
plasma-facing components. To enhance computational efficiency, we integrate surrogate models at the component-level within a fuel cycle model at the system-level, enabling rapid evaluation of tritium recycling dynamics and inventory under various operational scenarios. The goal of this study is twofold: (1) demonstrate the feasibility of utilizing surrogate models to increase the accuracy of fuel cycle modeling, and (2) rapidly evaluate the performance of fusion technologies to accelerate design iterations. This multiscale model provides the tritium transport and retention behavior and supports the
plasma-facing components design optimization in normal and bake-out operations. The work is implemented using the Tritium Migration Analysis Program, Version 8 (TMAP8), an open-source application for tritium transport analysis in fusion systems.
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All authors Lin Yang, Pierre-Clément A. Simon, Emre Yildirim, José Trueba, Matthew Robinson, Masashi Shimada
Plasma Physics
Ion wake-mediated dust interactions under PK-4 conditions: a generalized and compact potential formulation
Diana Jimenez Marti, Benny Rodriguez Saenz, Peter Hartmann et al. (+3 more)
Dusty
plasmas, composed of electrons, ions, neutral particles, and charged
dust grains, exhibit self-organization phenomena such as string-like structures observed in microgravity experiments. The formation of these structures is influenced by ion wakes generated by streaming ions under external electric fields, as well as by time-evolving
plasma inhomogeneities such as ionization waves. Existing ion wake models, such as point charge and Gaussian-based representations, often rely on configuration-specific parameters, limiting their general applicability. In this work, we present a robust and general potential model for
dust and ion wake systems under PK-4-like conditions. Using a small set of coefficients determined from molecular dynamics simulations, the model captures the potential distributions for multiple interparticle distances. Its application to test cases and implementation in a small scale
dust dynamics simulation demonstrates its applicability to a wide range of
dust arrangements beyond string-like configurations.
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All authors Diana Jimenez Marti, Benny Rodriguez Saenz, Peter Hartmann, Evdokiya Kostadinova, Truell Hyde, Lorin Swint Matthews
Chemical Physics
Beyond the Virial Expansion: Microscopic Origins of Partial Molar Volumes in LiCl Solutions
Chun-Ting Lin, Diganta Dasgupta, Tinglu Yang et al. (+6 more)
Although electrolyte density measurements have been reported for over a century, employing them to obtain accurate partial molar volume (PMV) profiles as a function of salt concentration has remained elusive. Obtaining such curves requires precise density measurements combined with a proper treatment of the associated virial expansion. In this work, we obtain PMV profiles for aqueous LiCl solutions. The resulting data enable the development of highly accurate force fields for Li$^+$ and Cl$^-$ ions, revealing a clear progression from isolated ions to ion pairs and ultimately to higher-order chain and ring structures. Because ion clustering emerges from complex, nonlocal interactions, it cannot be easily mapped onto specific virial terms. Instead, a direct structural and volumetric interpretation can be achieved by partitioning molecular dynamic (MD) simulation snapshots into three-dimensional polyhedral regions associated with individual salt ions and water molecules. The corresponding ionic and water volumes from this treatment quantitatively reproduce the experimental PMV curve. The results demonstrate that the PMV for salt increases (while that of water decreases) up to 6.7 M. Above this concentration, the direction reverses as three- and four-body interactions become prominent. Complementary multivariate curve resolution (MCR) Raman spectroscopy and density functional theory (DFT) calculations elucidate the molecular-level details of water electrostriction, which also persists up to 6.7 M. Significantly, the PMV data can be correlated with key thermodynamic properties, including the osmotic coefficient and the eutectic point. The procedures established here provide a general framework for modeling electrolyte solutions and enable the development of a new generation of accurate force fields for aqueous ions.
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All authors Chun-Ting Lin, Diganta Dasgupta, Tinglu Yang, Cesare Malosso, Giulia Sormani, Colin Egan, Giovanni Bussi, Ali Hassanali, Paul S. Cremer
Optics
Cross Waveguide Design for Color-Centers in Diamond for Photonic Quantum Computing
Alessio Miranda, Ryoichi Ishihara and Salahuddin Nur
Color centers in diamond are a promising platform for
quantum computing applications because of their optical and
spin properties. However, diamond presents some technological challenges that limit its use in complex or large photonic
circuits. To mitigate these limitations, it is technically effective to separate the smallest possible diamond photonic structures or chiplet containing the color center(s) from the rest of the
circuit, which is fabricated on another material platform, and then heterogeneously integrate them. Considering efficient excitation and
photon collection from waveguide-coupled color centers, we design a cross waveguide as the primary component of our chiplet to access the color centers, channeling excitation and emitted
photons into different waveguides, and connecting the structure to the other components of the photonic
circuit. The chiplet containing the cross waveguide and supporting structures requires careful optimization of each subcomponent. The receptor's design is also critical for optimal signal transmission. In this paper, we develop a simple but efficient methodology to optimize the main components constituting both the chiplet and the receptor for their synergistic operation. The designed structure has an excitation-to-emission conversion of more than 5.4%, crosstalk of less than -40 dB, a working bandwidth of 160 nm, fabrication feasibility and tolerance within the limits of modern nanofabrication, and a mechanical solid structure with a footprint of less than 2000 $\mu$m
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Chemical Physics
Matthias Diez, Johannes K. Krondorfer, Albert Hirtenfelder et al. (+1 more)
Among the possible types of
magnetic dipole interactions in molecular systems, couplings between
nuclear motion and the
nuclear spin have probably received the least
attention in molecular spectroscopy. Although very small in comparison to effects related to electron
spin, this type of hyperfine interaction plays an important role in the NMR spectroscopy of molecular systems. While measurement and prediction of
spin-rotation tensors are a common place, vibrationally induced effects still lack a comprehensive description. In this article we develop a generic, theoretical framework that is well embedded in modern electronic structure theory and inspired by the Breit-Pauli
Hamiltonian for electronic interactions, distinguishing between
nuclear spin-orbit and
spin-other-orbit contributions. We show that the interaction of
nuclear spins with pseudorotational excitations of highly symmetric molecules may lead to experimentally accessible hyperfine splittings in NMR spectra, triggered by infrared light.
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All authors Matthias Diez, Johannes K. Krondorfer, Albert Hirtenfelder, Andreas W. Hauser
Biological Physics
Distinct Structural Dynamics of the Semiquinone State Define a Signalling Pathway in Avian Cryptochrome
Monika Kish, Suchitra Pradhan, Jessica L. Ramsay et al. (+3 more)
The light-dependent
magnetic compass of night-migratory songbirds is widely hypothesized to rely on the radical pair mechanism within retinal cryptochrome. However, bridging the mechanistic gap between microsecond
quantum spin dynamics and the long-lived, global
protein conformational changes required for cellular signalling remains a formidable challenge. Here, we apply redox state-resolved hydrogen/deuterium-exchange mass spectrometry (HDX-MS) to map the conformational landscape of European robin cryptochrome 4a (ErCry4a) across its photocycle. We reveal that photochemical reduction drives robust, allosteric structural transitions across key functional nodes, including the phosphate-binding loop (PBL), protrusion loop (PL), FAD-proximal helix {\alpha}17, and the C-terminal {\alpha}22/{\alpha}23 network. Crucially, we isolate the structural fingerprint of the transient semiquinone, the presumed signalling species. Rather than acting as a linear structural stepping-stone, the semiquinone exhibits a distinct, non-monotonic conformational signature characterized by a transient destabilization of the PBL and PL, contrasting sharply with the global rigidification observed in the fully reduced state. These findings establish the semiquinone as a structurally unique and functionally competent biological entity. Our results provide direct biophysical evidence for a dedicated, high-fidelity structural signalling cascade, detailing how localized
quantum-level photochemistry is translated into the precise conformational dynamics required for animal
navigation.
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All authors Monika Kish, Suchitra Pradhan, Jessica L. Ramsay, Paloma Munguía Salazar, Jonathan Phillips, Daniel R. Kattnig
Biological Physics · Cross-listed from q-bio.QM
Information-to-energy trade-offs and the optimal alphabet of polymer replication
Damián G. Hernández
We analyze information transmission in a recently proposed coarse-grained model of
polymer replication by framing it as a communication channel between templates and copies. By calculating the mutual information in the steady-state limit of long chains, we recover the accurate-random phase diagram and establish that the information per-monomer depends solely on template specificity within the accurate regime. Crucially, even in the accurate region, small error fractions lead to substantial information loss due to the nonlinear relationship between errors and mutual information. Examining the information-to-energy cost ratio reveals non-monotonic behavior as a function of monomer alphabet size, with an optimum determined primarily by the per-monomer assembly free energy. For DNA's four-base alphabet, we find that the observed effective assembly energy (at least $14\,k_B T$) places the system far from the information-transmission optimum, suggesting that biological replication may prioritize the suppression of spontaneous random assembly over information-to-energy efficiency. We also characterize achievable rate-fidelity trade-offs using Shannon bounds, providing a theoretical framework for evaluating future proofreading mechanisms in ensemble models.
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Geophysics
Efficient Generation and Quality Screening of Visible Windows for Regional SAR Reconnaissance
Linhong Li, Qi Feng, Kebo Li et al. (+1 more)
Regional synthetic aperture radar reconnaissance requires observation windows that satisfy
geometric feasibility under side-looking constraints and deliver interpretable image quality. This paper develops an efficient framework for visible window generation and per-window signal-level quality assessment. Window construction proceeds through three stages: coarse angular bandpass screening eliminates orbit arcs without potential target intersection, a planar characteristic curve containment test on the sensor calculation plane determines the precise geometry feasible intervals, and one-dimensional boundary bisection resolves each entry and exit epoch to subsecond precision. Each geometry feasible window then undergoes a companion point target stripmap simulation that measures range and azimuth impulse response width, peak sidelobe ratio, and integrated sidelobe ratio against mission-dependent acceptance thresholds. Numerical experiments validate the three-stage generation pipeline against an independent STK reference and demonstrate that the quality screening procedure differentiates imaging performance across observation windows with measurably different geometry. The framework provides an auditable preprocessing stage that converts continuous time regional visibility into quality-qualified observation windows suitable for subsequent mission planning.
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All authors Linhong Li, Qi Feng, Kebo Li, Yangang Liang
Classical Physics · Cross-listed from cond-mat.mes-hall
Nonequilibrium Kramers Turnover in a Kerr Parametric Oscillator
Daniel K. J. Boneß, Gabriel Margiani, Wolfgang Belzig et al. (+2 more)
Activation processes govern noise-induced switching between long-lived states. In an
equilibrium double well, the thermally activated switching rate exhibits a prefactor with a nonmonotonic dependence on environmental coupling, a foundational crossover known as Kramers turnover. Here, we demonstrate a Kramers turnover analogue in a Kerr parametric oscillator, a driven-dissipative nonlinear system featuring two stable phase states. First, we analytically establish turnover physics in this out-of-
equilibrium setting. There, the strong physical correlation between the activation barrier and intrinsic damping fundamentally obscures the underlying turnover physics. To overcome this limitation, we rescale the rotating-frame dynamics and introduce a tunable effective friction controlled entirely by the parametric drive. This rescaling comes at the cost of a concurrent rescaling of the effective temperature. Exploiting this simultaneous scaling, we leverage the effective temperature to extract the turnover directly from temperature-dependent observations. Subsequently, measuring noise-induced phase slips in a micro-electromechanical device, we observe a distinct crossover in the prefactor's temperature dependence. Our results unambiguously isolate the out-of-
equilibrium turnover regime and highlight that the competition between dissipation and fluctuations profoundly shapes activation dynamics also beyond
equilibrium.
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All authors Daniel K. J. Boneß, Gabriel Margiani, Wolfgang Belzig, Alexander Eichler, Oded Zilberberg