Optics
Enhanced enantiomer discrimination with chiral surface plasmons
Sang Hyun Park, Phaedon Avouris, Jennifer A. Dionne et al. (+2 more)
Strong light-matter coupling in
chiral cavities has been proposed as an effective way to selectively interact with an enantiomer that shares the same handedness as the cavity's
chiral mode. We show that surface plasmons supported by a two-dimensional interface with both electric and
chiral conductivities discriminate enantiomers more efficiently than
chiral optical cavities. A
quantum-electrodynamic treatment is developed to incorporate the molecule's electric and
magnetic dipole moments. We show that the discrimination factor for a
chiral plasmon can exceed that of the best
chiral-mirror cavity by almost an order of magnitude due to stronger field confinement. In addition, surface plasmons couple to a dipole's projection onto an entire plane, whereas cavity (or free-space) modes couple only to a single polarization axis. This
geometric difference produces a $\sqrt{2}$ orientation-averaged boost in
chiral discrimination for
chiral surface platforms. A handedness-preserving reflector further amplifies the enhancement, opening a practical route towards
chiral sensing using twisted-layer platforms.
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All authors Sang Hyun Park, Phaedon Avouris, Jennifer A. Dionne, Joshua D. Caldwell, Tony Low
Optics
Demonstration of MIMO-DFS over 100km of unamplified SSMF Link using Active Laser Drift Stabilization and Optimized Probing Codes
Rajiv Boddeda, Christian Dorize, Pierre Brochard et al. (+3 more)
We estimate the
laser frequency noise impact on coherent sensing using Distributed Fiber Sensing model. By stabilizing the
laser in the estimated frequency zone, we demonstrate reduced noise floor over 100km using optimized probing codes
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All authors Rajiv Boddeda, Christian Dorize, Pierre Brochard, Haïk Mardoyan, Carina Castineiras, Jérémie Renaudier
Optics
High-Resolution Coherent DFS Over 20km Ultra-Low-Loss Anti-Resonant Hollow-Core Fiber with Live Traffic
Rajiv Boddeda, Arnaud Dupas, Haïk Mardoyan et al. (+10 more)
We demonstrate sub-meter resolution Coherent DFS and detect acoustic oscillations using a stabilized
laser on 20 km of anti-resonant HCF with <0.10 dB/km loss without impacting live traffic of 1.2 Tbps on the adjacent channel.
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All authors Rajiv Boddeda, Arnaud Dupas, Haïk Mardoyan, Christian Dorize, Fabien Boitier, Peng Li, Zhang Lei, Jie Luo, Pierre Brochard, Carina Castineiras, Jelena Pesic, Florian Pulka, Jérémie Renaudier
Physics and Society
Ratio of Quantiles Indicates Burstiness with Fewer False Negatives than the Conventional Burstiness Parameter
Joshua Z. Stadlan, Michelle Birkett and Jason H. Rife
Complexity researchers view burstiness–fluctuating levels of activity–as evidence of hidden interactions within the system generating the activity signal. Yet, current burstiness metrics miss evidence of burstiness in some moderately bursty distributions and under moderate sampling conditions. The canonical Burstiness Parameter (BP) compares distributions of timing statistics to the exponential distribution, representing the timing of independent random events, but it provides false negatives for some parameter ranges of power laws, with and without cut-offs. We introduce a metric that maintains BP's measurement approach but reduces false negatives: the Burstiness Tail-based Index (BTI). Based on ratios of differences in
quantiles, BTI correctly classifies bursty distributions over certain parameter ranges misclassified by BP. Additionally, we find BTI to be more robust than BP in the presence of limited sample sizes and short observation windows, using simulated samples drawn from distributions correctly classified by BP in their analytical form. As a case study, we revisit an analysis of human activity data and find that the choice of BTI over BP influences interpretations of the timescales of burstiness in the
dataset. Given these analytical, simulated, and empirical results, we argue for BTI's practical advantage over BP in assessing burstiness in real-world temporal signals for complexity research and time series modeling.
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Applied Physics · Cross-listed from cond-mat.mtrl-sci
Zr Concentration-Dependent Sub-Lattice Phase-Field Model of Hf1-xZrxO2: Analysis of Phase Composition and Polarization Switching
Tae Ryong Kim and Sumeet K. Gupta
We develop a sub-
lattice phase-field model of Hf1-xZrxO2 incorporating zirconium (Zr) concentration (x)-dependence. Our framework expands the time-dependent Ginzburg-Landau (TDGL) equation to the sub-
lattice level and incorporates x-dependent interaction parameters and gradient coefficients. Our experimentally calibrated model captures the
evolution of charge-voltage (Q-V) characteristics for x ranging from 0.5 to 1.0. The sub-
lattice formulation explains the thermodynamic preference and kinetic transition barriers of competing orthorhombic phase (o-phase) and tetragonal phase (t-phase), while the phase-field framework enables spatially resolved analysis of polarization (P) and electric-field (E-field) profiles, allowing multi-domain (MD) polarization and mixed-phase states to emerge naturally. Our model reproduces the experimentally observed ferroelectric (FE)-to-anti-ferroelectric (AFE) transition as x increases from 0.5 to 1.0. At low Zr concentration (x = 0.5-0.6), the o-phase dominates, yielding distinct FE behavior. At high concentration (x = 0.9-1.0), the t-phase is stabilized, leading to AFE transitions. A key finding of our work is the unique behavior at intermediate Zr concentrations (x = 0.7-0.8). Here, the o- and t-phase energies are comparable, making the system strongly influenced by local variations in the electric field (E-field), which arise from stray fields near the domain walls. This non-uniform field distribution results in a mixed-phase composition and spatially staggered polarization reversal, which manifests as a more gradual Q-V
evolution compared to other values of x. By linking energy landscapes to spatial field effects, the model provides insights into the FE-to-AFE crossover in Hf1-xZrxO2.
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Fluid Dynamics · Cross-listed from cond-mat.soft
Stress network dynamics influence on large particle segregation
Alexander J. Navarrete, Leonardo Gordillo and Tomás Trewhela
A plethora of natural and industrial shear-driven granular flows exhibit particle-size segregation. Its occurrence is commonly attributed to two primary mechanisms: kinetic sieving and squeeze expulsion. While kinetic sieving is relatively well understood, squeeze expulsion lacks a clear mechanical explanation and direct experimental evidence due to difficulties in measuring stresses in granular media. Here, we investigate force networks around a large intruder in a bidimensional granular shear
cell. We use transparent, birefringent disks to visualize stress chains via photoelasticity. Experiments were conducted with two different granular media to study force chains over size ratios between the intruder and surrounding particles of 1.25 to 4.0. Particle Tracking Velocimetry and G-square analysis are used to quantify particle trajectories and identify active grains. These methods enable us to measure force-chain lengths and structures around the intruder through the gap factor. Our results confirm that squeeze-expulsion strongly depends on stress transmission. Larger size ratios lead to longer force chains and greater particle participation in the global stress network. In parallel, stress fluctuations predominate in driving or restraining intruder motion by forming anisotropic force chains. These findings advance the understanding of granular segregation by clarifying the link between force-network dynamics and segregation mechanics.
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Optics · Cross-listed from quant-ph
Quantum noise in ranging with optical pulses
Mylenne Manrique, Ilaria Gianani, Marco Barbieri et al. (+2 more)
Optical frequency combs combine ultrashort pulse duration and phase stability, making them powerful resources for high-precision ranging even when affected by atmospheric dispersion. It has been established that by classical modal engineering and mdoe-sensitive detection sensitivity to distance at the standard limit can be achieved, however attaining improved uncertainties by the use of squeezing has not been explored. Here, we apply an effective
Hamiltonian framework to the problem of ranging with
quantum frequency combs in order to derive the associated precision bounds for distance estimation. We analyse the role of intensity anti-squeezing and temporal beam shaping, and find that
quantum solutions may be appealing mostly for short-distance applications.
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All authors Mylenne Manrique, Ilaria Gianani, Marco Barbieri, Valentina Parigi, Nicolas Treps
Applied Physics
Temperature Dependent Characteristics of Quasi-vertical AlN Schottky Diodes on Bulk AlN Substrate
Md Abdul Hamid, Nabasindhu Das, Advait Gilankar et al. (+3 more)
We report on the fabrication and temperature-dependent characterization of MOCVD-grown quasi-vertical AlN Schottky barrier diodes (SBDs) on bulk AlN substrates. The SBDs exhibited high current densities exceeding 2 kA/cm2 at 10 V, with a turn-on voltage of ~3.0 V (at 1 A/cm^2) and an on/off ratio >10^9 at room temperature. Stable rectifying operation was maintained up to 300 C (the highest measured temperature), with a pronounced increase in current density at elevated temperatures due to thermally activated carrier transport, accompanied by an increase in extracted Schottky barrier height and a reduction in ideality factor. Capacitance voltage measurements showed strong temperature dependence due to the deep donor nature of Si in AlN, resulting in an increase in the net donor concentration (ND-NA) from ~5x10^17 cm-3 at 300 K to ~1x10^18 cm-3 at 373 K. Temperature-dependent reverse-bias characteristics were consistent with Poole-Frenkel emission as the dominant leakage mechanism, with an estimated trap energy of ~0.34 eV. Characterization using transmission electron microscopy and energy-dispersive X-ray spectroscopy revealed a ~5 nm AlNxOy interfacial layer at the metal/
semiconductor junction, which likely influences both forward and reverse transport. These results provide insight into carrier transport, leakage mechanisms, interface chemistry, and high-temperature characteristics, and guidance for the future development of high-performance AlN power devices.
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All authors Md Abdul Hamid, Nabasindhu Das, Advait Gilankar, Brad Lenzen, David J. Smith, Nidhin Kurian Kalarickal
Accelerator Physics · Cross-listed from quant-ph
Tennis-racket instability of twisted electrons
S.S. Baturin
We demonstrate that a weak nonlinear
magnetic entrance edge induces a tennis-racket (Dzhanibekov) instability in the shell-resolved orbital pseudospin dynamics of twisted electrons propagating in a nominally uniform solenoidal field. Starting from a Maxwell-consistent thin-edge extension of the entrance field, we derive an effective fixed-shell
Hamiltonian in which linear Schwinger pseudospin precession acquires an anisotropic quadratic correction. In the symmetric aligned limit, an exact linear eigenstate (a Laguerre-Gaussian
vortex state) becomes a
hyperbolic fixed point of the large-shell dynamics, producing recurrent reversals of the mean pseudospin projection. These reversals appear in real space as repeated conversions of the transverse profile between Laguerre-Gaussian
vortex and Hermite-Gaussian multi-lobed states. The unavoidable Lewis-Ermakov breathing of realistic wave packets does not generate a separate mechanism; it naturally modulates the nonlinear strength and sets the growth time scale. Microscope-scale estimates show that the required regime is accessible with standard octupole correctors in a transmission electron microscope.
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Fluid Dynamics · Cross-listed from cond-mat.mtrl-sci
Experimental measurements and modeling of characteristic time scales in single iron particle ignition
Liulin Cen, Yong Qian, XiaoCheng Mi et al. (+1 more)
Recyclable metal fuels such as iron are promising carbon-free energy carriers for heat and power. In such systems, particle ignition characteristics strongly affect combustion efficiency and combustor stability, making them critical for burner and reactor design. However, predictive ignition modelling remains limited by the lack of time-resolved data for single-particle solid-phase oxidation and phase transitions. In this work, digital in-line holography combined with ultra-high-speed single-color pyrometry is used to resolve characteristic solid-phase oxidation times of spherical micron-sized iron particles burning in well-defined hot oxidizing environments. Three temperature plateaus are identified, corresponding to FeO melting, the {\gamma}-Fe to {\delta}-Fe transition, and Fe melting, from which pre-melting oxidation times and melting durations are extracted. An ignition model based on solid-phase iron oxidation kinetics following a
parabolic rate law, coupled with external-oxygen-transport-limited description, is used to simulate these characteristic times. The model accurately captures the FeO-scale pre-melting oxidation time, which is nearly independent of oxygen concentration, while the FeO, {\gamma}-Fe to {\delta}-Fe, and Fe melting stages show strong oxygen-concentration dependence consistent with external-oxygen-transport-limited reaction rates. These measurements and simulations provide the first diameter-resolved
dataset for FeO and Fe melting processes and show that this modelling framework can quantitatively predict characteristic times for single iron particles in metal-fuel applications.
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All authors Liulin Cen, Yong Qian, XiaoCheng Mi, Xingcai Lu
Instrumentation and Detectors
Single-Photon Sensitive Optoelectronic Fibres for Distributed Nuclear Radiation Detection in Textile Fabrics
Nikhil Gupta, Hang Qi, Julian Kahlbow et al. (+4 more)
Nuclear radiation detectors play a key role in applications spanning
nuclear and particle physics,
nuclear engineering, security, and medicine. With the expanded global interest in
nuclear power, discreet, inconspicuous, and readily deployable
nuclear detection capabilities are increasingly important. However, conventional dosimeters are often rigid, bulky, or lack spatial resolution, limiting their use for mobile, conformal, or large-area distributed mapping of dynamic fields. Here, we present flexible, radiation-sensitive optoelectronic fibres with up to 50% elasticity for real-time gamma dosimetry. Silicon photomultipliers are thermally drawn into the core of fibres composed of a scintillator waveguide, enabling electronic-photonic integration and detection of scintillation light with single-
photon resolution. We show that these fibres are sensitive to localized
nuclear radiation exposure from collimated 0.5 {\mu}Ci Sr-90 {\beta}-sources and 10 {\mu}Ci Cs-137 and Co-60 {\gamma}-sources, with extended responsivity measured over 30 cm, and estimated lower detection limits approaching near- background radiation levels (~14-41 nSv/hr). Co-locating the scintillator and detectors in the fibre eliminates past length limitations driven by optical losses and enabling a greater collection cone through capture of transient non- guided modes. We further enhance radiation sensitivity and mechanical robustness by covering the fibres with a tungsten-merino wool composite braid, enabling us to machine-weave them into fabrics alongside common textile yarns. The tungsten wires function as a gamma-electron converter, increasing the detection efficiency of the assembly by ~20%. Distributed woven arrays of fibres formed in this way present an opportunity to create large-area, conformal fabrics capable of real- time dosimetry of gamma radiation fields with high spatial resolution.
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All authors Nikhil Gupta, Hang Qi, Julian Kahlbow, Igor Korover, Areg Danagoulian, Or Hen, Yoel Fink
Plasma Physics · Cross-listed from astro-ph.HE
Kinetic magnetohydrodynamics and Landau fluid closure in relativity
Abhishek Hegade K. R. and James M. Stone
Diffuse
accretion flows near a supermassive black hole are fundamentally weakly collisional. In such weakly collisional
plasmas, the ion and electron distribution functions can deviate significantly from thermal
equilibrium, and particle kinetic effects can influence large-scale fluid motion by driving pressure anisotropy, heat conduction, and
plasma instabilities. Modeling these
plasma effects in highly relativistic flows could be important for interpreting horizon-scale observations of black hole images. In this paper, we present a theoretical framework for understanding weakly collisional
plasmas in general relativity by deriving the relativistic drift kinetic equations from the Vlasov-Maxwell equations. We present the
evolution equations for the moments of the gyroaveraged distribution function and introduce a new analytic Landau fluid closure to capture anisotropic heat flow in relativistic
plasmas. Unlike standard (collisional) general relativistic magnetohydrodynamics or extended magnetohydrodynamics, our model does not rely on strong collisions to enforce thermal
equilibrium and consistently incorporates Landau damping in a fluid closure. The model introduced in this work provides a complementary approach to fully kinetic simulations in understanding weakly collisional effects in low-luminosity relativistic black hole
accretion disks.
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Plasma Physics
Ion Weibel Instability in the hybrid framework: the optimal resolution
Luca Orusa and Taiki Jikei
The study of collisionless shocks and their role in
cosmic-ray acceleration has gained increasing importance through both observations and simulations. Accurately modeling the shock transition region, where particle injection occurs, requires a proper description of the microinstabilities governing its structure. In high-Mach-number shocks, such as those associated with
supernova remnants, the ion Weibel instability is believed to provide the dominant dissipation mechanism. In this work, we investigate the ion Weibel instability driven by counterstreaming beams in the presence of an external perpendicular
magnetic field. We employ hybrid simulations, in which ions are treated kinetically while electrons are modeled as a charge-neutralizing fluid. Although hybrid models are widely employed to study collisionless shocks, the resolution requirements needed to accurately capture ion-scale instabilities remain poorly understood. We address this issue by developing a linear theory of the ion Weibel instability tailored to the massless electron assumption of hybrid models and validating it with one- and two-dimensional simulations over a wide range of Alfvénic Mach numbers. We show that hybrid simulations can reliably reproduce the growth, saturation, and polarization of Weibel-generated
magnetic fields in weakly magnetized regimes, provided that the relevant ion-scale modes are properly resolved. From the scaling of the dominant mode, we derive a minimum spatial resolution required as a function of Alfvénic Mach number. We also demonstrate that excessive resolution introduces unphysical small-scale whistler modes inherent to the massless-electron approximation. We validate the analysis by comparing the results with full particle-in-
cell simulations. Together, these results provide practical guidance for hybrid simulations of collisionless shocks and beam-driven
plasma systems.
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History and Philosophy of Physics
Causal Stance
Yoshiyuki Ohmura and Yasuo Kuniyoshi
What is the meaning of physical causal closure? Jaegwon Kim explicitly adopts a conception of causation according to which physical causation is effectively identified with deterministic physical lawfulness, and equates it with physical determinism. While this conception is internally coherent, it differs from currently dominant theories of causation. Physics and the theory of causation serve different descriptive purposes. In this study, we refer to them, respectively, as the Physical Stance and the Causal Stance. Within this framework, physical determinism belongs to the Physical Stance, and physical causal closure is defined only within the Causal Stance. Consequently, the two should not be equated. On this basis, this study reconstructs Davidson's anomalous monism as a materialist position that acknowledges mental causation without contradicting physical determinism. Furthermore, we propose a linguistic framework in which physical causal closure does not hold in the Causal Stance while physical determinism remains intact in the Physical Stance.
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Chemical Physics · Cross-listed from cond-mat.other
Weak Solutions to the Bloch Equations with Distant Dipolar Field
Louis-S. Bouchard
The distant dipolar field (DDF) is a long-range, nonlocal contribution to
liquid-state
spin dynamics that arises from intermolecular dipolar couplings and can generate multiple-
quantum coherences and novel MRI contrast. Its sign-changing kernel makes Bloch-DDF dynamics strongly geometry dependent, and FFT-based dipolar convolutions naturally assume periodic or padded Cartesian domains rather than bounded samples with reflective
diffusion boundaries. We study the Bloch equations with the DDF on bounded domains under homogeneous Neumann
diffusion conditions. We derive a finite-element weak formulation that supports spatially varying
diffusion and relaxation parameters and uses a short-distance regularization of the secular DDF kernel with length a>0. For fixed a we prove boundedness of the DDF operator, establish an L2 energy balance in which precession is neutral while
diffusion and transverse relaxation are dissipative, and obtain local well-posedness with continuous dependence on the data, with global existence under energy-neutral transport. For the Galerkin semi-discretization we show a discrete energy identity mirroring the continuum estimate. For computation, we evaluate the DDF in real space with a
matrix-free near/far scheme and advance in time using a second-order IMEX splitting method that treats
diffusion and relaxation implicitly and precession explicitly. The explicit stage applies a Rodrigues rotation at DDF quadrature points followed by an L2 projection, enabling stable multi-cycle lab-frame simulations. We validate against three closed-form
benchmarks and quantify curved-boundary effects by comparing mapped finite elements with a voxel-mask finite-difference baseline on spherical Neumann eigenmode decay. These results provide an analyzable and reproducible route for Bloch-DDF dynamics on bounded domains with complex geometry.
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Optics
Maximally localized modes of a multimode fiber
Nicolas Barré
This article presents an optimization method to find the most spatially concentrated basis of a multimode fiber, obtained by minimizing the sum of the spatial spreads of the individual modes over all
unitary transformations of a given orthonormal mode set. The resulting modes are the optical analogue of maximally localized Wannier functions in solid-state physics. We apply the method to the Laguerre-Gaussian basis of a graded-index fiber for mode counts ranging from 6 to 55. In all cases, the modes spontaneously organize into concentric rings without any
geometric constraint being imposed. The spot sizes and ellipticities evolve from one ring to the next in ways that
geometric packing approaches cannot predict. For large mode counts, the optimizer finds solutions where neither the number of spots per ring nor the spots within a given ring follow a regular pattern, indicating that the fully symmetric arrangement is no longer a minimum of the spread functional. A constrained variant of the method enables the optimizer to target any prescribed bundle geometry while quantifying its localization cost, opening a route to physically grounded photonic lantern design.
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Atmospheric and Oceanic Physics
Tracing the origin of tropical North Atlantic Sargassum blooms to West Africa
Francisco J. Beron-Vera, Maria J. Olascoaga, Phillipe Miron et al. (+1 more)
We simulate the dynamics of pelagic Sargassum rafts as systems of finite-size floating particles, governed by a Maxey–Riley law with nonlinear elastic interactions. Using surface ocean currents and wind data from reanalysis systems for clump transport, we computed trajectories within a domain covering the tropical and subtropical north Atlantic. The subsequent motion is reduced using Ulam's discretization method into a time-inhomogeneous Markov chain that simulates a background Sargassum concentration.
Bayesian inversion, combined with nonautonomous transition path theory, was used to infer the origin of the first significant recorded bloom in the tropical North Atlantic, which unfolded in April 2011. Both methodologies independently identified the bloom's origin as near the West African coast, up to two years before it was detectable via satellite imagery on the basin's western side. This finding supports anecdotal evidence of Sargassum strandings on the Ghanaian coast in 2009. Moreover, it correlates with unusual environmental conditions – such as increased nutrient loads from significant upwelling linked to a pronounced Dakar Niña and Saharan
dust deposition – that promote bloom proliferation. Additionally, it aligns with the observation that the species of Sargassum in the 2011 bloom differ from those in the Sargasso Sea, which might otherwise be considered a natural origin.
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All authors Francisco J. Beron-Vera, Maria J. Olascoaga, Phillipe Miron, Gage Bonner
Computational Physics
Proton Quantum Effects in H$_3$S Electronic Structure: A Multicomponent DFT study via Nuclear-Electronic Orbital Method
Jianhang Xu, Aaron M. Schankler and Yosuke Kanai
We investigate the impact of the
quantum effects of
protons on the electronic structure of high-pressure H$_3$S, a
benchmark hydrogen-rich
superconductor with a critical temperature ($T_c$) exceeding 200 K. Using
Nuclear-Electronic Orbital Density Functional Theory (NEO-DFT), we treat hydrogen
nuclei quantum mechanically on the same footing as electrons within a first-principles framework. Our calculations reveal that
nuclear quantum effects (NQEs) induce subtle modifications to the electronic band structure and density of states (DOS) near the
Fermi energy, including features associated with van Hove singularities. However, the resulting changes in the DOS would increase $T_c$ by only a few percent. On the other hand, calculations of the
phonon dispersion with the NEO-DFT method show large changes in the hydrogen-dominated
phonons that arise from a stiffening of the S-H bonds due to NQEs. These findings imply that the experimentally observed reduction in $T_c$ upon deuteration arises predominantly from changes in the
phonon properties, while NQEs-induced modifications to the electronic structure itself are minimal.
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Optics · Cross-listed from quant-ph
Modeling the non-Markovian Brownian motion of an optomechanical resonator
Aritra Ghosh, Malay Bandyopadhyay and M. Bhattacharya
We propose a representative, globally-admissible phenomenological spectral density of the bath for the non-Markovian Brownian motion of an optomechanical resonator, motivated by the near-resonance experimental observation of a non-Ohmic spectrum in [Nat. Commun. 6, 7606 (2015)]. To avoid divergences arising from a naive global extrapolation, we propose a globally-admissible, phenomenological bath spectrum that extends the experimentally-observed, near-resonance non-Ohmic behavior beyond the measurement window while ensuring finite bath-induced renormalizations and quadrature fluctuations of the resonator. The corresponding model of the structured environment produces a nonlocal mechanical response whose analytic pole structure encodes the observed linewidth. The resulting dissipation kernel exhibits a power-law-modulated exponential decay with transient negativity, signaling
memory effects. In the weak-coupling regime, the optical readout based on homodyne detection enables near-resonance spectroscopy and, with a calibrated drive on the resonator, permits, in principle, the reconstruction of the full mechanical susceptibility, thereby providing access to both the dissipative and dispersive bath contributions. Our results provide a consistent route from locally-inferred spectral properties to globally-admissible open-system descriptions and establish a framework for probing structured environments in cavity optomechanics.
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Computational Physics · Cross-listed from quant-ph
Hybrid Fourier Neural Operator for Surrogate Modeling of Laser Processing with a Quantum-Circuit Mixer
Mateusz Papierz, Asel Sagingalieva, Alix Benoit et al. (+3 more)
Data-driven surrogates can replace expensive multiphysics solvers for parametric PDEs, yet building compact, accurate neural operators for three-dimensional problems remains challenging: in
Fourier Neural Operators, dense mode-wise spectral channel mixing scales linearly with the number of retained
Fourier modes, inflating parameter counts and limiting real-time deployability. We introduce HQ-LP-FNO, a hybrid
quantum-classical FNO that replaces a configurable fraction of these dense spectral blocks with a compact, mode-shared variational
quantum circuit mixer whose parameter count is independent of the
Fourier mode budget. A parameter-matched classical bottleneck control is co-designed to provide a rigorous evaluation framework. Evaluated on three-dimensional surrogate modeling of high-energy
laser processing, coupling heat transfer, melt-pool convection, free-surface deformation, and phase change, HQ-LP-FNO reduces trainable parameters by 15.6% relative to a classical baseline while lowering phase-fraction mean absolute error by 26% and relative temperature MAE from 2.89% to 2.56%. A sweep over the
quantum-channel budget reveals that a moderate VQC allocation yields the best temperature metrics across all tested configurations, including the fully classical baseline, pointing toward an optimal classical-
quantum partitioning. The ablation confirms that mode-shared mixing, naturally implemented by the VQC through its compact
circuit structure, is the dominant contributor to these improvements. A noisy-simulator study under backend-calibrated noise from ibm-torino confirms numerical stability of the
quantum mixer across the tested shot range. These results demonstrate that VQC-based parameter-efficient spectral mixing can improve neural operator surrogates for complex multiphysics problems and establish a controlled evaluation protocol for hybrid
quantum operator learning in practice.
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All authors Mateusz Papierz, Asel Sagingalieva, Alix Benoit, Toni Ivas, Elia Iseli, Alexey Melnikov
Fluid Dynamics
Peristaltic pumping under poroelastic confinement
Avery Trevino, Roberto Zenit and Mauro Rodriguez Jr
Low Reynolds number flow near a poroelastic interface can be found across scales in biological and engineered systems. We develop a 2D model of peristaltic flow confined under a poroelastic solid. In this geometry, the lower boundary is an infinite train of traveling waves which pump fluid along a channel. The upper boundary of the flow is a poroelastic half space. The flow and deformation are solved analytically by an asymptotic expansion in the peristaltic amplitude and depend nonlinearly on dimensionless poroelastic stiffness, permeability, and interfacial slip. We quantify the effect of material properties on the poroelastic fluid-structure interaction. Peristaltic flow through the channel is inhibited by poroelastic confinement owing to increased viscous dissipation across the interface and energy loss in deforming the elastic solid. Permeability and slip interact with the material stiffness to produce material dependent regimes of forward or backward interstitial flow within the poroelastic domain. The maximum Darcy flow is found to occur at permeability values that optimize the elastic
matrix interaction.
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Applied Physics · Cross-listed from quant-ph
What quantum computer to buy?
Alex Krasnok
The phrase “buy a
quantum computer” hides several different procurement problems. An institution may be seeking cloud access for teaching, reserved capacity for research, a local instrument for hardware training, an optimization appliance, or a strategic installation that reshapes facilities, staffing, and budgets. Because these choices differ in purpose, operating burden, and useful lifetime, the decision should be framed as acquisition of
quantum capability rather than selection of a presumed hardware winner. This manuscript develops a practical procurement framework that distinguishes five capability layers, separates peer-reviewed results from commercial offerings, pricing anchors, and public roadmaps, and compares the main commercial platform families – superconducting
circuits, trapped ions, neutral atoms,
quantum annealing, and photonics – through the lens of institutional fit, access model, and refresh pressure. The main conclusion is that most institutions should begin with the smallest layer of capability that produces repeatable near-term value, builds internal expertise, and preserves strategic flexibility. Large on-premises systems are justified only when mission requirements, site readiness, staffing, governance, and upgrade paths are already clear.
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Plasma Physics
Hydrogen Inventory Simulations for PFCs (HISP)
Kaelyn Dunnell, Adria Lleal, Etienne Augustin Hodille et al. (+3 more)
Hydrogen Inventory Simulations for
Plasma facing components (HISP) is an open-source simulation tool to model the
evolution of hydrogen (H) isotopes inventory in
plasma-facing-components (PFCs) of
magnetic confinement fusion devices. The objective was to produce a demonstrative study describing the efficiency of tritium (T) removal strategies in ITER. HISP transforms
plasma code outputs to spatial-averaged inputs along ITER's first wall (FW) and divertor for 1D H transport models using FESTIM. Exposure conditions were tested in three scenarios that included DT operation and varied T removal methods. Generally, DT operation resulted in $\approx$ \SI{35}{g} of T in FW and divertor components after 10 days of DT pulses. Almost \SI{80}{%} of the total T inventory resided in co-deposited boron layers in the divertor. Baking proved to be the most effective T removal method in the divertor, decreasing T inventory by almost \SI{88}{%} for tungsten and almost \SI{30}{%} for boron. T removal was also evaluated from Glow Discharge Conditioning (GDC) - with a peak efficiency of \SI{23}{%} in the tungsten FW - and low power deuterium (DD) pulses - with a peak efficiency of \SI{13}{%} in the entire divertor. Due to the high removal efficiency of baking, inclusion of GDC and DD pulses in the tested scenarios did not meaningfully change final T inventory values, which varied by less than \SI{2}{%} in the FW and \SI{10}{%} in the divertor between scenarios.
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All authors Kaelyn Dunnell, Adria Lleal, Etienne Augustin Hodille, Jonathan Dufour, Remi Delaporte-Mathurin, Tom Wauters
Applied Physics · Cross-listed from cond-mat.mtrl-sci
Engineering 2D high-temperature ferromagnets with large in-plane anisotropy via alkali-metal decoration in a tetragonal CoSe monolayer
Yiran Peng, Yanfeng Ge, Yong Liu et al. (+1 more)
Two-dimensional (2D)
ferromagnetic materials with high Curie temperature ($T_{\rm c}$) and large
magnetic anisotropy energy (MAE) are critical for nanoscale spintronics but remain rare. We propose, via first-principles calculations, that adsorbing alkali atoms ($A$ = Li, Na, K, Rb, Cs) onto a tetragonal CoSe monolayer transforms it into a series of stable 2D
ferromagnetic metals, $A$CoSe, with an in-plane easy axis. Notably, LiCoSe is a half-metal. These functionalized monolayers exhibit dramatically enhanced ferromagnetism compared to the pristine layer, with $T_{\rm c}$ > 300 K and MAE > 800 $\mu$eV/Co. The coupled alkali atoms amplify the local
magnetic moment of Co ions, reinforce
ferromagnetic Ruderman-Kittel-Kasuya-Yosida (RKKY) and superexchange couplings, and concurrently weaken the direct
antiferromagnetic exchange between Co ions. Furthermore, tensile strain can further elevate the MAE (via band shifting) and increase $T_{c}$ (by strengthening the nearest-neighbor exchange $J_1$). Among them, NaCoSe exhibits the highest MAE and excellent strain-modulated $T_{c}$, rendering it the most promising candidate material. Our results establish alkali-metal decoration as an effective strategy for realizing 2D ferromagnets with high $T_{\rm c}$ and large MAE in tetragonal
lattices.
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All authors Yiran Peng, Yanfeng Ge, Yong Liu, Wenhui Wan
Optics
Phonon-phonon interaction as a control knob for multimode splitting in a two mirror parametrically assisted optomechanical cavity
Ghaisud Din
We study a driven optomechanical cavity with two movable mirrors and an intracavity optical parametric amplifier, focusing on how direct
phonon-
phonon coupling changes the observed normal-mode spectrum. Although the linearized system supports three hybrid modes, in the absence of direct mechanical coupling one collective mechanical mode contributes only weakly to the optical response, leading to an apparent two-peak structure. We show that finite
phonon-
phonon coupling mixes this weakly participating mode with the optically visible modes, making a third resonance clearly resolvable. This change appears in the mirror displacement spectrum, the output-field spectrum, and the output quadrature spectra, and becomes more pronounced with increasing coupling strength and drive power. Our results show that direct mechanical coupling provides a useful way to tune spectral visibility and multimode hybridization in two-mirror optomechanical cavity with intracavity parametric amplification.
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Applied Physics
A Novel Electrically Small Antenna Array Employing Opposite-Handed Chiral Parasitic Elements
Oleksandr Malyuskin
This paper presents a novel concept for electrically small
antenna arrays incorporating
chiral parasitic elements of opposite handedness. This configuration mitigates the detrimental effects of electromagnetic mutual coupling, which in conventional arrays causes a 180 degree phase shift between adjacent
antenna currents when the element spacing is less than half a wavelength. The proposed approach is experimentally validated using a seven-element monopole ESAA with compact dimensions, specifically below half-wavelength in cross-section and one-sixth to one-fourth of a wavelength in vertical range. The
antenna elements are spaced less than one-sixth wavelength apart, ensuring a highly compact footprint. Measurements show a minus 10 dB return loss, a fractional bandwidth of 5 to 15 per cent, and a realised gain of 5 to 9 dBi, along with full 360 degrees of azimuthal beam steering. The results confirm that employing oppositely handed
chiral parasitic elements can significantly enhance performance in densely packed, electrically small
antenna arrays.
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Optics
Reduced Optical Gain Threshold by Carrier Multiplication in Semiconductor Perovskite Nanocrystals
Zhen Zhang, Encheng Sun, Jian Li et al. (+4 more)
Carrier multiplication (CM) describes a strong charge-carrier interaction process in
semiconductor colloidal nanocrystals (NCs), wherein two band-edge
excitons are simultaneously created by an absorbed
photon with at least twice the bandgap energy (2 Eg). While being fundamentally intriguing, it has been exclusively utilized to enhance the light-to-electricity conversion efficiencies in the photodetector and
solar-
cell devices. In this report, we have synthesized the core/shell perovskite FAPbI3/NdF3 NCs with a biexciton recombination lifetime of ~3.9 ns, and demonstrated that a CM efficiency of ~25.7% can be achieved under the ~355 nm
laser excitation (~2.21 Eg). This CM occurrence leads to a two-fold reduction in the optical gain threshold, as compared to that obtained under the ~640 nm
laser excitation (~1.23 Eg). When combined with the single-
exciton and zero-threshold optical gain schemes previously developed for
semiconductor colloidal NCs, the CM effect introduced here would further mitigate the optical-pumping requirement for the routine operation of continuous-wave lasing.
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All authors Zhen Zhang, Encheng Sun, Jian Li, Chunfeng Zhang, Fengrui Hu, Min Xiao, Xiaoyong Wang
Physics and Society · Cross-listed from nucl-th
The Ground State Aspects and the Impact of Shell Structures on the Stability of Es-Isotopes
C. Dash, A. Anupam, I. Naik et al. (+2 more)
In this work, we have analyzed the
nuclear structure and several prospective decay characteristics of the $^{240-259}$Es$_{99}$ isotopes. For this we use Relativistic Mean Field model (RMF) with NL-SH and NL3* force parameter in an axially deformed oscillator basis. In structural properties, we have analyzed binding energy (B.E.), skin thickness ($r_{np}$) , charge radius ($r_c$), one
neutron separation energy ($S_{1n}$), two
neutron separation energy ($S_{2n}$), differential variation of two
neutron separation energy ($dS_{2n}$), the single particle energy and its variation with quadrupole deformation parameter of Es isotopes. We have also estimated the $\alpha$-decay, $\beta$-decay and cluster decay half lives of Es isotopes to analyze the shell structure and also to predict the suitable decay mode among them. The $\alpha$-decay half-life periods are calculated using the MUDL and AKRE formulae using both our calculated Q-values and empirically assessable Q-values. In a similar manner, we have computed the half-lives of cluster decay using Universal Decay Law and HOROI formula. A longer decay half-life indicates a shell stabilized parent
nucleus, while a small parent half-life suggests the shell stability of the daughter. This study provides us the insights regarding the structural changes with the change in
neutron number enabling us to predict shell closures and
nuclear stability. We found a shell/sub-shell closure at N = 154 for the NL-SH parameter set. This research aids in our comprehension of Es isotopes' shell structure and decay mechanism.
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All authors C. Dash, A. Anupam, I. Naik, B. K. Sharma, B. B. Sahu
Instrumentation and Detectors
Timing performance of large prototype based on $\upmu$RWELL- PICOSEC detector technology with $10 \times 10\ \mathrm{cm}^{2}$ active area
A. Pandey, K. Gnanvo, B. Kross et al. (+60 more)
The $\upmu$RWELL-PICOSEC detector, which combines a $\upmu$RWELL gaseous amplification structure with a Cherenkov radiator and photocathode, is a novel approach to acheive fast and precise timing in gaseous detectors. With timing precision at the level of tens of picoseconds, this technology is particularly suited for time-of-flight (TOF) applications in particle physics and potentially medical imaging. Beam tests with a 150~GeV/$c$
muon beam have been carried out on a large-area (10~$\times$~10~cm$^{2}$) prototype equipped with a cesium iodide (CsI) photocathode. Using an oscilloscope-based single-channel readout, timing measurements on two individual pads of the detector have yielded resolutions of $\approx$ 48 ps and $\approx$ 52 ps under different biasing conditions respectively.
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All authors A. Pandey, K. Gnanvo, B. Kross, J. McKisson, A. Weisenberger, W. Xi, J. Dutta, N. Shankman, L. Scharenberg, J. Alozy, Y. Angelis, S. Aune, R. Ballabriga, J. Bortfeldt, F. Brunbauer, M. Brunoldi, M. Campbell, R. De Oliveira, G. Fanourakis, J.M. Fernandez-Tenllado, K.J. Flöthner, D. Fiorina, M. Gallinaro, F. Garcia, I. Giomataris, S. Gomez, F.J. Iguaz, D. Janssens, A. Kallitsopoulou, M. Kovacic, P. Legou, M. Lisowska, J. Liu, M. Lupberger, R. Manera, I. Maniatis, A. Mariscal, J. Mauricio, Y. Meng, H. Muller, E. Oliveri, G. Orlandini, T. Papaevangelou, E. Picatoste, M. Piller, M. Pomorski, L. Ropelewski, D. Sampsonidis, A. Sanuy, T. Schneider, E. Scorsone, L. Sohl, M. van Stenis, Y. Tsipolitis, S.E. Tzamarias, A. Utrobicic, I. Vai, R. Veenhof, P. Vitulo, X. Wang, S. White, Z. Zhang, Y. Zhou
Applied Physics
Dynamics of a Spin-Wave Active Ring Resonator Driven by Harmonic-Null Square-Wave and Unipolar 8-bit Walsh Code Modulations
Anirban Mukhopadhyay, Kaustubh Narayan and Anil Prabhakar
Spin-wave active ring resonators (SWARRs) based on yttrium iron garnet (YIG) films exhibit rich nonlinear dynamics that make them promising platforms for physical reservoir computing. We present systematic and experimentally simple methods to characterize a SWARR's nonlinear behavior and
memory. We first use a third harmonic elimination method to probe the nonlinear response. A drive frequency $f_\mathrm{d}$ is modulated by a square-wave pattern engineered to have a spectral null at $3/T$, which is then applied as input to the SWARR. The power spectra at the output of the YIG delay line allow us to identify five distinct regions within a drive frequency range of $2.15 < f_\text{d} < 2.2\ \text{GHz}$ where nonlinearity was observed as frequency peaks at $f_\mathrm{d} \pm \frac{3}{T}$. The STM duration of the SWARR was estimated to be approximately 300 ns using a modulation pattern derived from the sequency-ordered 8-bit unipolar Walsh family. The nonlinear dynamics of the SWARR were further quantified by decomposing its temporal response to analog Walsh pulses in terms of the input Walsh codewords. The proposed methods of harmonic elimination and Walsh-function decomposition together provide a practical and general framework for the design and optimization of tunable
spin-wave reservoir computers.
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