Fluid Dynamics
Direct numerical simulation of particle-laden flow in a linear compressor cascade: Unsteady boundary-layer effects on particle-blade interactions
Taiyang Wang and Yaomin Zhao
We perform point-particle direct numerical simulations (PP-DNS) of particle-laden flow through a linear compressor cascade subjected to synthetic free-stream
turbulence. Monodisperse particles are advanced in a one-way coupled Eulerian-Lagrangian framework with drag-only dynamics. We use PP-DNS collision statistics together with empirical deposition and erosion models to estimate particle deposition and blade erosion. Collision hotspots and regions of predicted deposition are identified near the leading edge and over the pressure side. On the pressure side, for the intermediate Stokes number, the onset of frequent collisions and predicted deposition is spatially associated with elevated boundary-layer intermittency during bypass transition. Nevertheless, for the largest particles, impacts occur farther upstream. On the suction side, sparse collisions and predicted deposition events appear only for the smallest particles and are phase-modulated by separation-induced
vortex shedding. Joint distributions of impact velocity and angle show that leading-edge impacts are faster and span wider angles than pressure-side impacts. For the two larger particle sizes, the higher normal impact velocities near the leading edge result in a greater likelihood of rebound than on the pressure side. Therefore, appreciable erosion is predicted primarily near the leading edge under the present conditions. The present results highlight the role of unsteady boundary-layer dynamics in affecting particle-blade interactions in compressor cascades.
Read the full abstract ▾
Fluid Dynamics
Lattice Boltzmann Methods with Anisotropic Equilibrium Distributions
Benjamin Kellers, Julius Weinmiller, Arnulf Latz et al. (+1 more)
Lattice Boltzmann methods are usually derived under the assumption of isotropy. In this work, we present a derivation of a
Lattice Boltzmann method for anisotropic fluid flow. Starting from an anisotropic
equilibrium distribution, we show a full derivation of the resulting
lattice Boltzmann method. We ensure that our method correctly reproduces macroscopic behavior via Chapman-Enskog analysis for a single-relaxation time collision operator. As a result, we are able to show that a properly discretized anisotropic Maxwell-Boltzmann
equilibrium does macroscopically in fact lead to an anisotropic variation of the Navier-Stokes equations. All desired properties of
lattice Boltzmann methods, such as locality of the collision operator, isotropic discrete position and velocity space, or mass and momentum conservation are retained. While it is explicitly shown in the context of fluid flow, the presented scheme is straight-forward to adopt to advection-
diffusion problems.
Read the full abstract ▾
All authors Benjamin Kellers, Julius Weinmiller, Arnulf Latz, Timo Danner
Fluid Dynamics
Acoustic radiation force on a liquid particle in a standing surface acoustic wave field
Shuo Huang, Hemin Pan, Daniel Ahmed et al. (+1 more)
We develop a theory for the acoustic radiation force on a
liquid particle in a 2D standing-wave field beyond the Rayleigh limit. The theory is valid for any frequency, includes the traveling-wave components due to the Rayleigh angle, and is thus applicable to a large class of surface acoustic wave applications. The analytical results are validated with respect to finite-element models. Using our analytical solution, we determine the parameter space for which Rayleigh-limit methods, such as the Gor'kov framework, remain applicable. This range is shown to depend on the particle properties, the Rayleigh angle, and even the particle position in the acoustic field. We propose a general form for the acoustophoretic contrast factor applicable to any wavelength of 1D standing-wave field, broadening the applicability of the classical Gor'kov framework. We show that the Rayleigh-angle effect can substantially weaken the acoustic radiation force, an effect that has been largely overlooked. We also confirm a frequency-dependent topological transition of the acoustic landscape that induces a switching of the field attractors and particle
equilibrium points. These results advance the quantitative theory of acoustic forces, unveil previously unresolved dynamical features of acoustofluidic fields, and provide a theoretical foundation for SAW-based
cell trapping, separation, and enrichment in acoustofluidics.
Read the full abstract ▾
All authors Shuo Huang, Hemin Pan, Daniel Ahmed, Thierry Baasch
Geophysics
Unveiling magma plumbing systems for volcanic eruptions and crustal accretion via active-seismic matrix imaging
Baptiste Hériard-Dubreuil, Milena Marjanović, Arnaud Burtin et al. (+1 more)
Submarine eruptions, accounting for over 80% of Earth's volcanic activity, primarily occur along mid-ocean ridges, where shallow magmatic systems are accessible to high-resolution imaging. Yet, their remoteness often leaves them undetected. Recent seismic studies at the East Pacific Rise (EPR) 9{\deg}50'N-one of the most dynamic ridge segments, imaged the detailed architecture of the shallowest magma lens, but no data-constrained model yet explains how magma accumulates, migrates, or triggers eruptions. Similarly, the formation of oceanic crust remains poorly understood. While 2-D seismic data reveal only a few vertically stacked, transient magma lenses, our study applies
matrix imaging, a novel technique in controlled-source seismology, to map the inner structure of on- and off-axis magma reservoirs. We uncover a conical on-axis reservoir and interconnected magma-rich zones throughout the crust. Combined with ophiolite evidence, these findings reveal that magma channels dominate the first 3 km for lower crust formation, while in situ crystallization prevails in the final 1 km, resolving a long-standing debate.
Read the full abstract ▾
All authors Baptiste Hériard-Dubreuil, Milena Marjanović, Arnaud Burtin, Alexandre Aubry
Fluid Dynamics
Asymmetric particle transport in turbulent flows within concentric annular ducts
Taiyang Wang, Chi Zhang and Yaomin Zhao
We present the first direct numerical simulations of particle-laden turbulent flow in concentric annuli to investigate the effects of transverse
curvature over a range of Stokes numbers. The results demonstrate that transverse
curvature induces asymmetric radial transport, with particles preferentially drifting toward the outer wall. Unlike canonical planar flows where turbophoresis universally drives near-wall accumulation, the present study identifies a distinct physical regime at the convex inner wall where centrifugal effect competes with turbophoresis. As a consequence, significant particle depletion is observed near the inner wall under strong
curvature, and the transient concentration field exhibits a non-monotonic
evolution, with the overshoot generally being more evident at higher Stokes numbers. By deriving a transport equation and applying Sturm-Liouville modal analysis, we identify the competition between asymmetric transport modes with different decay rates as the physical mechanism driving this non-monotonic
evolution, and establish a reduced-order model that captures the dynamics of the particle concentration near the walls.
Read the full abstract ▾
Atomic Physics
Experimental and theoretical studies of hyperfine structures in $^{21}$Na
Junho Won, Jeongsu Ha, Deuk Soon Ahn et al. (+38 more)
We measured the hyperfine structure constants, $A(3s^2S_{1/2})$ and $A(3p^2P_{1/2})$, of the
neutron-deficient isotope $^{21}\text{Na}$ using CLaSsy, a setup dedicated to collinear
laser spectroscopy at RAON. The hyperfine structure constants of $^{21}\text{Na}$ were measured to be $103.6(10)_{\mathrm{stat}}(9)_{\mathrm{syst}}$ MHz for $A(3p^2P_{1/2})$ and $954.9(11)_{\mathrm{stat}}(25)_{\mathrm{syst}}$ MHz for $A(3s^2S_{1/2})$. A systematic comparison with the state-of-the-art ab-initio relativistic coupled cluster calculations shows the role of higher-order correlation effects such as triple excitations in $^{21}$Na. Furthermore, the measurement demonstrates a capability of the CLaSsy setup to conduct collinear
laser spectroscopy experiments with a radioactive beam.
Read the full abstract ▾
All authors Junho Won, Jeongsu Ha, Deuk Soon Ahn, Sunghoon Ahn, Vivek Chavan, Anastasiia Chekhovska, Gyoungmo Gu, Kevin Insik Hahn, Seongjin Heo, Jangyong Huh, Dahee Kim, Do Gyun Kim, Dong Geon Kim, Jung Bog Kim, Sunji Kim, Yeong Seok Kim, Yung Hee Kim, Zeren Korkulu, Donghyeon Kwak, Jens Lassen, Jin Ho Lee, Jung Woo Lee, Chaeyeong Lim, Joochun Park, Ben Ohayon, Sung Jong Park, Xesus Pereira-Lopez, Peter Plattner, Sung Jae Pyeun, Liss V. Rodríguez, B. K. Sahoo, Taeksu Shin, Changwook Son, Yonghyun Son, Jaehyeon Song, Laszlo Stuhl, Kyoungho Tshoo, Hiroshi Watanabe, Yeong Heum Yeon, Hee Jung Yim, Hoon Yu
Atomic Physics · Cross-listed from cond-mat.mtrl-sci
Active learning of collinear magnetic Moment Tensor Potentials using the spin-MLIP package from soft-constrained spin-polarized DFT calculations: a case study of Fe-Pd
Arseniy Burov, Alexey S. Kotykhov, Dmitry A. Aksyonov et al. (+2 more)
Explicit incorporation of
magnetic degrees of freedom in machine-learning interatomic potentials (
magnetic MLIPs) plays a crucial role in the correct description of
magnetic materials and their properties. An important ingredient for fitting of
magnetic MLIPs is
spin-polarized density functional theory (DFT) calculations with non-
equilibrium magnetic moments, i.e. DFT calculations with constraints on
magnetic moments. In this study, we present a workflow for active learning of
magnetic Moment Tensor Potential (mMTP) during molecular dynamics (MD) simulations.
Magnetic MTP and its active learning
algorithm were implemented in the open-source
spin-MLIP code, DFT soft-constrained
spin-polarized calculations were performed with the VASP code, and MD simulations were conducted in the open-source LAMMPS code. We test our workflow on the Fe-Pd
crystal. The dependencies of magnetization and
phonon density of states (DOSs) on the volume of a supercell (or, pressure) are in good agreement with those calculated with DFT. Furthermore, the calculated DOSs correspond to the experimental ones.
Read the full abstract ▾
All authors Arseniy Burov, Alexey S. Kotykhov, Dmitry A. Aksyonov, Ivan S. Novikov, Vladimir V. Ladygin
Geophysics
The upper mantle of Europe and Western Asia: Exposing potentials and limits of regional full-waveform inversion
C. J. Schiller, S. D. Keating, S. Noe et al. (+7 more)
We present EUWA310, a seismic velocity model obtained by full seismic waveform inversion (FWI) model of the upper mantle beneath Europe and Western Asia. Inferred via 310 quasi-Newton updates from more than 260$\,$000 three-component seismograms at 18 s minimum period. It increases the number of iterations and the amount of data by an order of magnitude, compared to previous FWI studies in the region. The data include recordings from two dense regional arrays: IberArray on the Iberian Peninsula and in Northern Africa, and AlpArray in the wider Alpine region. The construction of EUWA310 became computationally tractable through the use of dynamic mini-batch optimization and the adoption of wavefield-adaptive spectral-element meshes from the global to regional scales. We also demonstrate that EUWA310 may be used to reduce uncertainties of moment tensor estimates by inverting waveforms with decreasing minimum period until an optimal minimum period of 22 s, below which no additional improvements is achieved. This limit is connected to the termination of the FWI at 18 s period, which did not result from limited computational resources, but from failure to explain data at even shorter periods. Since other continental-scale arrays – such as USArray or ChinaArray – are comparable in density and coverage, this observation suggests that we may have reached the regime where data coverage instead of compute power is the main bottleneck in regional FWI.
Read the full abstract ▾
All authors C. J. Schiller, S. D. Keating, S. Noe, S. Thrastarson, D.-P. van Herwaarden, C. Boehm, A. J. Rodgers, P. Barrera-Lopez, P. Marty, A. Fichtner
Atomic Physics
A High-Contrast Bragg Atom Interferometer for Testing Continuous Spontaneous Localization
Huaiyu Zhu, Ju Liu, Tao Zhang et al. (+3 more)
The continuous spontaneous localization (CSL) model is one of the most promising approaches to address the wave function collapse problem in the measurement process of standard
quantum mechanics. In this work, the effect of the CSL model on a Bragg atom interferometer was investigated. A Bragg interferometer achieving high fringe contrast of 99$\%$ has been demonstrated, maintaining this performance level at interrogation time up to $T=60~\mathrm{ms}$. The primary factors responsible for fringe contrast loss in the atom interferometer were systematically analyzed and corrected. This improvement established a new upper limit of $\lambda_{\rm CSL}=1.27\times10^{-5}~\mathrm{s}^{-1}$ at $r_C=10^{-5}~\mathrm{m}$ for the CSL collapse rate, representing approximately 4 times enhancement over previous atom-interferometric constraints.
Read the full abstract ▾
All authors Huaiyu Zhu, Ju Liu, Tao Zhang, Qin Luo, Zhongkun Hu, Minkang Zhou
Optics
Design principles for optoelectronic light-scattering reservoir computing at the edge of chaos
Geon Kim and YongKeun Park
Physical reservoir computing offers an energy-efficient route to sequential cognitive inference by outsourcing nonlinear temporal mixing to hardware substrates with rich intrinsic dynamics, with free-space light-scattering systems particularly attractive for their parallelism and reconfigurability-yet practical design principles linking hardware control variables to computational performance have remained unestablished. Here, we establish such principles by systematically mapping three physical control axes of a reconfigurable optoelectronic light-scattering reservoir-reservoir dynamics, input-reservoir coupling, and reservoir interconnectivity-and identifying a quantitative optimum along each axis. Within this design landscape, we observe a
memory-capacity peak that coincides with near-zero maximal Lyapunov exponent and is quantitatively reproduced in numerical simulation, extending edge-of-chaos confirmations previously reported in ion-gating and
spin-wave reservoirs into the photonic substrate. The two remaining axes exhibit a density-magnitude trade-off in input coupling and an intermediate optimum in reservoir interconnectivity. Operating at the resulting three-axis optimum, the reservoir achieves stable Mackey-Glass chaotic time-series prediction in free-running mode and 84.5% blind classification accuracy on the 10-class
Speech Commands spoken-digit
benchmark; the principles, stated in substrate-specific units yet rooted in substrate-independent concepts of criticality and balanced coupling, provide a transferable framework for reconfigurable optical reservoir hardware.
Read the full abstract ▾
Computational Physics · Cross-listed from cond-mat.mtrl-sci
Defect engineering of ultrathin gallium nitride via electric fields for advanced electronic, magnetic, and gas sensing applications
Yujia Tian, Devesh R. Kripalani, Ming Xue et al. (+1 more)
Scaling wide-band-gap
semiconductors to the ultrathin limit offers a transformative pathway for power electronics, with gallium nitride (GaN) representing a cornerstone material in this class. However, the operational resilience and functional tunability of its two-dimensional form (g-GaN) remain underexplored. This work shifts the focus from idealized systems to the complex materials behavior under realistic conditions, investigating how the synergistic effects of point vacancy defects, strain, and external electric fields govern its electronic,
magnetic, and sensing landscapes. We demonstrate that these factors are not merely perturbations but are fundamental to modulating the material response. Our first-principles calculations suggest g-GaN maintains electronic stability under intense electric fields; notably, gallium vacancies are predicted to further extend the theoretical stability limit. While in-plane tension preserves the band gap
evolution under an electric field, in-plane compression facilitates low-field metallization. Using nitrogen monoxide (NO) adsorption as a prototype, we find that the interaction is defect-modulated and potentially tunable by electric fields. Analysis of adsorption energetics and
diffusion barriers suggests the gallium vacancy may act as a thermodynamic trap for NO. Targeted hybrid-functional (HSE06) validation confirms the reliability of observed adsorption trends and theoretical metallization thresholds, while revealing that precise electronic-exchange treatment is critical for capturing the
magnetic ground state of nitrogen vacancies. By systematically examining the geometry, energetics, band structure, density of states,
magnetic response, and charge transfer, this study clarifies the interplay between defects and external electric fields, providing insights into theoretical upper bounds for property tuning and
semiconductor device engineering.
Read the full abstract ▾
All authors Yujia Tian, Devesh R. Kripalani, Ming Xue, Kun Zhou
Computational Physics · Cross-listed from cond-mat.str-el
Neural Autoregressive Control Variates for the Quantum Monte Carlo Sign Problem
Bei Qiao and Lei Wang
We train a pair of autoregressive models to construct zero-mean control variates to mitigate the sign problem in
quantum Monte Carlo simulations. The two autoregressive networks are confined to the positive- and negative-sign sectors with strictly disjoint support, and each is exactly normalized over its sector. Their difference is therefore structurally zero-mean, providing an unbiased auxiliary observable whose correlation with the sign
estimator controls the variance reduction. We implement the method within the
stochastic series expansion framework, which we extend to frustrated
lattices by developing an incremental loop-
topology update. Sign-ergodic sampling is achieved through a twist channel, which is the unique sign-changing mechanism on non-bipartite
lattices. We implement the control variates as autoregressive
transformers with an end-of-sequence parity mask that enforces exact sign-sector resolution, while the incremental loop-count change and cumulative frustration parity are incorporated as topological features. On the triangular-
lattice Heisenberg antiferromagnet, we
benchmark the method in the small-$N$ limit. The control variate reduces the standard error of the average sign by up to an order of magnitude and that of the energy
estimator by a factor of three to five, remaining effective even when the average sign drops below $10^{-3}$. This work lays out the framework and provides a proof-of-principle demonstration that autoregressive control variates can effectively mitigate the sign problem. Scaling to larger systems with physics-informed architectures is the subject of future work.
Read the full abstract ▾
Fluid Dynamics
Supervised machine learning of compressible flow past a rotating cylinder
Sanjeev Kumar, Santosh Kumar and Aditi Sengupta
High-fidelity numerical simulations of compressible flow past a rapidly rotating cylinder are used to investigate the
evolution of aerodynamic loads and flow instability over a wide range of Reynolds numbers (Re = 1000 to 6000). The study reveals a transition from periodic
vortex shedding to complex multi-mode oscillatory states, with a critical bifurcation identified near Re = 5650. Spectral analysis of lift and drag signals shows the emergence and interaction of multiple dominant frequencies, accompanied by amplitude modulation and nonlinear mode coupling in the post-bifurcation regime. To model these highly nonlinear dependencies, data-driven approaches are systematically explored using a database of 101 high-fidelity simulations (1 million core hours).
Polynomial regression provides baseline fits but fails to capture localized fluctuations near bifurcation.
Bayesian regression frameworks employing B-spline and Gaussian radial basis functions improve flexibility and uncertainty quantification, with spline-based models demonstrating superior performance in capturing piecewise nonlinear trends. Artificial neural networks (ANNs) are then developed as high-capacity surrogate models, achieving excellent predictive accuracy for maximum lift coefficient and instability onset time, while maintaining reasonable fidelity for the more challenging drag coefficient. Beyond regression, the ANN is further evaluated as a generative model to reconstruct flow behavior at unseen Re. A hierarchical refinement strategy is introduced, and results show that when trained on high-fidelity data, ANN-based models can serve as efficient and reliable surrogates for complex fluid dynamics problems.
Read the full abstract ▾
Space Physics · Cross-listed from cs.LG
Pretrained Approximators for Low-Thrust Trajectory Cost and Reachability
Zhong Zhang, Giacomo Acciarini, Dario Izzo et al. (+2 more)
Low-thrust trajectory design relies heavily on repeated evaluations of fuel consumption and transfer feasibility, which require expensive optimal control solutions. In this work, we show these quantities can be accurately approximated by machine learning surrogates, enabling fast and scalable evaluation across a wide range of scenarios. By increasing both
dataset size and model capacity, we observe that low-thrust trajectory optimization follows a scaling law, with performance improving linearly with the logarithm of training data and network parameters, and no evidence of saturation within the explored regime. Guided by this observation, we construct a large-scale
dataset using the proposed homotopy-ray strategy tailored to mission design requirements. A key is the introduction of a self-similar transformation, which allows generalization across semi-major axes, inclinations, and central bodies avoiding retraining. As a result, the same neural approximator can be applied to diverse orbital environments and mission classes. The proposed models accurately predict optimal fuel consumption and minimum transfer time for single- and multi-revolution transfers. Their performance and generalization are demonstrated on a public
dataset, a multi-asteroid flyby problem from the Global Trajectory Optimization Competition, and an asteroid rendezvous mission design. The models and
datasets are released as open-source to support the space community.
Read the full abstract ▾
All authors Zhong Zhang, Giacomo Acciarini, Dario Izzo, Hexi Baoyin, Francesco Topputo
Classical Physics · Cross-listed from math-ph
Laplace's law for sharp and diffuse interfaces
Sergey L. Gavrilyuk and Henri Gouin
We study both diffuse and sharp
liquid-vapor interfaces. The
equilibrium equation of fluids is derived by using the principle of virtual work in a domain including the interfaces. For diffuse interfaces, the surface tension coefficient depends on the density profile across the interface. For sharp interfaces, the
liquid-vapor layer is mathematically represented by a
geometric surface and its specific energy is a Dirac delta function at the surface. We compare the both approaches and find relations between the surface tension coefficient and parameters of the models.
Read the full abstract ▾
Plasma Physics
On Phase Transition of ITG Turbulence in the Dimits shift
L. N. Marquant, P. Morel and Ö. D. Gürcan
The transition between turbulent and zonal flow dominated states is investigated by varying the ion temperature gradient in nonlinear gyrokinetic simulations. Independent gradient scans reveal three distinct regimes: a turbulent regime at high gradients, a zonal flow dominated regime with strongly reduced heat transport at low gradients, and an intermediate regime characterized by intermittent switching between these two states. These different regimes can be classified using an order parameter, defined as the fraction of the zonal to total free energy in the system. To assess the
memory effects, the temperature gradient is first lowered gradually from high values that result in fully developed
turbulence, to lower values in the Dimits shift region that form strong zonal flows, and then is slowly increased back. Once the zonal flows form, and efficiently suppress
turbulence, they can persist at higher gradients, leading to an asymmetric response implying a hysteresis loop. It is observed that, in the zonal flow dominated state, the free energy is mostly condensated in the largest radial scale, with a steep slope of the $k_x$ spectrum, while in the turbulent state, it exhibits a wider spectrum with two distinct slopes.
Read the full abstract ▾
Biological Physics
Biophoton Emission from Palm during Meditation: A Multi-Method Complexity Analysis
E. Pace, L. De Paolis, G. Felici et al. (+5 more)
Biophotons are ultra-weak
photon emissions in the visible spectrum produced by living organisms. While extensively studied in plants, germinating seeds, and
cell cultures, no systematic multi-method complexity analysis of human ultraweak
photon emission (UPE) under physiological modulation has been reported. We address this gap by applying a comprehensive analytical framework to UPE measurements from the right palm of a human subject. Three independent sessions were conducted on different days, each comprising four consecutive 15-minute phases: Dark reference, pre-meditation resting state (Pre), structured meditation based on the Sama Vritti box-breathing protocol, and post-meditation recovery (Post).
Photon count series are analysed with four complementary methods: distributional statistics (Fano factor, skewness, tail Expected Shortfall); multiscale Fano factor and Allan deviation; stripe-filtered
Diffusion Entropy Analysis (DEA); and Renyi
entropy with a Time Reversal test. The methods show complementary sensitivities, converging on a coherent picture: a systematic reduction of emission intermittency during meditation, consistently detected across all three sessions. Stripe-filtered DEA places the emission in the non-ergodic renewal regime with a Pre-to-Meditation decrease of the scaling exponent. Renyi analysis reveals two effects: reduced marginal amplitude burstiness (Tdir) and increased sequential pattern structure (Tseq), interpreted as entrainment to the Sama Vritti rhythm. These findings are consistent with cardiac complexity transitions during meditation reported by Tuladhar et al. and with
EEG reorganization during Sama Vritti breathing by Zaccaro et al., suggesting a coordinated multi-channel physiological response. The results establish a proof-of-concept framework for complexity analysis of human UPE under physiological modulation.
Read the full abstract ▾
All authors E. Pace, L. De Paolis, G. Felici, I. Vaglini, M. Sandrini, M. Pettini, A. Gemignani, M. Benfatto
Fluid Dynamics
Sub-surface turbulence and free-surface features
Amélie Ferran, Ali Semati, Anaïs Rouaud et al. (+2 more)
Many turbulent flows encountered in nature – seas, oceans and rivers – are bounded by a deformable free surface. A question that remained to be fully explored is to what extent the underlying turbulent flow field can be revealed solely by observing the surface deformations. In this study, we attempt to correlate free-surface topological deformations with the underlying turbulent flow field. We report an experimental investigation of the free surface in the wake of a surface-piercing cylinder and
turbulence created by an active grid in an open-channel flow. We are able to study instantaneous events of surface indentations and their related sub-surface coherent structures, as well as statistical properties of velocity and surface motion. We observe weak cross-correlation between the vorticity field and the surface when considering the global surface elevation field. Slightly stronger correlations emerge when conditioning the surface on specific regions, even in the case of three-dimensional homogeneous isotropic
turbulence.
Read the full abstract ▾
All authors Amélie Ferran, Ali Semati, Anaïs Rouaud, R. Jason Hearst, Simen Å Ellingsen
Chemical Physics · Cross-listed from cond-mat.mtrl-sci
Visualizing Degradation in Anode-Free High-Utilization Aqueous Batteries Across Cell Lifetime
Sofia K. Catalina, Kyle Frohna, Willow Thompson et al. (+6 more)
Operando microscopy has unveiled key mechanistic insights in battery materials during early cycling, but long-term characterization to unveil material
evolution, degradation, and failure remain limited. To address this gap, we develop a custom operando optical microscope that captures images across hundreds of cycles and hours using optically accessible, anode-free pouch
cells. We image through-plane, bulk-representative electrodeposition behavior of aqueous tin metal anodes, which are promising due to their high energy density but whose reactivity limits practical cycle life. We show that substrate governs the morphology and stability of plated tin, particularly at high plated capacities. Specifically, copper substrates exhibit a multi-stage tin growth mode, which results in high overpotentials and irreversible active material loss at high plated capacities. In contrast, graphite substrates display a single-stage growth mode with slower kinetics. Using this insight, we balance performance and stability to demonstrate a high-utilization (70%, 630 mAh g$^{-1}_{Sn}$) porous graphite substrate Sn anode with high efficiency and long lifetime. Our results underscore the importance of material and device optimization guided by operando characterization across device lifetime with broad applicability to electrochemical systems.
Read the full abstract ▾
All authors Sofia K. Catalina, Kyle Frohna, Willow Thompson, Katherine J. Harmon, Dasol Yoon, Jianbo Wang, Colin Ophus, Daniel N. Congreve, William C. Chueh
Optics
Ultra-Low-Noise Brillouin Hybrid Synthetic Laser for Sub-Hertz Lattice Clock Spectroscopy
Meiting Song, Stefan Lannig, Dahyeon Lee et al. (+9 more)
Frequency-stable
lasers enable high-fidelity
quantum state manipulation, which forms the basis of optical atomic clocks,
quantum sensing, and
quantum computation. Performing state manipulations at increasingly high speeds requires
attention to
laser frequency noise at high
Fourier (carrier-offset) frequencies that cannot be addressed by traditional cavity stabilization alone. Scalable operations also benefit from device miniaturization. Here, we demonstrate a hybrid
laser stabilization approach that combines ultrahigh frequency stability of a cryogenic silicon cavity with high-
Fourier-frequency noise suppression of an integrated Brillouin
laser. The combined system suppresses frequency noise over a
Fourier span of more than 7 decades, yielding a <1 Hz phase-integrated linewidth and 0.2 Hz^2/Hz frequency noise at
Fourier frequencies above 10 MHz. The performance of this hybrid
laser is confirmed by sub-Hz Rabi spectroscopy with a three-dimensional ^{87}Sr
lattice clock. This work demonstrates record-low frequency noise at 698 nm over an extensive
Fourier frequency range and highlights the promise of precision clock spectroscopy using a chip-scale integrated
laser technology.
Read the full abstract ▾
All authors Meiting Song, Stefan Lannig, Dahyeon Lee, Lingfeng Yan, Andrei Isichenko, Nick Montifiore, Nitesh Chauhan, Max N. Frankel, Yu Hyun Lee, Shraddha Agrawal, Jun Ye, Daniel J. Blumenthal
Plasma Physics
Hydrodynamic Assessment of Direct Drive Inertial Confinement Fusion with Mixed $2\omega-3\omega$ Lasers
Guannan Zheng, Tao Tao, Qing Jia et al. (+3 more)
Ablation with mixed $2\omega$–$3\omega$
lasers is investigated as a possible drive strategy for balancing drive efficiency and ablative stabilization in direct-drive inertial confinement fusion. One-dimensional radiation-hydrodynamic simulations are performed for planar CH targets using the FLASH code [B. Fryxell et al, The Astrophysical Journal Supplement Series 131, 273 (2000)]. The total target-incident
laser intensity is varied from 100 to $1600~\mathrm{TW}/\mathrm{cm}^{2}$, and the $3\omega$
laser intensity fraction is scanned from 0 to 100%. Thick-target simulations are used to determine quasi-steady ablation-pressure scalings, while thin-foil simulations are used to characterize the acceleration stage and to evaluate the linear ablative Rayleigh–Taylor instability (RTI) gain using a Takabe-type model. The simulations show that adding a $3\omega$ component to a $2\omega$-dominated drive increases the effective ablation pressure, enhances the ablation velocity, and reduces the maximum linear RTI gain. Within the present one-dimensional hydrodynamic model, the mixed drive also reduces the target-incident energy required to accelerate the foil to $300~\mathrm{km}/\mathrm{s}$, especially at high intensity. This improvement is attributed to the deeper penetration of $3\omega$ light, which deposits energy closer to the dense ablation region and enhances conductive heat transport toward the ablation front. These results suggest that mixed-wavelength drive can recover much of the favorable hydrodynamic performance of $3\omega$ irradiation while retaining part of the energy-accessibility advantage of $2\omega$ operation, providing an additional design space of freedom for direct-drive target optimization.
Read the full abstract ▾
All authors Guannan Zheng, Tao Tao, Qing Jia, Jun Li, Rui Yan, Jian Zheng
Fluid Dynamics
Vibroacoustic Underwater Noise from Fixed and Floating Offshore Wind Turbines
Raúl Sanz-Ramírez, Martín de Frutos, Guillén Campaña-Alonso et al. (+2 more)
Anthropogenic
underwater noise from offshore wind turbines is a growing environmental concern, particularly with the large-scale deployment of bottom-fixed and floating devices. This study presents a physics-based vibroacoustic framework to predict operational
underwater noise emissions from offshore wind turbines and compares monopile-supported and floating configurations for a 10 MW turbine. The methodology combines time-domain aero-hydro-servo-elastic simulations with a frequency-domain acoustic formulation based on equivalent dipole sources and Green's function solutions, accounting for
underwater confinement between the free surface and seabed through the method of images. Results show that floating configurations exhibit enhanced low-frequency acoustic emissions, producing up to 15% higher OASPL than the monopile structures under equivalent water depths for frequencies below 10 Hz due to additional rigid-body motions, while monopile structures radiate more efficiently at higher frequencies associated with drivetrain excitations. Significant differences in the spatial distribution and directivity of the radiated sound field are also observed, with floating platforms displaying more complex three-dimensional radiation patterns and stronger direction-dependent variations, reaching approximately 20-25 dB in the 100-1000 Hz band, compared with the smoother and nearly axisymmetric response of monopile configurations. Water depth strongly influences propagation regimes and overall sound levels, with shallow-water floating configurations showing variations of up to 7% in OASPL relative to deep-water cases. The proposed framework enables quantification of vibro-acoustic noise and provides a predictive tool for assessing
underwater acoustic impacts during the design phase, supporting environmentally informed offshore wind turbine design and future regulatory and monitoring strategies.
Read the full abstract ▾
All authors Raúl Sanz-Ramírez, Martín de Frutos, Guillén Campaña-Alonso, Beatriz Méndez-López, Esteban Ferrer
Optics
Curved spacetime-induced control of photonic modes via spatially dependent band structure
Jingxuan Zhang, Suting Ju and Li-Gang Wang
Conventionally, controlling photonic modes require complex artificial structures made of electromagnetic media such as photonic
crystal, metamaterial, and waveguide systems. Here, we report a new mechanism for mode control induced solely by curved spacetime, which give rise to a spatially dependent photonic band structure. In this framework, the photonic mode can naturally undergo conversion in the spatial domain. We select two canonical models from general relativity–the Rindler spacetime and the Einstein-Rosen bridge (ERB)–to demonstrate light propagation effects. In Rindler spacetime, a light beam transitions to a diffusive mode for positive acceleration and to a highly collimated propagating mode for negative acceleration. In the ERB, beam transmission is governed by the Schwarzschild radius, which determines the extend of the spatial bandgap. Furthermore, an intriguing tunneling effect is also illustrated. Finally, we propose several feasible experimental methods to verify our theoretical predictions. Our findings elucidate a distinctive formation mechanism of photonic band structure in curved spacetime, enabling precise spatial control of light and the design of photonic devices within a non-Euclidean geometrical framework.
Read the full abstract ▾
Fluid Dynamics
A total-Lagrangian vectorial lattice Boltzmann method for finite-strain hyperelastic dynamics
Jingsen Feng and Xu Chu
Inspired by the vectorial
lattice Boltzmann method for linear elastodynamics \citep{boolakee2025linear}, we construct a total-Lagrangian vectorial
lattice Boltzmann formulation for two-dimensional finite-strain hyperelastic dynamics. The governing equations are first written as a conservative first-order system for the material velocity and the full deformation gradient. This representation separates the kinematic part of the dynamics from the constitutive closure: the first Piola–Kirchhoff stress is evaluated locally from the current deformation gradient and enters the
lattice only through nonlinear flux moments. A D2Q4 stencil with six-component vector populations is then used to match the state and the two material-coordinate fluxes. The formulation includes a second-order population initialization, trapezoidally centered body forcing, displacement reconstruction by velocity quadrature, and half-way reconstructions for velocity Dirichlet and Neumann traction boundaries on grid-aligned domains. The resulting method preserves the local collide–stream structure of standard
lattice Boltzmann schemes while adapting the vectorial first-order strategy from linear elastodynamics to hyperelastic finite-strain dynamics.
Read the full abstract ▾
Atmospheric and Oceanic Physics
A Comparative Analysis of Clustering Algorithms for Characterizing Surface Ocean Variability in the Western Mediterranean
Victor Rodriguez-Mendez, Enrico Ser-Giacomi, Jose J. Ramasco et al. (+2 more)
Understanding regional dynamical structures in the sea is fundamental to characterize energy transfer and transport properties, with implications in physical and biogeochemical modeling and characterization. In this work, we study the potential of clustering techniques to identify regional patterns, persistent or recurrent configurations, out of daily snapshots of sea surface temperature and kinetic energy in a region of the western Mediterranean Sea. From the methodological perspective, we use different clustering techniques: K-means, Self-Organizing Maps and InfoMap to verify if the patterns found are coherent across methods. Our results show that K-means and Self-Organizing Maps consistently delineate four distinct clusters of sea surface temperature configurations, aligned with the seasons even after removing the annual cycle, which indicates the persistence of seasonal structures beyond a mean effect in the temperature field. The study of surface kinetic energy, characterized by higher spatial and temporal variability, reveals more complex circulation regimes. While K-means and Self-Organizing Maps provide a robust and convergent classification of the dominant large-scale energy patterns, InfoMap uncovers finer-scale features such as localized jets and eddies. InfoMap, in particular, provides a complementary perspective to the partition-based methods, validating subtle yet significant hydrodynamic structures and acting as an anomaly detector for extreme events.
Read the full abstract ▾
All authors Victor Rodriguez-Mendez, Enrico Ser-Giacomi, Jose J. Ramasco, Cristobal Lopez, Emilio Hernandez-Garcia
Optics
Extreme Energy Concentration of Band-Limited Superoscillatory Vortices for Efficient Optical Micromanipulation
Chengda Song, Jing He, Xi Xie et al. (+4 more)
The Abbe diffraction limit, tied to the fundamental spatial bandwidth constraint imposed by any physical aperture, remains the primary barrier to achieving ultimate far-field optical resolution and precise light-matter interactions. However, current efforts to engineer structured light fields beyond this limit often come at the cost of massive sacrifices in energy efficiency. In this work, we mathematically complete the family of non-zero azimuthal-order Circular Prolate Spheroidal Wave Functions (CPSWFs), introducing them as a complete class of band-limited superoscillatory optical
vortices carrying helical phase. Compared with classical Laguerre-Gaussian (LG) beams, we rigorously prove that these eigenmodes achieve the theoretical upper bound for extreme energy concentration under strict band-limited constraints. At the scale of light-matter interactions, this optimal concentration directly amplifies the intensity gradients and angular momentum densities that govern optical forces. This advantage translates directly into a 29.9% reduction in the trapping power threshold and a 2.3-fold increase in the subdiffraction orbital rotation speed of nanoparticles. Looking forward, this fundamental physical framework not only establishes strict mathematical boundaries for structured light fields but also serves as an absolute theoretical
benchmark for deep-learning inverse design, and next-generation extreme optical micro-manipulation systems.
Read the full abstract ▾
All authors Chengda Song, Jing He, Xi Xie, Qian Wang, Yijie Shen, Fangwen Sun, Guanghui Yuan
Chemical Physics
Analytic first-order non-adiabatic coupling matrix elements of spin-adapted open-shell time-dependent density functional theory
Xiaoli Wang, Xingwen Wang, Zikuan Wang et al. (+1 more)
While
spin-adapted time-dependent density functional theory (TDDFT) approaches significantly improve the excitation energies and gradients of open-shell molecules, the effect of
spin-adaptation on non-adiabatic coupling
matrix elements (NACMEs) remains unknown for
spin-conserving excitations. In this article, we report the derivation, implementation and
benchmark studies of the ground state-excited state and excited state-excited state NACMEs of our
spin-adapted TDDFT method, X-TDDFT; to our best knowledge, this represents the first implementation of the analytic NACMEs of a
spin-adapted TDDFT method. Similar to the X-TDDFT analytic gradients, X-TDDFT NACMEs can be easily implemented on top of an existing U-TDDFT NACME implementation taking into account the restricted open-shell Kohn-Sham (ROKS) reference and the implicit involvement of doubly excited determinants, with acceptable computational overhead.
Benchmark calculations reveal that X-TDDFT reduces the error of U-TDDFT NACMEs by 1/3-2/3 (referenced against high-level multireference NACMEs), which leads to large corrections of internal conversion rates (up to two orders of magnitude). In particular, for copper(II) porphyrin, X-TDDFT leads to qualitative revisions of the relative importance of the excited state relaxation pathways, as well as the substituent effects of the internal conversion (IC) rates, suggesting that the error of U-TDDFT NACMEs is not only large but also unsystematic. It is therefore expected that X-TDDFT NACMEs will prove useful in the photophysics/photochemistry studies of open-shell systems such as radicals and transition metal complexes.
Read the full abstract ▾
All authors Xiaoli Wang, Xingwen Wang, Zikuan Wang, Wenjian Liu
Computational Physics
Local Surrogates for Harmonic Vibrational Entropy in Multilattices
Tina Torabi, Jiale Linghu and Yangshuai Wang
Harmonic vibrational
entropy is a key finite-temperature contribution to defect thermodynamics, but direct evaluation by dense Hessian diagonalization scales cubically with atom count and is too costly for supercell convergence, migration-path sampling, and high-throughput defect studies. We develop local surrogate models for harmonic
entropy in multilattices, including
semiconductors, ordered
alloys, and multispecies
crystals with multi-atom bases and internal degrees of freedom. Unlike Bravais
lattices, multilattices contain internal-shift degrees of freedom and optical
phonon modes coupled to acoustic strain;
entropy models must therefore resolve sublattice and species labels. For finite-range or screened atomistic models, we prove sublattice-resolved locality and cutoff-error estimates that justify replacing the global
entropy calculation by a local,
symmetry-respecting regression problem with controlled truncation error. This turns vibrational
entropy from a global spectral calculation into a reusable local site model with linear evaluation cost at fixed cutoff. Numerical tests confirm the predicted locality behavior and show that sublattice/species-resolved surrogates achieve accurate regression, transfer across supercell sizes, and linear-scaling evaluation on Stillinger–Weber Si and CdTe
benchmarks. The resulting method enables repeated harmonic-
entropy evaluations in multispecies defect calculations while retaining explicit stability, truncation, and surrogate-error controls.
Read the full abstract ▾
Optics
Observation of the Inherent Chiral Smith-Purcell Effect via Symmetry Breaking
Juan-Feng Zhu, Fei Chen, Jun-Xuan Chen et al. (+9 more)
The Smith-Purcell effect arises when charged particles move near a periodic structure, emitting radiation. Conventional approaches for generating
chiral Smith-Purcell radiation rely on metasurface phase engineering or resonant mode interference, typically producing narrow-band, weakly
chiral emission. Here, we introduce a resonance-interference-free mechanism that leverages the properties of the charged particles themselves. Using a non-
chiral, non-resonant silicon grating, we demonstrate broadband, tunable Smith-Purcell radiation with high chirality, achieving a record-high degree of polarization of 0.87. This is enabled by converting the transverse
spin angular momentum of electron-induced evanescent waves into a longitudinal form, producing opposite chirality at different azimuthal angles. Beam twisting or displacement offers precise control over chirality, paving the way for compact
chiral light sources, advanced X-ray imaging, and integrated particle diagnostics platforms.
Read the full abstract ▾
All authors Juan-Feng Zhu, Fei Chen, Jun-Xuan Chen, Junkang Shan, Ayan Nussupbekov, Febiana Tjiptoharsono, Xuan Dong, Mu Wang, Cheng-Wei Qiu, Zhaogang Dong, Ruwen Peng, Lin Wu
Optics · Cross-listed from quant-ph
Integrated squeezed light sources for two-mode entanglement in thin-film lithium niobate
Philipp Lohmann, Renato R. Domeneguetti, Daniel Wendland et al. (+6 more)
Scalable generation of nonclassical light sources on an integrated platform is a key requirement for photonic
quantum information processing. In particular, realizing multiple indistinguishable squeezed light sources on a single chip is an essential step toward continuous-variable
quantum computing. Here, we demonstrate the fabrication of two indistinguishable and independently controllable optical parametric oscillators on a thin-film lithium niobate (TFLN) platform. The device design focuses on reproducibility, independent tunability, and compatibility with larger telecom-wavelength continuous-variable photonic
circuits. We observe up to 0.5 dB of directly measured squeezing below the shot-noise level from each source. By interfering the two modes on a beam splitter, we generate an EPR-type two-mode squeezed state and verify continuous-variable
entanglement through violation of the Duan-Simon inseparability criterion. This is the first demonstration of two independently tunable squeezed-light sources on a single TFLN chip and their use for generating continuous-variable
entanglement.
Read the full abstract ▾
All authors Philipp Lohmann, Renato R. Domeneguetti, Daniel Wendland, Alessandro Perino, Tobias Egebjerg, Liam McRae, Jonas S. Neergaard-Nielsen, Wolfram H.P. Pernice, Ulrik L. Andersen