Applied Physics
A model-inversion control strategy to attain desired equilibrium points when synthesizing nonlinear resonators
Maxime Morell, Emanuele De Bono, Emmanuel Gourdon et al. (+3 more)
The initial conditions of a deterministic nonlinear system affects the attained asymptotic solutions. This is a problem when the nonlinear behaviour is achieved by active control synthesis, and the initial conditions are not accessible for pre-constraining. Meanwhile, the generalized impedance control is recently gaining increasing
attention in acoustics, and has been enlarged to achieve nonlinear mechanical responses of Electroacoustic Resonators at low excitation levels. Nevertheless, as the initial conditions of Electroacoustic Resonators are hardly accessible, the
equilibrium points actually showcased by the synthetic nonlinear dynamics are not advantageous for noise attenuation in cavities excited by realistic noise sources. In this paper, we propose a control strategy being able to attain the desired
equilibrium points, due to the definition of an exosystem characterized by a desired nonlinear impedance and a synthetic external excitation. The exosystem dynamics is integrated in real time and its response is enforced in the actual system (in our case, the Electroacoustic Resonator), by a model-inversion feedforward strategy. The proposed
algorithm is implemented in the Electroacoustic Resonator, and is validated both numerically and experimentally. In particular, the experimental testing is conducted both in a quasi-open acoustic environment, and in enclosed cavities for acoustic mode attenuation.
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All authors Maxime Morell, Emanuele De Bono, Emmanuel Gourdon, Manuel Collet, Alireza Ture Savadkoohi, Claude-Henri Lamarque
Chemical Physics · Cross-listed from cond-mat.stat-mech
Time-delayed feedback turns Arrhenius escape logarithmic
Roy Podgaetsky, Vishwajeet Kumar, Arnab Pal et al. (+1 more)
Thermal escape is governed by the Arrhenius law, where the mean escape time scales exponentially with the barrier height. We show that the non-Markovianity induced by time-delayed feedback in the confining force removes this exponential scaling. Beyond a threshold set by the
curvature of the minimum, the delay destabilizes the well, and the thermal noise seeds an instability that is subsequently amplified deterministically to the boundary leading to slingshot escape trajectories. The escape time becomes logarithmic in the barrier, its fluctuations follow a Gumbel law, and an optimal delay enables escape faster than free
diffusion. Our results propose time delay as a tunable and experimentally feasible control parameter for accelerating activated processes.
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All authors Roy Podgaetsky, Vishwajeet Kumar, Arnab Pal, Ohad Shpielberg
Chemical Physics · Cross-listed from quant-ph
Efficient measurement schemes for the Monte Carlo projective quantum eigensolver
Divye Baid and Maria-Andreea Filip
The Monte Carlo Projective
Quantum Eigensolver (MC-PQE) was recently introduced as an alternative to hybrid
algorithms like the variational
quantum eigensolver (VQE). By using a
quantum Monte Carlo-inspired scheme for energy estimation, MC\nobreakdash-PQE was found to decrease the required measurement cost relative to comparable conventional approaches. However, in the context of VQE, numerous techniques have been developed to reduce the measurement overhead by joint measurement of multiple observables. In this work, we extend these approaches to the asymmetric expectation values required in MC-PQE and assess the performance of different techniques for various molecular systems of up to 12
qubits. We find full commuting Pauli term grouping combined with tailored measurement allocation techniques leads to a 5-10$\times$ reduction in standard error for the same total number of
quantum measurements. Conventional
Hamiltonian grouped measurement outperforms tractable classical shadows
tomography based techniques for the considered systems.
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Atmospheric and Oceanic Physics
Universal ordinary differential equations and the parameterization of warm-rain processes
Axel Seifert
The parameterization of warm-rain formation is a long-standing problem in cloud microphysics because the
evolution of bulk cloud variables cannot be derived uniquely from the kinetic collection equation (KCE). Universal ordinary differential equations (UODEs)provide a scientific machine learning framework that combines neural networks with ordinary differential equations and can learn dynamical operators directly from time series. Here, the UODE framework is applied to warm-rain formation by training on trajectories generated with a super-droplet model that approximates the KCE. In contrast to most previous machine-learning approaches, only the prognostic state variables are used for training, without requiring autoconversion or
accretion rates as targets. The learned closure accurately reproduces the KCE trajectories within the training domain and, although not explicitly constrained to do so, yields autoconversion and
accretion rates that closely resemble those diagnosed from the KCE. Analyzing the learned operator provides new insight into the structure of the widely used Seifert and Beheng (2001) warm-rain parameterization. In particular, it suggests that the empirical suppression of
accretion primarily compensates for an overestimation of autoconversion at small rain fractions. Motivated by these findings, a refined analytical formulation is proposed that improves agreement with the KCE while retaining the simplicity of the original parameterization. The results demonstrate that UODEs can serve not only as accurate surrogate models but also as a tool for understanding and improving analytical parameterizations of cloud microphysical processes.
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Fluid Dynamics · Cross-listed from cond-mat.mtrl-sci
Freezing of a deformable water-saturated porous medium. Part I: THM formulation, OpenGeoSys-6 implementation and benchmarking
Tymofiy Gerasimov, Christian B. Silbermann, Dmitri Naumov et al. (+3 more)
In this contribution, Part I, we present a coupled thermo-hydro-mechanical formulation for modeling and analyzing water-to-ice phase change in a deformable fully-saturated porous medium. It is implemented in the multi-physics computational platform OpenGeoSys-6. We compute a series of carefully designed
benchmark problems which critically examine the corresponding formulation components and the overall implementation. Several ingredients that have a qualitative and quantitative impact on the numerical results are identified, particularly dissected and commented on. Simulations also account for soil deformation induced by freezing (as a result of 9% volumetric expansion caused by water-to-ice phase transition). The forthcoming Part II will complete the code verification and validation campaign by considering a real full-scale three-dimensional case study of shallow subsurface ice storage. More specifically, we simulate the ice growth process in a fully saturated soil specimen surrounding a group of borehole heat exchangers (BHEs) that contain subzero temperature coolant fluid. A snapshot of the numerical results of this task is already depicted here in Part I as a teaser.
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All authors Tymofiy Gerasimov, Christian B. Silbermann, Dmitri Naumov, Olaf Kolditz, Haibing Shao, Thomas Nagel
Atmospheric and Oceanic Physics
Ice-thickness based scaling of wave attenuation in sea ice: Application and assessment of wave spectra
W. Erick Rogers, Jie Yu, Jean Rabault et al. (+2 more)
This study discusses recent advances in modeling waves in sea ice in the U.S. Navy's regional modeling system. It is applied in the marginal seas of the eastern Arctic Ocean, including the Barents Sea, Kara Sea, parts of the Greenland Sea, Norwegian Sea, and waters north of Svalbard. The focus is to assess the skills of two formulations of wave attenuation by sea ice used operationally in WAVEWATCH III. Both are derived from large field
datasets, one from the Arctic and the other from the Antarctic. The new model (IC4M9) describes wave attenuation depending on the ice thickness in association with the dependence on wave frequency, while the earlier default scheme (IC4M6) omits the dependence on ice thickness. The modeling results are evaluated against the satellite wave observations from SWIM/CFOSAT and the buoy measurements from the Svalbard Marginal Ice Zone 2024 Campaign (SvalMIZ-24). The comparisons with SWIM data validate the wave model skill in regions of open water or with light ice coverage. When evaluated against the SvalMIZ-24 data, the statistical performance of IC4M9 is substantially better than that of IC4M6, showing the influence of ice thickness on waves in the MIZ. Moreover, diagnosing systematic errors in the predictions by IC4M9, we find that the ice thickness field provided by the sea ice model CICE to the wave model is biased high in the MIZ, thus penalizing the performance of IC4M9 while not affecting the model IC4M6, which depends on frequency only.
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All authors W. Erick Rogers, Jie Yu, Jean Rabault, Ana Carrasco, Malte Müller
Computational Physics
OpenMUSTANC (MUltiple Scattering Theory At Nanoplasmonic Cavities): A MATLAB toolbox for the simulation of Plasmonic Sphere Aggregates
Xin Zheng, Christos Mystilidis, Christos Tserkezis et al. (+2 more)
Mesoscopic physical models, including the Hydrodynamic Drude Model (HDM), the Generalized Nonlocal Optical Response (GNOR) Model, and the Surface Response Model (SRM), have been proposed to investigate nonlocal effects in nanometric structures. The combination of classical electromagnetism with these mesoscopic material models calls for new computational electromagnetic (CEM)
algorithms, or update of conventional ones, in what is termed computational mesoscopic electromagnetics (CMEM). In this work, we present a MATLAB toolbox for the simulation of multiple spherical interfaces with arbitrary relative positions, with the incorporation of the aforementioned mesoscopic models. The method exploits vector spherical wave functions to properly express electric and
magnetic fields, an S
matrix formulation for the efficient treatment of incident and scattered fields at spherical interfaces, and a translation
matrix to deal with propagating waves with different expansion centers. Excitation sources can be chosen among arbitrarily polarized plane waves, dipoles and electron beams. For the post-processing part, the calculation of cross sections and far/near-field mapping; fluorescence enhancement, Purcell factor and
quantum yield; and cathodoluminescence and electron energy-loss probability is implemented. The toolbox is built in a modular manner, and each part (routine) has its own important functionality. This paper provides a full explanation of the proposed highly efficient and general toolbox, and a detailed guideline for researchers in the nanoplasmonics community.
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All authors Xin Zheng, Christos Mystilidis, Christos Tserkezis, Guy A. E. Vandenbosch, Xuezhi Zheng
Fluid Dynamics
Evolution of inertial particle clustering in decaying turbulence
Martín Obligado and Sofía Angriman
Inertial particle dynamics in
turbulence are commonly interpreted in terms of the instantaneous particle Stokes number, as supported by studies in statistically stationary homogeneous isotropic
turbulence. But in freely decaying
turbulence the Kolmogorov time scale evolves continuously, causing the effective Stokes number, St, to vary even though particle properties remain unchanged. Whether preferential concentration remains uniquely determined by this instantaneous St or depends on the flow's previous
evolution has remained largely unexplored. We investigate inertial-particle clustering during the decay of homogeneous isotropic
turbulence using direct numerical simulations of heavy point particles in the one-way coupling limit. Clustering is quantified through 3D Voronoï tessellations for populations evolving either from statistically stationary clustered states or initially random distributions. We consider both conventionally forced homogeneous isotropic
turbulence and velocity fields reconstructed using physics-informed neural networks. We show that preferential concentration cannot be described solely by the instantaneous St. While particle slip velocity follows the classical steady-state dependence on the instantaneous St, clustering statistics retain a measurable history dependence throughout decay. Existing stationary scaling laws remain applicable to cluster-size
evolution, but only through history-dependent prefactors. Particle distributions evolving from different initial conditions rapidly converge towards similar large-scale spatial organisation, indicating that the carrier flow determines the geometry of preferential concentration while finer clustering statistics preserve imprints of the previous
evolution. These results demonstrate that preferential concentration in non-stationary
turbulence is governed jointly by the instantaneous flow state and its initial state.
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Chemical Physics · Cross-listed from cond-mat.mtrl-sci
Chemically Resolved Topological Coordinates Link Structural Dynamics and Configurational Thermodynamics
Ayush Kumar Pandey and Abhishek Tewari
Atomic coordinates specify a structure, but they do not reveal how chemical connectivity across several length scales relates to atomic motion and configurational energy ordering. We formulate chemically directed persistent homology at four resolutions—complete networks, individual sites, spatial fields, and substitutional arrangements—while retaining the chemical identity and length scale of each connectivity feature. In ab initio molecular dynamics (AIMD) trajectories of $\delta$- and $\gamma$-CsPbI$_3$ at five temperatures spanning 500–700 K, the corner-sharing $\gamma$ network has a lower Pb–I restoring stiffness and permits larger iodide excursions, yet iodide positional correlations decay 2.27 times more slowly and Pb-network
topology retains
memory 1.63 times longer than in the edge-sharing $\delta$ phase. Local softness and loss of network
memory are therefore distinct. At individual sites, rare $\gamma$-phase Pb environments with a $\delta$-like Cs-cage connectivity precede 0.17 $\mathring{\mathrm{A}}$ greater Pb displacement over the subsequent 0.5 ps. The same Pb-network coordinate resolves disruption of corner-sharing connectivity across a 2560-atom $\delta|\gamma$ boundary. In substituted CsPbI$_3$, compact dopant arrangements undergo greater cooperative host relaxation and lie lower in density-functional-theory (DFT) energy than dispersed arrangements of the same composition. SchNet and Allegro model families with comparable energy errors encode opposite ordering along this coordinate, and 61 of 247 supplied models with errors below 1 meV atom$^{-1}$ on separate test structures reverse the DFT relation. Because relative configurational energies set Boltzmann populations, chemical network
topology links structure to physical response and tests whether learned energy models preserve DFT configurational ordering even when their average errors are small.
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Optics
Complex-gate all-optical frequency-resolved optical gating for ultrabroadband isolated attosecond pulse characterization
Minshuang Xia, Kaito Nishimiya, Dianhong Dong et al. (+2 more)
We experimentally demonstrate all-optical frequency-resolved optical gating (AO-FROG) for the characterization of ultrabroadband isolated attosecond pulses (IAPs) generated by a mid-infrared sub-cycle
laser field. By extending the AO-FROG framework beyond the conventional phase-only modulation approximation, we develop a strong-field approximation (SFA)-based theoretical framework and show that the weak perturbing field induces both phase and amplitude modulations during high-order harmonic generation. A complex-valued gate function is therefore required for accurate pulse reconstruction. Using a 2.26-$\mu$m sub-cycle driving
laser, we characterize IAPs spanning 100-180 eV in argon. The measured AO-FROG traces exhibit delay-dependent spectral modulations arising from perturbation-induced modifications of the electron trajectories and ionization probability. SFA simulations reproduce the experimental observations and confirm the importance of including ionization-induced amplitude modulation. The reconstructed temporal and spectral properties reveal an IAP duration of approximately 300 as and its spectral phase, providing access to the attosecond chirp of the generated pulses. Our results establish AO-FROG as a promising approach for temporal characterization of ultrabroadband attosecond sources driven by long-wavelength infrared fields.
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All authors Minshuang Xia, Kaito Nishimiya, Dianhong Dong, Yuxi Fu, Eiji J. Takahashi
Computational Physics · Cross-listed from cond-mat.mtrl-sci
Dark exciton signatures in the infrared transient absorption of MoS$_2$ monolayer
Tian-Xiang Qian, Marco D'Alessandro, Claudio Attaccalite et al. (+3 more)
Dark
excitons play a central role in the nonequilibrium dynamics of two-dimensional
semiconductors, but remain difficult to characterize. Transient-absorption experiments, with probes tuned in
exciton-
exciton transitions energy range (exc-tr-abs), can detect excitations from any populated dark
excitons, including
symmetry-forbidden,
spin-forbidden, and finite-momentum ones. In this work, we develop a $GW$+BSE scheme for computing exc-tr-abs spectra from arbitrary populated
exciton distributions. These dark
excitons are included equally by evaluating
exciton-
exciton dipoles in a locally smooth gauge, including intra- and inter-band contributions. For monolayer MoS$_2$, the exc-tr-abs signal arises from the $\Gamma$, $K$, $M$, and $Q$ valleys, differing substantially from the $\Gamma$-only interpretation.
Exciton-
exciton dipoles show similar intensities across these valleys, while their weights are dictated by initial excitonic populations. State- and
spin-resolved analyses assign the peaks to $1s \rightarrow 2p$ and $1s \rightarrow 3p$ transitions from both
spin-flip and
spin-conserving A and B
excitons across valleys and momenta.
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All authors Tian-Xiang Qian, Marco D'Alessandro, Claudio Attaccalite, Tian-Yi Cai, Sheng Ju, Davide Sangalli
Applied Physics · Cross-listed from cond-mat.soft
Polymer Membrane Tensegrity: Inverse Design of Polymer Films Morphing into Freeform 3D Surfaces with Digital Photopatterning Technique
Shuto Ito, Yuta Shimoda, Haruka Fukunishi et al. (+1 more)
In Metamorphosis of Plants (1790), Goethe traced diverse plant organs to transformations of a common leaf-like structure – a principle modern mechanics attributes to two material ingredients: non-uniform in-plane strain from differential growth or shrinkage, and spatially patterned stiffness. Here we translate this principle into a synthetic fabrication framework called
Polymer Membrane Tensegrity (PMT). A flat elastomeric film swollen with a second monomer is selectively UV-cured through a
liquid-
crystal display (LCD) photomask in a single-side digital photopatterning step, producing rigid rods embedded in a soft, shrinkable membrane. After the unreacted monomer is extracted with a solvent and the film is dried, the membrane shrinks far more than the rods, generating a ~50% in-plane strain differential and a ~2,000-fold modulus contrast – conditions under which the contracting membrane is held in tension by mutually unconnected rods, a tensegrity-inspired arrangement within a single film. An origami-based inverse design
algorithm computes the rod layout that morphs the film into a prescribed 3D surface. We demonstrate PMT on a dome, a
hyperbolic surface, and a gyroid unit
cell – positively and negatively curved targets – reproducing all three with mean deviations of 1.0-2.1% of the target size; perimeter curve optimization halves the mean deviation of the gyroid. Because patterning occurs on one side only, PMT eliminates the front-to-back
alignment demanded by
bilayer methods, offering a scalable route from flat
polymer films to freeform 3D surfaces.
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All authors Shuto Ito, Yuta Shimoda, Haruka Fukunishi, Mikihiro Hayashi
Instrumentation and Detectors
In-situ suppression of surface radon emanation using an HDPE barrier at the Stawell Underground Physics Laboratory (SUPL)
R.R. Marcelo Gregorio, K. Mintern-Lane, S. Rushbrook et al. (+5 more)
Radon-induced backgrounds remain a limiting factor in low-background experiments conducted in underground laboratories. The enclosed nature of these laboratories can result in elevated radon levels, with emanation from the surrounding rock representing the primary source of radon. In this work, we present an in-situ study of radon emanation from the floor of the main experimental
hall at the Stawell Underground Physics Laboratory (SUPL) and investigate the use of a high-density polyethylene (HDPE) barrier to suppress emanation. Surface emanation was measured using an AIRTHINGS Corentium Pro passive detector before and after installation of the barrier. The
equilibrium radon concentration within the surface emanation setup was reduced from 5840 $\pm$ 50 Bq m $^{-3}$ to 259 $\pm$ 3 Bq m$^{-3}$, corresponding to a suppression of $\sim$96%. These results demonstrate the potential to retrofit radon barriers to suppress surface emanation under realistic underground conditions, supporting their use in planned low-background infrastructure at SUPL and future applications at other underground laboratories.
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All authors R.R. Marcelo Gregorio, K. Mintern-Lane, S. Rushbrook, A.G. McLean, L.J. Bignell, J.M.C. Brown, G.J. Lane, N.J.C. Spooner
Optics · Cross-listed from eess.SP
Leveraging Bayesian Optimization for Array Shape Self-Calibration in Underwater DoA Estimation
Xin Gui, Tianang Li, Changjia Wang et al. (+3 more)
Flexible sensing arrays are commonly used in
underwater acoustic networks, but suppressed by unpredictable
geometric deformations. Existing array shape self-calibration methods often estimate individual element positions separately, leading to a high dimensional optimization problem over long arrays. To address this problem, this paper proposes a
Bayesian Optimization-assisted Geometry Estimation (BOGE) strategy operating with a hierarchical optimization process and a physics-informed parametric model for array geometry correction. BOGE formulates array shape self-calibration as an optimization problem, where candidate geometries are evaluated by the noise subspace residual. We perform
Bayesian optimization to configure the physics-informed parametric model and then refine the selected geometry through numerical optimization. Empirical results show that BOGE achieves lower mean
geometric root mean square error (RMSE) than the
benchmark methods across a wide range of noise levels. On the public SWellEx-96
dataset, BOGE achieves a
geometric RMSE of $0.659$ meters at $166$ Hz. A lake trial further shows that BOGE provides fixed source localization and moving target tracking performance comparable to the comparison methods.
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All authors Xin Gui, Tianang Li, Changjia Wang, Bowen Han, Yunchuan Zhang, Zhengying Li
Chemical Physics
Accelerated Quantum-Assisted Selected Configuration Interaction via Fast-Annealing-Based Determinant Selection
Hayun Park, Younghun Kwon and Hunpyo Lee
Full configuration interaction (FCI) provides exact electronic structure within a given atomic basis, but its computational cost grows exponentially with the number of
spin orbitals. Selected configuration interaction (SCI) methods alleviate this limitation by retaining only the most important Slater determinants. However, the repeated identification of important determinants remains a major computational bottleneck. We present a
quantum assisted selected configuration interaction (QASCI) method that combines SCI with graph based block diagonalization (GBBD) of FCI
Hamiltonian. The GBBD method partitions FCI
Hamiltonian into independent blocks, within which determinant selection problem is formulated as a quadratic unconstrained binary optimization (QUBO) problem. The QUBO problems for selecting determinants to construct SCI space are iteratively solved using a fast annealing approach. We
benchmark method on H8-H18 hydrogen chains and Li2S in STO3G basis. For Hn chains, chemical accuracy is achieved while retaining only a small fraction of Slater determinants, and this fraction decreases with increasing n, despite the exponential growth of the FCI
Hilbert space. For Li2S, QASCI results remain within chemical accuracy while retaining substantially fewer determinants than the full FCI space. We apply QASCI to N2 using the 631G basis, considering both active orbital and full orbital treatments. The full orbital QASCI calculation, using 50000 determinants, yields a lower ground state energy than an FCI calculation within an active space comprising 12
spin orbitals and 12 electrons. These results demonstrate that the combination of QASCI and the GBBD approach can substantially reduce computational cost of determinant selection while maintaining the accuracy of FCI based electronic structure calculations, thereby enabling accurate calculations in larger orbital spaces.
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Optics
Ghost infrared spectroscopy with bright twin beams
Akira Kawai, Makoto Shoshin, Kazuki Hashimoto et al. (+1 more)
Frequency-correlated light offers a route to mid-infrared (MIR) spectroscopy without direct spectral detection in the MIR. Previous MIR ghost spectroscopy has mainly relied on low-gain spontaneous parametric down-conversion (SPDC) and
photon-pair coincidence measurements, where the limited
photon flux has restricted acquisition times to longer than one minute. Here, we demonstrate ghost infrared spectroscopy using bright twin beams generated by high-gain parametric down-conversion (PDC). High-gain PDC amplifies
vacuum fluctuations, producing a different pair of frequency-correlated random spectra in each pump pulse. This pulse-resolved
stochastic emission is naturally matched to time-stretch detection, which records the spectrum of the correlated near-infrared telecom signal for every pulse, while the MIR idler is measured by bucket detection. Consequently, each pump pulse yields one paired projection measurement comprising a spectrally resolved reference and the corresponding bucket value. We reconstruct the transmission spectrum of a structured optical filter and the molecular vibrational absorption spectrum of
liquid benzene near 3.3 um with millisecond-scale acquisition, in good agreement with
Fourier-transform infrared spectroscopy. This reduces the acquisition time by four to five orders of magnitude compared with previous MIR ghost spectroscopy demonstrations. These results transform ghost spectroscopy from coincidence-based
photon counting to high-flux analog correlation spectroscopy, establishing a practical architecture for high-speed computational infrared spectroscopy driven by a narrowband
semiconductor laser.
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All authors Akira Kawai, Makoto Shoshin, Kazuki Hashimoto, Takuro Ideguchi
Accelerator Physics
Magnetizing nonlinear plasma wakefields for positron acceleration
Yung-Kun Liu, Pisin Chen, Ching-En Lin et al. (+2 more)
It is known that only a narrow
plasma wakefield sliver in the electron-beam-driven blowout regime suits positron acceleration. Using 3D simulations, we show that matching the cyclotron frequency $\omega_{c}$ with the
plasma frequency $\omega_{p}$ forms a stable electron column on axis, expanding the suitable phase space for positron acceleration sizably. For a
plasma density $n_p = 10^{16}\text{ cm}^{-3}$ in a 35 T field, the interval expands 4.3 times, and a witness positron beam gains 100–150 MeV over 6 cm ($1.6$–$2.5$~GeV/m) with a 92% capture rate.
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All authors Yung-Kun Liu, Pisin Chen, Ching-En Lin, Spencer Gessner, Bernhard Hidding
Fluid Dynamics
Drag reduction and subcritical turbulence in controlled pipe flows
Emanuele Gallorini, Daniele Massaro, Philipp Schlatter et al. (+1 more)
Pipe flow controlled by streamwise-travelling waves of azimuthal wall velocity is studied using direct numerical simulations at a bulk Reynolds number $Re_b=4900$. A comprehensive analysis of drag reduction shows that the flow response differs fundamentally from that of channel flow. Under suitable forcing, pipe flow relaminarizes, whereas channel flow does not. Depending on the control parameters, the flow exhibits the spatially localized turbulent state characteristic of transitional pipe flow, with turbulent puffs persisting at bulk Reynolds numbers up to three times higher than in the uncontrolled case. The bulk Reynolds number alone does not determine the onset of localization. Moreover, drag reduction, which alters the natural relation between bulk and friction velocities, is insufficient to identify a universal onset criterion. An intermittency indicator based on the spatial variance of the cross-sectional turbulent kinetic energy relates the emergence of localized
turbulence to the low wall friction produced by the control, although the correspondence is not one-to-one. Despite their qualitative resemblance to canonical turbulent puffs, the controlled puffs exhibit distinct properties; for example, their fronts may propagate faster than the bulk flow. Overall, this work provides a comprehensive characterization of the subcritical turbulent state and its turbulent puffs in controlled pipe flow, and offers a new perspective on control strategies that aim at flow relaminarization.
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All authors Emanuele Gallorini, Daniele Massaro, Philipp Schlatter, Maurizio Quadrio
Fluid Dynamics
A Physics-Informed, PIV-Based Method for Surface Pressure Reconstruction
Abbas Daliri and Fulvio Scarano
A physics-informed method for PIV-based surface pressure reconstruction that combines least-squares optimization with both local and global physical constraints is proposed. The standard deviation of the surface–normal pressure gradient is introduced as a physically meaningful weighting function in the optimization process. Moreover, a physical global constraint is also introduced to reconstruct surface pressure outside the suction region. The results show very good agreement with data obtained from pressure taps. Near the leading edge, the surface pressure reconstruction error has been reduced by one-third.
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Medical Physics
Imaging cellular-level brain microstructure with diffusion MRI
Xiaodong Li, Jing Zhao, Baolan Lu et al. (+4 more)
Noninvasive live-
cell imaging in deep human tissues is crucial for exploring the cellular biological and pathogenic processes, but remains a significant unmet challenge.
Diffusion magnetic resonance imaging (dMRI) promises to narrow this gap by noninvasively providing cellular-level microstructural information. Within a single crowded voxel containing millions of living
cells, the intricate cellular-level microstructures create numerous microcompartments, each characterized by a specific diffusivity. However, conventional dMRI methods relying on voxel-averaged macroscopic parameters, merely reflect aggregate microstructural properties and fail to quantify this distribution of microcompartment-specific diffusivity within a voxel, thereby obscuring microstructural details. Here, we propose an intravoxel diffusivity probability distribution (IDPD) model to resolve a wealth of essential microstructural information via quantifying microcompartment-specific diffusivity distribution, thereby enabling direct cellular-level characterization. This exceptional capability is realized through a multi-tiered analytical workflow spanning targeted single-voxel or region of interest (ROI) analysis to global visualization using dynamic
videos and statistic parametric maps. Ultimately, the IDPD model enables noninvasive cellular-level microstructure imaging, offering a promising avenue to evaluate living
cell functions in vivo.
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All authors Xiaodong Li, Jing Zhao, Baolan Lu, Jinzhu Wang, Xinhua Wei, Qingxian Yang, Xuegang Xin
Classical Physics · Cross-listed from astro-ph.EP
Planar Three-Body Problem: theoretical predictions and simulation results
Yogesh Dandekar, Ethan Springer, Shoval Zard et al. (+3 more)
We investigate the statistical properties of the non-hierarchical planar three-body problem, relevant to astrophysical systems with nearly planar dynamics, including protoplanetary disks and AGN disks. Using the Flux-based statistical theory of the three-body problem, previously studied in three dimensions, we derive theoretical predictions for several statistical observables in the planar case. Focusing on ergodic disintegration outcomes, we compare these predictions directly with numerical simulations and contrast the results with the corresponding unconstrained three-dimensional case. Our analysis is based on one million simulations for each of eight distinct mass sets. We examine escape probabilities, properties of marginal escape events, eccentricity distributions, lifetime distributions, and relative prevalence of prograde and retrograde escapes. While several of the theoretical predictions are in good agreement with the simulations, others exhibit unexpected discrepancies. We discuss possible explanations for these deviations.
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All authors Yogesh Dandekar, Ethan Springer, Shoval Zard, Alessandro Alberto Trani, Barak Kol, Ofek Birnholtz
Optics
Spatially or temporally resolved phase-based optoretinography with actively-tracked point-scanning optical coherence tomography
Léo Puyo, Jonas Franke, Felix Zeisberger et al. (+2 more)
Optoretinography is a promising approach to measure visual function but its clinical translation has remained confined to research settings due to demanding hardware requirements. Here, we demonstrate that high-quality phase-based optoretinography can be performed using conventional point-scanning spectral-domain optical coherence
tomography. We show that the need for high imaging speed can be circumvented by accurate sampling of phase changes at consistent spatial location. Light-evoked outer-segment expansion could be temporally resolved in B-scan series acquired at a fixed position when filtering off-location B-scans, and spatially resolved in volumes acquired at rates as low as 1~Hz. These results indicate that the technical barrier for phase-based optoretinography is substantially lower than previously assumed and pave the way toward broad clinical translation.
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All authors Léo Puyo, Jonas Franke, Felix Zeisberger, Roland Rocholz, Gereon Hüttmann
Applied Physics
Towards an effective medium theory for in-vivo Magnetic Resonance: Characterizing Admissible Magnetization Dynamics
Alessandro Sbrizzi, Miha Fuderer and Ray Sheombarsing
The classical Bloch equation forms the foundation of
magnetic resonance theory but may be insufficient to capture the complex effective dynamics observed in heterogeneous materials such as biological tissue. Here an effective-medium strategy is proposed to describe
magnetic resonance dynamics from observations at macro-scale (order 1 mm$^3$). In this framework, the classical Larmor torque is retained while the relaxation term is replaced by a general nonlinear field (i.e. the effective medium term). This field is required to preserve key physical properties, including rotational
symmetry, global stability of thermal
equilibrium, and dissipativity. These requirements lead to a complete characterization of admissible relaxation fields and provide a constructive framework for generating nonlinear relaxation models. The resulting theory recovers classical Bloch dynamics as a special case and provides a principled foundation for effective-medium descriptions of
magnetic resonance phenomena.
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Applied Physics
Arctic Dispersion Interruption Phenomenon and Sound Source Depth Estimation
Weng Jinbao, Yang Yanming, Chen Benqing et al. (+2 more)
The sound speed profile in the deep Arctic Ocean causes the surface layer to form a normal mode waveguide. When the depth of the sound source or receiver is near a node of the eigenfunction, the source cannot excite the mode, or the receiver cannot detect it, resulting in the modal amplitude at the receiver being approximately zero. This manifests as a dispersion interruption in the dispersion structure, which can be observed through time-frequency analysis of the received acoustic signal. Based on the interruption frequency identified from the received signal, combined with the relationship between node depth and modal frequency calculated from the ocean sound speed profile, the source depth can be estimated if the receiver depth is known. The phenomenon of dispersion interruption and the method of estimating source depth have been validated through simulations and experiments.
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All authors Weng Jinbao, Yang Yanming, Chen Benqing, Xu Dewei, Zhou Hongtao
Computational Physics
Cartesian tensor equivariant machine-learning force field for spin-dependent atomistic simulations
Junjie Wang, Yijie Zhu, Zhongwei Zhang et al. (+5 more)
Magnetic materials exhibit an intricate coupling between atomic structure and
spin degrees of freedom, posing a fundamental challenge for atomistic simulations across experimentally relevant length and time scales. Here we introduce HotPP-
Spin, a
spin-dependent extension of HotPP for
magnetic machine learning interatomic potentials, built on Cartesian tensor equivariant message passing. Atomic
magnetic moments are treated as explicit axial-vector degrees of freedom, while spatial-inversion and time-reversal parities are propagated through the tensor couplings. This construction provides a unified representation of exchange-dominated and
spin-orbit-induced interactions without imposing predefined analytical interaction forms. A scalar
spin-dependent potential energy surface yields energy-conserving atomic forces and
magnetic effective fields through differentiation.
Benchmarks spanning collinear magnetism, noncollinear magnetism, and
spin-orbit-coupling-induced
magnetic anisotropy show that HotPP-
Spin accurately describes
magnetic energy landscapes,
magnetic forces, and
magnetic-order-dependent energy-volume relations within the same general framework. For H-phase monolayer VSe\(_2\),
stochastic spin-dynamics simulations using the learned
magnetic effective fields locate the finite-size
magnetic ordering crossover at 415–435~K, in close numerical agreement with the reported experimental value of \(418.5\pm7.8\)~K. These results establish Cartesian tensor message passing as a general route for connecting first-principles
magnetic energetics with large-scale atomistic simulations of coupled structural and
spin phenomena.
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All authors Junjie Wang, Yijie Zhu, Zhongwei Zhang, Zhiyue Guo, Xudong Zhu, Lixin He, Chi Ding, Jian Sun
Optics · Cross-listed from quant-ph
Quantum-interference metrology of dissipative Kerr solitons
Yun-Ru Fan, Yong Geng, Ji Liu et al. (+9 more)
Dissipative Kerr
solitons in optical microresonators underpin chip-scale frequency combs with applications ranging from coherent telecommunications to precision spectroscopy. Yet the characterization of their intrinsic femtosecond temporal structure remains challenging, as the low pulse energy and broad spectral bandwidth necessitate optical amplification and careful dispersion compensation in conventional ultrafast diagnostics, both of which can significantly distort the waveform. Here we demonstrate a
quantum-interference metrology of microcomb
solitons based on Hong-Ou-Mandel interference. By attenuating the
soliton stream to the single-
photon level and measuring fourth-order interference, we directly retrieve near transform-limited pulse durations without amplification or dispersion management, remaining accurate even after propagation through 25 km of standard fiber. The same interferogram also provides direct access to the temporal separations in multi-
soliton states by converting inter-
soliton separations into additional interference dips at corresponding delays, enabling sub-picosecond characterization of their intracavity temporal structure. This
quantum-inspired paradigm introduces a fundamentally new metrological approach that is immune to amplification and dispersion distortions, offering a powerful tool for the characterization of complex
soliton physics.
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All authors Yun-Ru Fan, Yong Geng, Ji Liu, Yong-Jun Huang, Hai-Zhi Song, Hao Li, Li-Xing You, Heng Zhou, Kun Qiu, Kai Guo, Guang-Can Guo, Qiang Zhou
Optics
Sensitivity Comparison of Microwave-Frequency and Optical Fibre Interferometry Based on State-of-the-Art Components
Georgios Aias Karydis, Marco Fasano, Paola Parolari et al. (+3 more)
We compare the sensitivity of fibre interferometers to vibrations using microwave oscillators and state of the art
lasers over distances up to 70 km. High spectral purity
lasers outperform only above 10 Hz, highlighting microwave advantages at low frequencies and the potential of hybrid microwave optical interferometry systems
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All authors Georgios Aias Karydis, Marco Fasano, Paola Parolari, Pierpaolo Boffi, Charis Mesaritakis, Adonis Bogris
Fluid Dynamics
Coexisting chaos and order in micro-textured elastic flows
Giulio Foggi Rota, Ricardo Arturo Lopez de la Cruz, Simon J. Haward et al. (+2 more)
Viscoelastic fluid flows over micro-textured surfaces - densely covered by slender protrusions like cilia lining the body airways or villi covering the intestinal epithelium - underpin essential biological processes including transport, mixing, and absorption. Despite their ubiquity, the dynamics generated by the interplay between fluid elasticity and these complex geometries remain largely unexplored. Here we combine fully resolved numerical simulations with microfluidic experiments to reveal the flow dynamics established above dense arrays of microscopic pillars (canopies) immersed in the low-Reynolds-number flow of a viscoelastic
liquid. We observe that the flow above the canopy tips spontaneously develops elastic
turbulence. Remarkably, the chaotic state coexists with elastic waves emerging from the coupling between fluid elasticity and the heterogeneous shear induced by the canopy geometry. These ordered fluid motions persist across a broad range of flow conditions and canopy configurations. Our results demonstrate that coherent wave propagation and elastic
turbulence are complementary manifestations of viscoelastic fluid flow. Beyond their fundamental significance, these mechanisms have broad implications for transport in biological and engineered environments, and reveal how structured geometries can harness the spontaneous dynamics of viscoelastic
liquids to manipulate complex flows.
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All authors Giulio Foggi Rota, Ricardo Arturo Lopez de la Cruz, Simon J. Haward, Amy Q. Shen, Marco Edoardo Rosti
Physics and Society · Cross-listed from cs.DL
SoniMet - A tool for sonifying and visualizing the performance of single researchers
Tim Waterfield and Lutz Bornmann
For centuries, the scientific community has predominantly relied on visual tools to communicate empirical results and complex
datasets. While visual representations dominate bibliometric analyses, the human auditory system possesses sensitive capacities for processing complex temporal information, distinguishing intricate patterns, and tracking parallel data streams. Data sonification translates data relations into acoustic signals, offering an alternative method for data exploration, pattern recognition, and scientific communication. This paper applies this concept to the field of bibliometrics through metrics sonification-the auditory translation of bibliometric information-and introduces SoniMet (Sonifying Metrics), a web-based tool designed to visualize and sonify the publication and citation data of individual scientists (see https://sonimet.kennebec.co.uk). SoniMet connects to the OpenAlex database to retrieve bibliometric records and displays them on an interactive chronological timeline. The tool employs direct parameter mapping to translate citation impact indicators into non-
speech sound: field-weighted citation impact and citation counts determine the pitch and volume of a synthesized note and are mapped to the acoustic echo strength. Although SoniMet expands the methodological toolkit for research evaluation, current limitations include its restriction to individual scholar profiles and the challenge of integrating transient audio files into traditional, text-based scientific publishing workflows. Future empirical user studies are necessary to systematically evaluate the analytical utility and cognitive benefits of metrics sonification compared to established visual methods.
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Atomic Physics · Cross-listed from hep-ph
Spin-dependent fermion potentials from mixed tensor couplings of massive spin-1 and spin-2 bosons
D. Khadka and V.V. Flambaum
Searches for weak
spin-dependent forces are commonly interpreted in terms of a basis of sixteen rotationally invariant two-
fermion potentials, including potentials which violate parity (P) and time-reversal (T) invariance. We derive finite-range coordinate-space potentials generated by a massive
spin-1
boson with vector, axial-vector, tensor, and pseudotensor couplings to Dirac
fermions. In addition to the familiar vector–vector, vector–axial-vector, and axial-vector–axial-vector interactions, we obtain the mixed vector–tensor, vector–pseudotensor, axial-vector–tensor, and axial-vector–pseudotensor potentials, together with tensor–tensor, tensor–pseudotensor, and pseudotensor–pseudotensor terms. We retain the contact terms needed in atomic-scale applications and give compact expressions that include both orderings of inequivalent
fermion vertices. We then extend the analysis to a massive
spin-2 mediator described by a symmetric Fierz–Pauli field. Besides the conventional coupling to the conserved
fermion energy–momentum tensor, we consider a symmetric axial-tensor current. Its nonconservation for massive
fermions makes the longitudinal
spin-2 helicities contribute to axial-tensor–axial-tensor exchange. The leading minimal
spin-2 interactions are either P,T even or P odd and T even; in particular, they do not generate a T-odd potential. We map the resulting interactions onto the sixteen-potential Dobrescu–Mocioiu basis and use this mapping to translate existing experimental constraints into numerical limits on
spin-1 and
spin-2 coupling products in the small- and large-mediator-mass regimes, together with representative limits at finite mediator masses. The derived relations between the
boson-exchange coupling constants and the coefficients of the basis potentials also allow published exclusion curves to be rescaled to arbitrary mediator masses.
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