Optics
Large differential attosecond delays in solid state photoemission
Andreas Gebauer, Walter Enns, Sergej Neb et al. (+11 more)
Time-resolved photoelectron spectroscopy provides access to the electronic structure and non-
equilibrium electron dynamics in matter. At solid surfaces photoemission dynamics can be investigated on its natural time scale by measuring attosecond time delays of emitted electrons. Photoelectrons with final state energies of several tens of eV need tens to hundreds of attoseconds to be released into the
vacuum. Competing effects determine the emission dynamics and, hence, the full picture of the process is still under debate. The rather large energy differences between the final states probed in commonly reported relative photoemission delays obscure their complex fine structure and hinders the interpretation of the measurements. Here we report differential attosecond delays $\tau_{\mathrm{DAD}}$, i.e., relative photoemission delays for energetically close-lying
spin-orbit split states. Differential attosecond delays on the order of 30 to 100 as for Bi 5d, Te 4d, and Se 3d core level photoemission from Bi$_2$Te$_3$ and Bi$_2$Se$_3$ can neither be attributed to intra-atomic delays, nor to ballistic transport and subsequent emission. Instead, calculations based on the one-step photoemission theory reveal that photoemission delays vary strongly on the energy scale of the
spin-orbit splitting and quantitatively match experimental observations. This strong variation arises from multiple scattering at the surface leading to final states that involve both evanescent and propagating Bloch waves. Their relative amplitudes vary strongly affecting thereby the timing of the photoemission event since evanescent and propagating components exhibit inherently different dynamics.
Read the full abstract ▾
All authors Andreas Gebauer, Walter Enns, Sergej Neb, Tillmann Schabbehard, Luis Maschmann, Stefan Muff, J. Hugo Dil, Ulrich Heinzmann, Stephan Fritzsche, Ricardo Diez Muiño, Pedro M. Echenique, Nikolay M. Kabachnik, Eugene E. Krasovskii, Walter Pfeiffer
Fluid Dynamics
Adaptive shape control for microswimmer navigation in turbulence
Jingran Qiu, Lorenzo Piro, Luca Biferale et al. (+3 more)
Navigation in turbulent environments is a fundamental challenge for biological and artificial microswimmers. While most existing studies focus on adapting motility or steering, the role of active morphological changes in
navigation remains poorly explored. Here, we investigate a shape-changing spheroidal microswimmer tasked with maximising its displacement from an initial position in two-dimensional
stochastic and turbulent flows. Using reinforcement learning (RL), the microswimmer learns to adapt its aspect ratio based on its orientation and local velocity-gradient signals. The learned strategies outperform fixed-shape and short-time-optimal baselines across different flow regimes and remain effective when transferred from
stochastic flows to fully resolved
turbulence. Guided by the learned policies, we propose a minimal analytical model that captures the essential
navigation mechanisms and reproduces the performance across flow regimes. These results show that adaptive morphology provides a robust and physically interpretable control paradigm for microswimmer
navigation in complex flows.
Read the full abstract ▾
All authors Jingran Qiu, Lorenzo Piro, Luca Biferale, Massimo Cencini, Bernhard Mehlig, Kristian Gustavsson
Optics
Nanosecond wavefront shaping to focus through agitated turbid media
Hugo Lassiette, Léa Krafft, Geoffrey Maulion et al. (+9 more)
Multiple scattering rapidly scrambles optical fields in fog, snow and turbid water, causing op- timized wavefront corrections to become obsolete on microsecond timescales. Although wavefront shaping enables focusing through static scattering layers, closed-loop control in dynamically evolving media has remained experimentally challenging because the correction bandwidth must approach the intrinsic decorrelation rate of the speckle. Here, we demonstrate closed-loop wavefront shaping with 32 independent degrees of freedom in an agitated turbid medium exhibiting sub-microsecond decorrelation. The medium thickness exceeds the transport mean free path, meaning the far-field speckle autocorrelation is limited to a diffraction-sized grain. Despite the microsecond decorrelation and this multiple-scattering regime, stable focusing is maintained as the correction cycle approaches the intrinsic dynamics of the medium. These results establish an experimentally accessible regime for coherent wave control in rapidly evolving complex media.
Read the full abstract ▾
All authors Hugo Lassiette, Léa Krafft, Geoffrey Maulion, Jérôme Henrion, Julien Houy, Yann Lucas, Laurent Lombard, Bastien Rouzé, Vincent Michau, Willem L. Vos, Sébastien Popoff, Serge Meimon
Applied Physics · Cross-listed from nlin.CD
Non-Normal Route to Chaos
D. Sornette, V.R. Saiprasad and V. Troude
Deterministic chaos is usually associated with local spectral expansion: Jacobian
eigenvalues are expected to exceed unity somewhere on the attractor. We show that this view is incomplete in dimensions d>1. For non-normal Jacobians, pointwise spectral stability can suggest everywhere local contraction, while non-orthogonal eigenvectors still allow transient singular-vector amplification. We construct four low-dimensional deterministic maps realizing this mechanism: partition-reinjected, phase-prescribed, feedback-driven, and affine-reinjected non-normal routes to chaos. In all cases, the instantaneous Jacobian remains spectrally stable on the attractor, with
eigenvalues fixed inside the unit disk, while increasing non-normality drives the maximal Lyapunov exponent through zero. The positive exponent therefore describes sustained asymptotic chaos, not transient chaos. Across the four classes, the common signature is spectral radius $\rho_{\mathrm{traj}}^{\max}<1$, singular value $\sigma_{\mathrm{traj}}^{\max}>1$ maximum Lyapunov exponent $\lambda_1>0$, and an increase of attractor dimension. These examples identify non-normality and recurrent reinjection of transiently amplified directions as a deterministic route to chaos distinct from
eigenvalue instability.
Read the full abstract ▾
Instrumentation and Detectors
Broad frequency tuning of a Nb$_{3}$Sn superconducting microwave cavity for dark matter searches
D. Maiello, R. Di Vora, D. Ahn et al. (+10 more)
We demonstrate a novel broad-frequency tuning mechanism for superconducting microwave cavities designed for dark matter searches. Using a Nb$_3$Sn-coated cigar-shaped cavity operating at approximately 9\,GHz, we achieve continuous frequency tuning exceeding 1\,GHz by mechanically separating the two cavity halves: a "tuning-by-opening" technique. Finite-element method simulations predict that radiative losses do not degrade the quality factor even for large openings, as a closed cavity with an intrinsic quality factor of $10^7$ maintains this value for apertures up to 9\,mm, corresponding to a tuning range from 9.0 to 7.5\,GHz. Experimental validation using both copper ring spacers and a continuous sliding mechanism confirms $Q_0$ values exceeding the dark matter quality factor across the entire explored frequency range, despite mechanical imperfections and film non-uniformities. This tuning approach avoids inserting elements into the resonant volume, making it particularly suitable for high-Q superconducting cavities in
axion haloscope experiments and readily applicable to REBCO-based implementations capable of operating in multi-tesla
magnetic fields.
Read the full abstract ▾
All authors D. Maiello, R. Di Vora, D. Ahn, G. Carugno, R. Cervantes, B. Giaccone, A. Ortolan, S. Posen, G. Ruoso, G. Sardo Infirri, B. Tennis, S. Tocci, C. Braggio
Instrumentation and Detectors
SiPM non-linearity studies in beam tests with scintillating crystals
Zhiyu Zhao, Dejing Du, Shu Li et al. (+4 more)
High-granularity homogeneous electromagnetic calorimeters based on scintillating
crystals and silicon photomultipliers (SiPMs) are a promising option for future $e^{+}e^{-}$
Higgs factories, where both excellent energy resolution and a very large dynamic range are required. In this work, the non-linear response of high-pixel-density SiPMs with pixel pitches of 6–10~$\mu$m coupled to BGO and BSO
crystals is studied under realistic beam conditions. A dual-end readout scheme with an attenuated reference SiPM was employed to precisely calibrate the deposited energy and the corresponding number of photoelectrons over a wide dynamic range. Beam tests were carried out at the CERN SPS H2 beamline using high-energy electrons, with a tungsten pre-shower and variable incident angles to enhance energy deposition. The measurements directly quantify the non-linear response of SiPMs to scintillation light over an extended dynamic range. For BGO-coupled Hamamatsu SiPMs, deviations from linearity of about 20% are observed at $5\times10^{5}$ photoelectrons, while larger deviations are measured for the tested NDL devices and for configurations with faster BSO scintillation.
Read the full abstract ▾
All authors Zhiyu Zhao, Dejing Du, Shu Li, Yong Liu, Baohua Qi, Jack Rolph, Haijun Yang
Classical Physics
Unimode material based low-frequency underwater acoustic isolation
Yu Wei, Binghao Zhao, Fen Du et al. (+2 more)
Extremal materials are a specific class of Cauchy materials whose elasticity tensor has one or more zero
eigenvalues. Each zero
eigenvalue corresponds to a soft mode requiring zero strain energy, while non-zero
eigenvalues correspond to hard modes that cost energy. According to the number, N, of zero
eigenvalues, these materials can be referred to as unimode (N=1), bimode (N=2), etc. Extremal materials have enabled novel functions beyond conventional Cauchy media, e.g.,
phonon polarizers, Rayleigh wave isolators and
underwater acoustic cloaks. These functions typically require a single extremal material. Interfaces between two extremal materials exhibit rich wave behaviors, yet have been seldom explored. Here, we proposed the concept of complementary extremal materials, i.e., the soft mode of one extremal material is a hard mode of the other. As one example, we study the interface between an isotropic unimode material and an isotropic bimode material. We show that the interface allows perfect mode conversion from longitudinal waves to transverse waves. A low-frequency
underwater acoustic
insulator based on complementary extremal materials is proposed. Our finding has been verified with designed metamaterials and using effective-medium modeling. This work demonstrates the potential of complementary extremal materials in controlling elastic wave polarization and waterborne sound.
Read the full abstract ▾
All authors Yu Wei, Binghao Zhao, Fen Du, Yi Chen, Gengkai Hu
Chemical Physics
Triplet-Pair Character of the $2^1A_g$ Dark State of Polyenes
Alexandru G. Ichert and William Barford
We define and calculate the triplet-pair population of the $2^1A_g$ dark state in polyenes, as predicted by the $\pi$-electron Pariser-Parr-Pople (PPP) model, for chains of 8 to 14 C-atoms and Coulomb interaction parameter between 4-14 eV. Our definition of the triplet-pair population is motivated by a two-particle model of the $2^1A_g$ state. We use DMRG to solve the PPP model and we exploit the MPS representation of the DMRG wavefunction to compute the triplet-pair population. Using our results for short chain sizes, we predict a finite-size scaling value of the triplet-pair population of ca. 75% for realistic Coulomb interactions for polyene chains. Our results agree with other theoretical work on the doubly-excited character of polyenes, and represents further evidence that the $2^1A_g$ state is predominantly triplet-pair in character - with implications for singlet fission mechanisms in polyenes.
Read the full abstract ▾
Optics
Fourier Transform Infrared microspectroscopy-based super-resolution virtual staining of unlabeled tissues by pixel Diffusion Transformer
Yudong Tian, Xiangyu Zhao, Yuqing Liu et al. (+2 more)
Here, we present a
diffusion transformer (DiT)-based pixel super-resolution virtual staining approach to transform low-resolution FTIR microspectroscopic images of the unstained tissues into corresponding high-resolution H&E-stained images. Unlike conventional conditional DiT architectures, this method models the transformation from FTIR images to H&E-stained images as a
stochastic Brownian bridge process and directly learns the cross-domain translation in pixel space by means of a large-patch
Transformer. When applied to FTIR images of unlabeled human lung tissue samples, the proposed method successfully transforms them into high-resolution H&E-stained images, achieving a 4 times pixel-level super-resolution. Additionally, by partitioning images into large patches, our method achieves a fourfold improvement in inference speed compared with traditional U-Net-based
diffusion models, without compromising the quality of generated images. This super-resolution virtual staining method provides a rapid and effective solution for generating high-resolution, clinically usable H&E-stained images from infrared spectroscopic images, which can significantly facilitate the incorporation of FTIR microspectroscopy into clinical histological scenarios.
Read the full abstract ▾
All authors Yudong Tian, Xiangyu Zhao, Yuqing Liu, Bofei Yang, Chongzhao Wu
Atomic Physics
Semiclassical description of Intermolecular Coulombic Electron Capture in solutions
Nicolas Sisourat
In this work, we present a semiclassical approach to model Intermolecular Coulombic Electron Capture (ICEC) in aqueous solutions using molecular dynamics simulations with OpenMM. We investigate the behavior of an excess electron in the presence of cations (Fe$^{3+}$) in water, focusing on the influence of electron energy and cation concentration on the ICEC
quantum yield. Our simulations reveal that the ICEC
quantum yield approaches unity at higher concentrations and initial electron energies, while it decreases at lower concentrations due to electron energy loss before reaching the cation.
Read the full abstract ▾
Biological Physics · Cross-listed from math.AP
Valeria Cuentas and Elio Espejo
Cells encounter a diverse array of physical and chemical signals as they navigate their natural surroundings. However, their response to the simultaneous presence of multiple cues remains elusive. Particularly, the impact of topography alongside a chemotactic gradient on
cell migratory behavior remains insufficiently explored. In this paper, we investigate the effects of topographical obstacles during chemotaxis. Our approach involves modifying the Keller-Segel model, incorporating a spatially dependent coefficient of chemotaxis. Through our analysis, we demonstrate that this coefficient plays a crucial role in preventing blow-up phenomena in
cell concentration.
Read the full abstract ▾
Computational Physics · Cross-listed from cond-mat.stat-mech
Percolation on multifractal, scale-free weighted planar stochastic porous lattice
Proshanto Kumar and Md. Kamrul Hassan
We introduce the Weighted Planar
Stochastic Porous
Lattice (WPSPL), a geometrically disordered substrate generated by iteratively subdividing a unit square. At each step a block is selected with probability proportional to its area, divided into four parts, and one sub-block is retained (removed) with probability $q$ ($1-q$). We show analytically that the WPSPL exhibits multifractality for each of its infinitely many nontrivial conserved quantities and demonstrate numerically that its snapshots at different times are statistically self-similar. The dual of the
lattice forms a complex network with a power-law degree distribution. Motivated by these properties of this porous
lattice, we study bond percolation on the WPSPL, determine the percolation threshold, and estimate the critical exponents $\alpha$, $\beta$, and $\gamma$ associated with the specific heat, order parameter, and susceptibility, respectively. The exponents vary continuously with $q$, reflecting a family of distinct universality classes as the global dimension of the
lattice depends on $q$. Remarkably, the Rushbrooke inequality, $\alpha + 2\beta + \gamma \ge 2$, is satisfied in near equality. Notably, the nonporous case ($q=1$) has a global dimension $2$ but lies outside the universality class of conventional two-dimensional
lattices. Our results highlight how
geometric disorder, multifractality, scale-free coordination number disorder, and porosity produce unconventional critical behavior.
Read the full abstract ▾
Applied Physics
Loss-Optimized Reconfigurable Nonlocal Metasurface-aided Cavity Antenna
Minwoo Cho and Minseok Kim
This paper presents the design and experimental demonstration of a reconfigurable cavity excited nonlocal metasurface
antenna capable of wide angle dynamic beam steering. The
antenna is synthesized using a volume surface integral equation based framework that rigorously captures nonlocal mutual coupling among metasurface unit
cells. To ensure physical consistency, the numerically characterized resistance and reactance relationship of the tunable unit
cells is directly incorporated into the synthesis, enabling precise far-field synthesis while minimizing Ohmic losses. The proposed approach is applied to a 10 GHz cavity fed metasurface
antenna composed of 24 independently controlled varactor-loaded unit
cells. Numerical simulations and near-field measurements demonstrate stable beam steering with a range of 80 degrees across broadside with excellent agreement between measured and simulated radiation patterns. These results confirm the effectiveness of the proposed framework for the realization of compact, reconfigurable cavity-excited metasurface
antennas.
Read the full abstract ▾
Computational Physics · Cross-listed from cond-mat.mtrl-sci
Non-Markovian heat production in ultrafast phonon dynamics
Fredrik Erikssonm Yulong Qiao, Erik Fransson, R. Matthias Geilhufe et al. (+1 more)
High-intensity THz
laser pulses enable the light-mediated control of
lattice vibrations by resonantly driving selected
phonon modes. On ultrafast timescales,
memory effects influence the
phonon dynamics and must be accounted for to describe the heat production associated with energy dissipation. Here, we establish a microscopic framework for non-Markovian
phonon dynamics by deriving the noise and dissipation kernels governing a driven
phonon mode. Using large-scale molecular dynamics simulations, we reconstruct these kernels directly from the many-body
lattice dynamics and determine the corresponding heat production rate. Our results provide a quantitative picture of the crossover between Markovian and non-Markovian dynamics on picosecond timescales and show how the finite bandwidth of the driving field limits the dynamically relevant bath spectrum. Furthermore, we demonstrate that thermodynamic quantities such as heat production can be inferred directly from the dynamics of an individual
phonon mode, enabling their experimental measurement using time-resolved spectroscopy.
Read the full abstract ▾
All authors Fredrik Erikssonm Yulong Qiao, Erik Fransson, R. Matthias Geilhufe, Paul Erhart
Chemical Physics · Cross-listed from quant-ph
Classically Driven Hybrid Quantum Algorithms with Sequential Givens Rotations for Reduced Measurement Cost
Benjamin Mokhtar, Noboru Inoue and Takashi Tsuchimochi
Quantum algorithms for electronic-structure simulations are actively being developed, yet many hybrid
quantum-classical approaches are bottlenecked by the measurement overhead associated with large molecular
Hamiltonians. Here we introduce a diagonalization-driven framework that progressively drives the electronic
Hamiltonian toward a (block-)diagonal form in the Slater-determinant basis using sequential Givens rotations. In contrast to Schrödinger-picture methods that variationally optimize a wave function, our approach adopts a Heisenberg-picture viewpoint: the
Hamiltonian is iteratively transformed, and rotation angles are determined classically from low-dimensional effective blocks, reducing the
quantum workload to a small, fixed set of
matrix-element measurements per iteration. Candidate generators are estimated via approximate Baker-Campbell-Hausdorff updates with truncation and cumulant-based approximations that control
Hamiltonian growth, complemented by
stochastic selection to avoid stagnation. We further introduce an angle-merging procedure that reduces
circuit depth by consolidating repeated small-angle rotations. We
benchmark the framework on N$_2$ and strongly correlated hydrogen systems, assessing convergence behavior, residual-structure diagnostics, measurement-accuracy trade-offs,
circuit costs, and robustness under finite sampling.
Read the full abstract ▾
Chemical Physics
Mixture of experts architectures for machine learning interatomic potentials
Yuzhi Liu, Duo Zhang, Anyang Peng et al. (+3 more)
Machine Learning Interatomic Potentials (MLIPs) enable accurate large-scale atomistic simulations, yet improving their expressive capacity efficiently remains challenging. Here we systematically investigate Mixture-of-Experts (MoE) and Mixture-of-Linear-Experts (MoLE) architectures within the DPA3 framework for MLIPs and analyze the effects of routing strategies and expert designs. We show that sparse activation combined with shared experts yields substantial performance gains, and that nonlinear MoE formulations outperform MoLE when shared experts are present, underscoring the importance of nonlinear expert specialization. Furthermore, element-wise routing consistently surpasses configuration-level routing, while global MoE routing often leads to numerical instability. The resulting element-wise MoE model consistently outperforms all DPA3-based baselines across the OMol25, OMat24, and OC20M
benchmarks. Analysis of routing patterns reveals chemically interpretable expert specialization aligned with periodic-table trends, indicating that the model effectively captures element-specific chemical characteristics for precise interatomic modeling.
Read the full abstract ▾
All authors Yuzhi Liu, Duo Zhang, Anyang Peng, Weinan E, Linfeng Zhang, Han Wang
Optics
Interleaved diffractive networks for information transfer through random diffusers
Yuhang Li, Yiyang Wu, Shiqi Chen et al. (+2 more)
Transferring optical information through random diffusers is a critical yet challenging task. In this work, we introduce a cascaded diffractive optical network for information transfer through random and unknown diffusers, achieved through a series of passive, structured layers physically interleaved within the scattering medium. These interleaved diffractive layers are optimized to mitigate the scattering process without requiring digital computing. The performance of this all-optical system was quantified as a function of several physical parameters, including the diffractive processor's depth, the physical layout of the diffractive layers, and the statistical properties of the scattering medium. To further enhance the performance and robustness of information transfer through a scattering medium, we also developed a hybrid (optical-digital) system that coupled the diffractive processor with a jointly trained digital neural network, which was shown to achieve superior reconstruction fidelity even when the input object information was subjected to unknown random rotations, shifts, and scaling. We also experimentally validated this system using a fabricated multi-layer diffractive system in the visible spectrum, demonstrating reliable information recovery through random diffuser layers. Our numerical and experimental results demonstrate the capabilities of an interleaved diffractive processor architecture to recover optical information through volumetric diffusive media, which can find applications in biomedical imaging, telecommunications, and remote sensing.
Read the full abstract ▾
All authors Yuhang Li, Yiyang Wu, Shiqi Chen, Xilin Yang, Aydogan Ozcan
Plasma Physics
MMS Observations of Kinetic Alfvén Wave Turbulence and Steep Kinetic-Range Spectra in the Outer Plasma Sheet Boundary Layer
Mani K Chettri, Rupak Mukherjee and Hemam D. Singh
Energy dissipation and particle acceleration in the collisionless magnetotail
plasma remain incompletely understood. We report observations of Kinetic Alfvén Wave (KAW)
turbulence and parallel electric fields ($E_{\parallel}$) in the outer
Plasma Sheet Boundary Layer (PSBL) using high-resolution burst-mode data from the Magnetospheric Multiscale (MMS) mission. For a crossing on May 31, 2017, we identify broadband KAW
turbulence characterized by a normalized electric-to-
magnetic field ratio $\mathcal{R}=|\delta E_{\perp}|/(v_A|\delta B_{\perp}|)=2.5\pm1.2$ exceeding the MHD limit, a spectral break near ion scales, a steep kinetic-range spectral slope ($\alpha=-3.48\pm0.13$), and low
magnetic compressibility ($C_{\parallel}\approx0.03$). We observe impulsive $E_{\parallel}$ structures up to 15 mV/m and ion density fluctuations up to 68% during enhanced wave activity. The steep spectrum, compared with undamped KAW predictions ($-7/3$ to $-8/3$), is consistent with substantial energy removal at kinetic scales. The near-zero correlation between the KAW-band filtered $E_{\parallel}$ waveform (0.18 to 2.0 Hz) and ion density fluctuations ($r\approx0.04$) indicates no simple linear, zero-lag correspondence under the adopted processing. Together with bursty energy-conversion proxies, the observations are consistent with localized field-particle energy exchange and collisionless damping of KAW
turbulence in the intermediate-beta outer PSBL. A specific damping channel, such as Landau damping, is not uniquely constrained by the present diagnostics.
Read the full abstract ▾
Optics · Cross-listed from astro-ph.IM
Structural Design and Performance Analysis of Laser Transmitting Telescope for Space Gravitational Wave Detection
Long Yongtao, Mo Yan, Cao Shengyi et al. (+8 more)
The spaceborne
laser emission
telescope is a core and critical component of the space gravitational wave detection system.Compared with ground-based
telescopes, the on-orbit space environment is more complex and harsh, presenting higher technical challenges for the design of the optical system and structure - both optical design and structural design face considerable difficulties. To meet the requirements of space gravitational wave detection, this paper designs a
laser emission
telescope based on an off-axis four-mirror configuration, with a capture field of view of 300{\mu}rad, an optical transmission efficiency of 86.3%, and an optical path stability index of TTL<0.025 nm/{\mu}rad. During the design process, based on existing theories and engineering experience, the primary mirror thickness optimization and lightweight structural design were completed, and a flexible support scheme was adopted to achieve a primary mirror surface figure accuracy of 9.42 nm; the total mass of the entire
telescope (excluding mirrors) is only 3.845 kg. Multi-dimensional finite element analysis was conducted on the
telescope under actual working conditions: the strength of the
telescope's support materials was verified under self-weight and 10G
gravity loads; after removing the rigid body displacement of the mirrors using Zernike
polynomials, the surface deformation of the primary mirror was controlled within 1/30 wavelength. In the thermal stability analysis, the structural deformation of the
telescope under a temperature change of 100 degree celsius was simulated, and key indicators such as eccentricity and tilt between the mirrors all meet the optical design requirements. In the modal analysis, the first-order natural frequency of the
telescope reaches 200 Hz under both self-weight and weightless conditions, demonstrating excellent dynamic stability.
Read the full abstract ▾
All authors Long Yongtao, Mo Yan, Cao Shengyi, Cao Jiamin, Zhao Lujia, Wang Haibo, Wang Shuangbao, Tan Hao, Liu Xiaohong, Wang Dawei, Ma Donglin
Atomic Physics
Enhanced Rydberg Blockade through RF-tuned Förster Resonance
Lukas Palm, Bowen Li, Yiming Cady Feng et al. (+2 more)
Enhancing interactions between Rydberg atoms is a key challenge in contemporary
quantum technologies. Stronger interactions enable faster Rydberg gates in digital processors and larger entangled states in analog simulation. Achieving the same interaction strength at lower principal
quantum number addresses current constraints in available Rabi frequency and field sensitivity in large scale tweezer or cavity QED experiments. Here, we demonstrate a new technique using AC Stark shifts from a microwave drive to tune into a Förster resonance, thereby modifying the interaction scaling with distance from $1/R^6$ to $1/R^3$. We validate enhanced Rydberg interactions (in strength and range) by probing cavity Rydberg polariton blockade at $n=44$ in $^{87}$Rb, improving from $g^{(2)}(0) = 1.0 (1)$ in the Van-der-Waals regime to $g^{(2)}(0) = 0.38 (1)$ in the dipolar regime on the Förster resonance. Importantly, our technique allows minimal shifts of the original Rydberg state, suppressing detuning errors in gate protocols while maintaining quadratic insensitivity to DC electric fields.
Read the full abstract ▾
All authors Lukas Palm, Bowen Li, Yiming Cady Feng, Marius Jürgensen, Jon Simon
Fluid Dynamics · Cross-listed from cs.RO
Unified Structural-Hydrodynamic Modeling of Underwater Underactuated Mechanisms and Soft Robots
Chenrui Zhang, Yiyuan Zhang, Yunfei Ye et al. (+3 more)
Underwater robots are widely deployed for ocean exploration and manipulation. Underactuated mechanisms are advantageous in aquatic environments because reducing actuator count lowers motor-leakage risk while introducing inherent mechanical compliance. However, accurate modeling of
underwater underactuated and soft robotic systems remains challenging, as it requires identifying high-dimensional structural and hydrodynamic parameters. In this work, we propose a trajectory-driven global optimization framework for unified structural-hydrodynamic modeling of
underwater multibody systems. Inspired by the Covariance
Matrix Adaptation
Evolution Strategy (CMA-ES), the proposed approach simultaneously identifies coupled elastic, damping, and distributed hydrodynamic parameters through trajectory-level matching between simulated and experimental motion. This enables high-fidelity reproduction of underactuated mechanisms and compliant soft robotic systems in
underwater environments, using as little as a single
video recording. We first validate the framework on a link-by-link underactuated multibody mechanism, demonstrating accurate identification of distributed hydrodynamic coefficients, with normalized end-effector position error below 5% across multiple trajectories, initial conditions, and both active-passive and fully passive configurations. The modeling strategy is further validated on an asymmetric octopus-inspired soft arm, confirming its effectiveness for compliant soft robotic systems. Finally, eight identified arms are assembled into a swimming octopus
robot, where the unified parameter set enables realistic whole-body behavior without additional retuning. These results demonstrate the scalability and transferability of the proposed structural-hydrodynamic modeling framework across
underwater underactuated and soft robotic systems.
Read the full abstract ▾
All authors Chenrui Zhang, Yiyuan Zhang, Yunfei Ye, Junkai Chen, Haozhe Wang, Cecilia Laschi
Optics
Ponderomotive Achromat for Electron Optics: Radially Polarized Annular Focusing and a Round-Lens Corrector Regime
Yuuki Uesugi and Yuichi Kozawa
Ponderomotive electron optics has attracted
attention because structured optical fields provide round-lens functionalities, including negative lens power and negative spherical aberration, that are difficult to achieve with conventional Einzel and solenoid lenses. How ponderomotive lenses disperse with electron energy, and whether that dispersion can be engineered for achromatization, have remained largely unexplored. Here we show that the transverse and longitudinal components of a vector optical field exhibit distinct energy dispersions because a relativistic correction modifies the effective lens action of the component polarized parallel to the electron velocity. In a radially polarized Bessel field coaxial with the electron beam, the two components form spatially co-located $J_1^2$- and $J_0^2$-type ponderomotive potentials whose relative weights depend on the electron energy, the Bessel cone angle, and the propagation direction of the light relative to the electrons. Using a local Abbe number defined in the energy domain, we find that this single field can operate as a self-achromatic round lens. We further construct zero-separation doublets—with a
magnetic objective-lens model or an azimuthally polarized Bessel lens—that simultaneously cancel the first-order axial chromatic- and third-order spherical-aberration coefficients at a fixed electron-optical focal length, with the useful solutions occurring for counter-propagating light. Finite-aperture calculations at optical wavelengths of $1064~\mathrm{nm}$ and $10.6~\mathrm{\mu m}$ relate the achievable probe size to the required optical power, and at $10.6~\mathrm{\mu m}$ they identify a low-energy, large-energy-spread regime in which the corrected doublets outperform the
magnetic objective-lens model. The required optical power is compatible with demonstrated near-infrared ultrashort-pulse sources.
Read the full abstract ▾
Classical Physics · Cross-listed from cond-mat.mes-hall
Band modulations and topological transitions in a one-dimensional periodic bead-on-string chain
Haocong Pan, Wei Wang and Chunling Liu
We study band modulations and topological transitions in a one-dimensional periodic bead-on-string chain. Using an exact transfer-
matrix formulation of the wave equation with periodically modulated mass density, combined with numerical spectral searches and tabletop experiments, we characterize band gaps and localized midgap states. We interpret these states by mapping the system to the Su-Schrieffer-Heeger (SSH) model and its low-energy (1+1)-dimensional Dirac theory. This framework reveals that the robust states are topological
solitons bound to boundaries or engineered domain walls in the Dirac mass. Through this mapping, we provide an intuitive account of how band structure controls topological phase changes in mechanically realizable
lattices.
Read the full abstract ▾
Applied Physics · Cross-listed from cond-mat.mes-hall
Designing Extremely Low-Power Topological Transistors with 1T'-MoS2 and HZO for Cryogenic Applications
Yosep Park, Yungyeong Park, Hyeonseok Choi et al. (+2 more)
Large-scale
quantum computing requires cryogenic electronic controllers such as control/readout
circuit and routing
circuit. However, current technologies face high power dissipation problems, hindering large-scale
qubit integration. Here, we theoretically propose extremely low-power cryogenic topological transistors, i.e., negative-capacitance topological
insulator field-effect transistors (NC-TIFETs). By combining a gate-field-induced two-dimensional 1T'-Molybdenum Disulfide (MoS$_2$) topological channel with a hafnium-zirconium
oxide (HZO) ferroelectric gate
insulator, NC-TIFETs exhibit an extremely steep-slope transfer curve and ultra-high transconductance at low drain voltage ($V_{\mathrm{D}}$). Therefore, NC-TIFETs are the compelling candidate for minimizing power dissipation in the cryogenic electronic interfaces essential for large-scale
quantum computing systems.
Read the full abstract ▾
All authors Yosep Park, Yungyeong Park, Hyeonseok Choi, Subeen Lim, Yeonghun Lee
Atmospheric and Oceanic Physics · Cross-listed from cs.LG
Designing probabilistic AI monsoon forecasts to inform agricultural decision-making
Colin Aitken, Rajat Masiwal, Adam Marchakitus et al. (+7 more)
Hundreds of millions of farmers make high-stakes decisions under uncertainty about future weather. Forecasts can inform these decisions, but available choices and their risks and benefits vary between farmers. We introduce a decision-theory framework for designing useful forecasts in settings where the forecaster cannot prescribe optimal actions because farmers' circumstances are heterogeneous. We apply this framework to the case of seasonal onset of monsoon rains, a key date for planting decisions and agricultural investments in many tropical countries. We develop a system for tailoring forecasts to the requirements of this framework by blending systematically benchmarked artificial intelligence (AI) weather prediction models with a new "evolving farmer expectations" statistical model. This statistical model applies
Bayesian inference to historical observations to predict time-varying probabilities of first-occurrence events throughout a season. The blended system yields more skillful Indian monsoon forecasts at longer lead times than its components or any multi-model average. In 2025, this system was deployed operationally in a government-led program that delivered subseasonal monsoon onset forecasts to 38 million Indian farmers, skillfully predicting that year's early-summer anomalous dry period. This decision-theory framework and blending system offer a pathway for developing
climate adaptation tools for large vulnerable populations around the world.
Read the full abstract ▾
All authors Colin Aitken, Rajat Masiwal, Adam Marchakitus, Katherine Kowal, Mayank Gupta, Tyler Yang, Amir Jina, Pedram Hassanzadeh, William R. Boos, Michael Kremer
Atmospheric and Oceanic Physics
Impacts of Jet Stream Structure on Cyclone Merging and Persistent Anticyclones: Insights from Dry Idealized Simulations
Mingfei Ren, Gan Zhang, Kai-Yuan Cheng et al. (+3 more)
Midlatitude jet streams exhibit substantial variability in latitude, width, and vertical depth on synoptic to multi-decadal timescales. While the upper-level dynamics of baroclinic waves have been extensively studied, the sensitivity of the extreme-generating, low-level phenomena to these variations remains underexplored. Here, we systematically investigate this sensitivity using dry, adiabatic idealized experiments with the GFDL FV3 dry dynamical core initialized with analytically specified jets. We identify jet variations that control synoptic-scale features of interest. Results indicate that poleward-shifted jets accelerate initial cyclone intensification and favor anticyclonic Rossby Wave Breaking (RWB). These wave-breaking tendencies are consistent with established baroclinic paradigms, validating the newly configured idealized simulations. Additionally, jet width regulates the likelihood of surface cyclone merging. Poleward-shifted, broader, and higher jets produce more frequent cyclone merging, generating intense wind extremes. Finally, we show that poleward-shifted, broad, deep jets dynamically precondition the flow for persistent stationary anticyclones in the absence of diabatic contributions. Together, these findings illustrate how changes in jet stream structure may modulate midlatitude weather extremes.
Read the full abstract ▾
All authors Mingfei Ren, Gan Zhang, Kai-Yuan Cheng, Lucas Harris, Talia Tamarin-Brodsky, Joseph Mouallem
Atomic Physics
QED corrections of orders $m\alpha^6$ and $m\alpha^6(m/M)$ for HD$^+$ rovibrational transitions beyond Born-Oppenheimer approximation
Zhen-Xiang Zhong, Ping Yang, Vladimir I. Korobov et al. (+2 more)
The effective
Hamiltonian of $m\alpha^6$ and $m\alpha^6(m/M)$ order corrections for hydrogen molecular ions has been derived in [ Z.-X. Zhong, et al., Phys. Rev. A {\bf98}, 032502(2018).], in this work we express the energy correction in the form of finite-value effective operators. The cut-off regularization scheme is used to determine finite part of divergent operators of the leading-order
recoil corrections. Numerical calculations of first-order contributions are performed in the Hylleraas basis set. Combining the second-order terms calculated in recent work [V. I. Korobov, et al., Mol. Phys. e2563023 (2025).], the $m\alpha^6$-order corrections for the fundamental rovibrational transition are obtained with an uncertainty three times smaller than in previous calculations.
Read the full abstract ▾
All authors Zhen-Xiang Zhong, Ping Yang, Vladimir I. Korobov, Chun Li, Ting-Yun Shi
Optics
Explicit Construction of Floquet-Bloch States from Arbitrary Solution Bases of the Hill Equation
Gregory V Morozov
For the Hill equation describing one-dimensional periodic systems, a constructive formulation is developed for generating Floquet-Bloch states directly from arbitrary pairs of linearly independent solutions. One-dimensional photonic
crystals are used as a concrete illustration. Explicit closed-form formulas map an arbitrary fundamental system to the corresponding Floquet-Bloch basis via the monodromy
matrix, including the generic Jordan band-edge case, without reliance on canonically normalized solutions. The construction can be expressed directly in terms of the transfer
matrix, making the residual representation freedom transparent and providing an implementation-ready framework for analytical and numerical studies of periodic systems.
Read the full abstract ▾