A cold-atom gravimeter, with high sensitivity, long-term stability, and absence of mechanical wear, provides an unprecedented technical means for geology, resource exploration, and the establishment of a high-resolution marine geoid. However, present atom gravimeters still face severe challenges from broadband and large-amplitude vibrations caused by waves and engines in the dynamic marine environment. Conventionally, vibration compensation is employed to address such issues, but it is insufficient for accelerations with amplitudes reaching up to $1\mathrm{m}/{\mathrm{s}}^2$ during navigation. Variations in the probe velocity can lead to large detuning of the Raman laser and thus introduce additional phase shifts. To address this problem, we proposed a postcorrection method, Raman detuning compensation, built upon the existing vibration compensation, and validated its effectiveness aboard a commercial cargo ship, where the data noise can be reduced to 45% of the previous value after compensation during the voyage. This scheme is expected to overcome the limitations of existing vibration compensation methods and advance cold-atom gravimeters toward practical vehicular, marine, and aviation applications.

Pressure metrology in cryogenic ultrahigh vacuum is limited by the need for in situ readout that does not perturb the cold environment. We propose a passive gauge based on the vertical translational mode of a ferromagnetic sphere levitated above a superconducting surface by the Meissner effect. In the molecular-flow regime, gas-surface momentum exchange adds a damping rate ${\gamma }_{\mathrm{gas}}\propto P$, so the pressure can be inferred from mechanical ring-down. Using Fisher-information analysis, we derive Cramér–Rao lower bounds for estimating the total damping rate and propagate them to an analytic pressure uncertainty that includes pressure-independent losses from residual dissipation and eddy currents. The resulting scalings with sphere radius $R$ reveal an optimum: larger $R$ improves low-$P$ sensitivity but increases intrinsic damping and narrows the molecular-flow range. For $T_{\mathrm{env}}=4.2\mathrm{K}$ and intrinsic damping ${\gamma }_0={10}^{-6}{\mathrm{s}}^{-1}$, we find $R_{\mathrm{opt}}\approx 2.4\mathrm{mm}$ and a resolution floor $\delta P_{\text{mea}}\approx 4\times {10}^{-10}\mathrm{Pa}$ at a signal-to-noise ratio of 1, with a molecular-flow upper limit of ${10}^{-2}–{10}^{-1}\mathrm{Pa}$ set by gas species and the Knudsen criterion. These results provide sizing and integration-time guidelines for levitated mechanical cryogenic vacuum gauges.

A broadband electromagnetic source is important for scientific and technological applications. Quantum vacuum fluctuations, which manifest most prominently in the Casimir effect, provide a fundamentally broadband electromagnetic source. Here, we explore a potential consequence of the broadband nature of quantum vacuum fluctuations, by showing that such fluctuations can enable measurement of material permittivity over a broad frequency range. Specifically, we consider the Casimir force in a parallel-plate geometry, with one plate covered by a nanoscopic thin film. Using a machine learning approach, we show that one can infer both the thickness of the film and its permittivity over a broad frequency range, starting from the dependency of the Casimir forces on the spacing between the two plates. Our work highlights the application potential of using vacuum fluctuations as a naturally existing broadband electromagnetic source for material characterization and shows that the inverse problem in Casimir force calculation can be solved with machine learning.

The imprint effect, a major reliability issue in ferroelectric memories, degrades the device by shifting the coercive field over time. This work reviews existing imprint models and introduces a phase-field model for polycrystalline thin films. The model identifies grain-boundary charge screening (GBCS) as a key bulk imprint mechanism. It demonstrates that the depolarization field near grain boundaries attracts trapped charges, which in turn suppress domain nucleation for reverse polarization switching. Furthermore, the model reveals that domain wall motion is essential for the GBCS mechanism to induce imprint in a thin film and can explain the widened hysteresis loop observed in experiments. These findings provide new insights into imprint physics and advance strategies for improving ferroelectric memory reliability.

Interfacial engineering of spin currents is crucial for developing spintronic and memory devices. Here, we demonstrate the nonreciprocal transport of spin currents in Pt/Ti and Ti/Pt bilayers adjacent to a Py ferromagnetic layer using spin pumping and spin-torque ferromagnetic resonance (ST-FMR) techniques. Systematic thickness-dependent measurements reveal that the magnetic damping, which reflects the efficiency of spin-current injection, depends strongly on the stacking order. In Py/Pt/Ti structures, the magnetic damping increases with Pt thickness and saturates, following the conventional spin-diffusion model. In contrast, Py/Ti/Pt structures exhibit a rapid decline and saturate at thicker Ti thicknesses. The reduction of damping in the Py/Ti/Pt structures upon adding the Pt layer indicates strong orbital pumping and spin backflow at the Ti/Pt interface. Furthermore, ST-FMR measurements show opposite signs and distinct magnitudes of the spin-orbit torque efficiency for the two stacking configurations. These results confirm that the Pt layer dominates spin-current generation via the spin Hall effect, while the Ti layer contributes through the orbital Hall effect. Our results establish a clear asymmetry in spin-current propagation across Pt/Ti interfaces and provide a quantitative framework for understanding interfacial spin transport in multilayer spintronic systems.

Fast and robust entanglement generation is a central requirement for scalable quantum technologies, where limited coherence time, parameter drift, and timing uncertainty can otherwise erase quantum advantage. We investigate entanglement generation in topological open quantum systems governed by an effective non-Hermitian Hamiltonian. For a lossy two-qubit dimer with asymmetric dissipation, tuning the coherent coupling across an exceptional point (EP) produces a PT-like crossover between decay-rate splitting and frequency splitting, which directly reshapes the conditional (no-jump) concurrence dynamics in the single-excitation manifold. Embedding the dimer into a non-Hermitian Su-Schrieffer-Heeger (SSH)-like ladder yields multiple EPs through edge-bulk hybridization. Our key contribution is a practical design rule: among these EPs, the operational one for entanglement is the “edge-mode EP,” defined by the EP whose coalesced eigenvector is maximally localized on the target edge pair; the near-optimal working point lies slightly above this EP, balancing preparation speed, no-jump success probability, timing-jitter tolerance, and robustness to bulk detuning disorder. Using thresholded operational metrics (preparation time, success probability, rate, jitter window, and disorder sensitivity), we map these trade-offs and show that topology-assisted confinement plus EP-enabled mode selection enables fast and robust heralded edge entanglement.

Bioinspired neuromorphic spiking sensors hold great promise for energy-efficient and architecturally simplified neuromorphic networks. Here, an energy-efficient artificial spiking sensor based on a patterned polycrystalline vanadium dioxide (${\text{VO}}_2$) memristor grown by direct-current (dc) reactive magnetron sputtering was developed to achieve high sensitivity and low-energy consumption simultaneously. The memristor demonstrates high endurance in both static and dynamic electrical measurements with low cycle-to-cycle variations and excellent spiking performance when integrated into a 1R (memristor)-1T (transistor) spiking circuit. By optimizing the memristor current and output capacitor, the circuit achieves tunable output frequencies of 181–784 kHz under a 5-V supply voltage and an estimated intrinsic capacitance of approximately 0.51 nF. In-sensor temperature encoding is also achieved under a memristor current of 0.1478 mA without an additional external capacitor, exhibiting an excellent sensitivity of $2.98–13.62\mathrm{kHz}/°\mathrm{C}$, a low total energy consumption of 2.73–5.63 nJ/spike and a signal-to-noise and distortion ratio (SNDR) of 30.95–41.21 dB from 30 to $50°\mathrm{C}$, as well as a high resolution of $0.18°\mathrm{C}$ at $47.5°\mathrm{C}$. Compared with conventional CMOS readout integrated circuits, the energy consumption can be further reduced by lowering the supply voltage and minimizing the intrinsic capacitance through full circuit integration, while the SNDR can be enhanced by mitigating the stochasticity of ${\text{VO}}_2$ and reducing circuit noise, which will require further optimizations of material characteristics and device geometry.

Large language models have dominated the scientific and media landscape due to their impressive performance in processing large amounts of data and producing humanlike text. Nevertheless, their high energy demand and slow processing remain bottlenecks to further improving model quality while making the models broadly accessible. To address these bottlenecks, we investigate how reservoir computing performs in natural language processing, which could enable fast and energy-efficient hardware implementations. Studies investigating the use of reservoir computing as a language model remain sparse. In this paper, we compare three distinct approaches to character-level language modeling: two reservoir-computing approaches, in which only an output layer is trainable, and a well-known transformer-based architecture, which learns a fully trainable attention-based sequence representation. We explore the performance, computational cost, and prediction accuracy of both paradigms while varying the number of trainable parameters consistently across all models. Using a consistent pipeline for all three approaches, we demonstrate that transformers excel in prediction quality, whereas reservoir computers remain highly efficient, substantially reducing training and inference times. Furthermore, we investigate two types of reservoir computing: a traditional reservoir with a static linear readout and an attention-enhanced reservoir that dynamically adapts its output weights through an attention mechanism. Our findings illustrate how these paradigms scale and provide guidelines for balancing resource constraints with performance.

We present a comprehensive theory of electromagnetic modes in spherical cavities, resolving questions about the nature of angular quantization. The standard result that angular indices ($\ell ,m$) must be integers is shown to be a consequence of domain constraints—regularity at both poles and single valuedness in the azimuthal coordinate—rather than a requirement imposed by Maxwell’s equations themselves. We demonstrate that, for the sectoral case $\nu =m$, the function ${\sin }^m\theta$ exactly solves the angular eigenvalue equation for any real $m>0$, giving rise to a continuous dispersion curve. We demonstrate why nonsectoral modes (tesseral and zonal) appear only at isolated integer points on the full sphere and show how boundary modifications such as cones and wedges convert these isolated points into continuous families of modes. Complete field solutions, wave impedances, and energy integrability conditions are derived. At the limiting point $(\nu ,m)=(0,0)$, the electromagnetic field vanishes identically while the underlying Debye potential remains nontrivial—a distinction with implications for mode counting that connects to longstanding questions in gauge theory and cavity quantization. Full-wave simulations validate the theoretical predictions with sub-percent accuracy. These results raise the possibility of structural analogs in wave equations on curved spacetimes, where conical deficits or horizon excisions similarly modify the angular domain.

In our previous work, we have theoretically shown that the temporal interface in a wire medium may result in an unambiguous encoding of the spatial frequencies of the initial wave package propagating along the wires into temporal frequencies of a created pulse propagating obliquely to them. This effect of encoding information on subwavelength spatial field distributions into frequency spectra of propagating waves opens a new door for far-field subwavelength imaging. Earlier, we suggested achieving the needed temporal interface with microplasma discharges. In the present paper, we show analytically and numerically that the same effect may be offered in a simpler and more practical way—by switching PIN diodes loading the wires. Since the temporal interface in this case occurs between two media with strong spatial dispersion, besides the wave packet responsible for the imaging a parasitic one is generated. However, the frequency range of this second wave packet is so different that it cannot spoil the image retrieval.

Perovskite solar cells (PSCs) have rapidly advanced over the past decade, reaching certified efficiencies above 27%, and are now regarded as promising candidates for next-generation photovoltaics. Among the emerging device architectures, quasi-interdigitated back-contact PSCs (QIBC PSCs) eliminate the transparent conductive oxide (TCO) layer and collect charges through patterned rear electrodes, enabling reduced parasitic absorption, improved photocurrent generation, and compatibility with flexible and tandem devices. Despite these advantages, optical losses—particularly front-surface reflection—remain a significant challenge, making antireflective coatings (ARCs) essential for further efficiency enhancement. Different ARCs’ geometries offer a pathway to broadband, omnidirectional light coupling beyond the limits of conventional planar coatings. In this work, we employ numerical simulations to systematically investigate the effect of ARC geometries in QIBC PSCs. We compare planar, double-layer, ball, pyramidal, and dome-like structures in terms of absorption-reflection-transmission spectra, generation rate distribution, and current-voltage characteristics. Our results show that dome-like ARCs provide superior optical and photovoltaic performance, increasing the power conversion efficiency (PCE) from 20.66% (no ARC) to 24.38%, while the addition of a back-side mirror further enhances efficiency to 24.72%. These findings highlight geometry-driven ARCs as a powerful strategy for advancing QIBC PSCs toward their theoretical efficiency limits.

Superconducting quantum interference devices (SQUIDs) are state-of-the-art in ultrasensitive magnetometry; however, conventional SQUIDs are fundamentally limited by the inherently nonlinear, periodic nature of their transfer function. Although flux-locked loop configurations can mitigate this issue, they introduce electronic complexity and bandwidth constraints that hinder scalability in quantum circuits. In this work, we present an experimental demonstration of the bi-SQUIPT, a flux transducer that modulates the density of states in a proximitized superconducting weak link. The device employs a dual-loop architecture with differential readout, which enables cancellation of nonlinearities typical of individual elements, achieving a voltage swing of approximately $120\mathrm{\mu }\mathrm{V}$. Measurements yield a spurious-free dynamic range of up to 60 dB, consistent with theoretical predictions and comparable to that of SQUID arrays, while maintaining femtowatt power dissipation. The results further highlight a remarkable operational stability up to 600 mK, positioning the bi-SQUIPT as an enabling technology for high-density cryogenic quantum electronics.

Photonic quantum computing is a strong contender in the race to fault tolerance. Recent proposals using qubits encoded in frequency modes promise a large reduction in hardware footprint and have garnered much attention. In this encoding, linear optics, i.e., beam splitters and phase shifters, is necessarily not energy conserving and is costly to implement. In this work, we present designs of frequency-mode beam splitters based on modulated arrays of coupled resonators. We develop a methodology to construct their effective transfer matrices based on the SLH formalism for quantum input-output networks. Our methodology is flexible and highly composable, allowing us to define $N$ mode beam splitters either natively based on arrays of $N$-resonators of arbitrary connectivity or as networks of interconnected $l$ mode beam splitters with $l<N$. We apply our methodology to analyze a two-resonator device, a frequency-domain phase shifter, and a Mach-Zehnder interferometer obtained from composing these devices, a four-resonator device, and derive a no-go theorem forbidding the native implementation of a subclass of $N$ mode frequency-domain beam splitters with arrays of $N$-resonators.

Angle gratings can efficiently extract light trapped in high-order-topological-charge whispering-gallery modes of microring resonators into free-space beams, yet backscattering remains the key factor compromising the purity of the emitted topological charge. In this study, we develop a coupled-mode theory for defect scattering in passive microring cavities. Using a non-Hermitian Hamiltonian framework, we describe the defect-induced asymmetric coupling between clockwise and counterclockwise modes. This defect-induced asymmetry drives the evolution from standing-wave modes to unidirectional traveling-wave modes, ultimately enabling the generation of high-purity vortex light emission. Rotating a single grating tooth defect by $0–2\pi$ in a rotationally symmetric microring periodically modulates intracavity backscattering and mode coupling. When weak backscattering is fully suppressed by destructive interference, the intracavity standing wave decouples and reconstructs into a unidirectional traveling wave, emitting a one-handed vortex beam. Even weak defect-induced backscattering degrades traveling-wave purity. Introducing a second independent grating tooth defect moving along the inner wall enables periodic coherent cancellation, restoring the traveling-wave state with vortex emission purity up to 99%. These theoretical predictions agree well with simulations. Of note, this study reveals the evolution of microcavity eigenvalues and eigenstates with defect position. First, when backscattering is canceled out, the real parts of the eigenvalue spectrum exhibit contact and separation behavior at degenerate frequencies, while the imaginary parts cross linearly, describing the merging of split eigenvalues back to a degenerate state by suppressing of mode coupling. Second, eigenstate phase rigidity remains well above zero, demonstrating that eigenvectors maintain linear independence without coalescing. This distinguishes the coherent cancellation process from non-Hermitian exceptional points. Additionally, the electric-field overlap integral approaches unity, indicating perfect spatial reconstruction of the standing wave into the original unidirectional traveling wave. This study provides a theoretical basis for defect engineering and non-Hermitian photonic devices. In addition, the high-purity vortex will have broad application prospects in on-chip information processing and particle micromanipulation.

The atomic magnetometer exhibits high sensitivity in weak magnetic field detection, with diverse applications in dark matter detection, biomagnetic sensing, wireless communication, etc. However, its performance, especially in environmental robustness and sensitivity, is largely limited by laser characteristics. Here, we realized two potassium Faraday lasers operating at potassium D1 (770 nm) and D2 (767 nm) lines, serving as pump and probe lasers for a potassium atomic magnetometer. Utilizing the Faraday anomalous dispersive effect for frequency selection, the lasers achieve automatic wavelength locking within the atomic Doppler broadening, enabling robust, self-stabilizing operation without tedious adjustments. Furthermore, both lasers exhibit strong immunity to environmental disturbances, such as vibration and temperature variations. By implementing the modulation transfer spectroscopy (MTS) technique, the frequency stability of the pump laser and probe laser reaches approximately $5.1\times {10}^{-13}/\sqrt{\tau }$ and $6.2\times {10}^{-13}/\sqrt{\tau }$, respectively. Notably, the optimized frequency stability is accompanied by better power stability, showing threefold and fivefold improvements over their free-running counterparts, which reaches the ${10}^{-5}$ level at 1 s. The enhancements in laser performance directly improved the magnetometer’s performance, yielding a magnetic noise floor of approximately $100\mathrm{fT}/\sqrt{\mathrm{Hz}}$ at 10 Hz under a bias field of 1000 nT. Therefore, with hands-off operation, environmental robustness and competitive sensitivity, this achievement holds promising prospects for both laboratory and field-deployable applications.

We present a comprehensive study of quantum dot (QD) coupling to various phononic modes in a phononic waveguide (WG), combining multiband $\mathit{k}·\mathit{p}$ and configuration-interaction (CI) QD state simulations with finite-element WG mode modeling. We consider self-assembled Stranski-Krastanov InGaAs/GaAs as well as local droplet-etched GaAs/AlGaAs structures. Using $\mathit{k}·\mathit{p}$-CI calculations, we quantify the strain and piezoelectric responses of InAs and GaAs QDs. By systematically isolating volumetric/shear deformation-potential and piezoelectric channels, we demonstrate how mode symmetries dictate distinct coupling mechanisms. We identify the dominant coupling channels and characterize their observable signatures in the QD response. We predict strong linear energy shifts under volumetric strain and quadratic behavior under shear strain, especially in GaAs QDs. The piezoelectric effect is dominated by polarizability, which also leads to a quadratic response. The simulations show energy modulations up to 0.7 meV for an acoustic wave with 0.1 nm amplitude. The quadratic response to shear strain and piezoelectric field leads to frequency doubling in the QD response to a mechanical wave and to nonharmonic time traces when linear and quadratic effects contribute to a similar degree. The deep understanding of QD-acoustic couplings opens pathways to the optimal design of QD and WG structures, as well as to improved engineering of acousto-optic quantum interfaces.