Near-zero-field magnetometers, particularly the spin-exchange relaxation-free (SERF) magnetometer, despite their exceptional sensitivity, face a fundamental limitation: their accuracy is inherently tied to the precision of precalibrated magnetic coils, creating a circular dependency in calibration. To break this loop, we establish a comprehensive analytical framework to describe the full-sequence free-induction-decay (FID) trajectories of atomic ensembles in the near-zero magnetic field regime. By explicitly incorporating the dynamic evolution of the polarization-dependent slowing-down factor $q(P)$, our model provides a rigorous description of spin precession in ultraweak field environments, enabling the extraction of absolute field components without relying on external coil-based references. The mathematical integrity of the model is confirmed by excellent agreement with direct numerical simulations of the Bloch equations. We demonstrate that a single FID waveform can simultaneously resolve six independent physical parameters through a multiparameter nonlinear estimation process. Experimental results validate that the reconstructed magnetic fields exhibit high fidelity, with a coefficient of determination of approximately 0.99. Under current experimental conditions, this approach achieves a practical reconstruction uncertainty of 0.1 nT for the absolute magnetic field and 5 and $1{\mathrm{s}}^{-1}$ for pumping and relaxation rates, respectively. This work redefines the SERF magnetometer as a calibration-free magnetometer, providing a robust foundation for autonomous quantum sensing in remote or inaccessible environments.

Precise control over deformation behaviors is essential for shape-morphing devices, adaptive actuators, and soft robotics. However, designing materials to achieve the whole user-defined deformation pathway remains a significant challenge. This work introduces a fast, physics-informed approach, namely incremental contrastive learning, for the inverse design of Willis lattice metamaterials capable of achieving desired deformation pathways under prescribed external constraints. We first implement gauge transformation to analytically derive an initial Willis lattice configuration and then leverage contrastive learning to develop a local learning rule on each incremental deformation step so as to design strain-dependent Willis parameters to realize the desired deformation pathway. Numerical simulations are performed to validate the approach and demonstrate its ability to program diverse and complex target deformations prescribed on boundary nodes, internal nodes, or even all nodes. Notably, we demonstrate independent control over both the final deformed shape and the specific pathway taken to achieve it, such as programming “early” versus “delayed” convexity to reach an identical final configuration. The developed framework provides a robust and efficient solution for programming matter, opening new avenues for designing complex morphing structures and tunable systems.

Magnetic anisotropy is a fundamental prerequisite for stabilizing long-range order in two-dimensional (2D) magnets, yet its evaluation via first-principles methods is computationally prohibitive for large-scale material discovery. Here, an octahedral-field-informed machine learning framework is reported, specifically designed to identify 2D magnets with perpendicular magnetic anisotropy (PMA). By incorporating crystal-field-informed descriptors, this model transcends traditional composition-based heuristics, achieving an 89% classification accuracy while accelerating the discovery process by 6 orders of magnitude. High-throughput screening of over 10 000 candidates reveals 15 novel PMA materials, with ${\text{Ba}}_2{\text{VTe}}_2{\mathrm{S}}_2$ identified as a prominent candidate. Specifically, axial elongation along the out-of-plane direction by Ba cations modulates the $d$-orbital splitting, resulting in a giant magnetic anisotropy energy of 5.65 meV per V atom. This work provides an interpretable framework for rapid discovery of 2D PMA magnets and highlights how physics-informed descriptors enable rational design of low-dimensional magnetic materials.

This paper presents a technology for fabricating microstructures based on carbon nanowalls (CNWs) integrated on silicon nitride (${\text{SiN}}_{\mathrm{x}}$) waveguides. The step-by-step fabrication process is described, including chemical mechanical planarization, deposition of molybdenum contacts, selective etching of the upper ${\mathrm{SiO}}_{\mathrm{x}}$ buffer layer relative to ${\text{SiN}}_{\mathrm{x}}$, and plasma-enhanced chemical vapor deposition of CNWs. The photothermoelectric response of the structures was studied in the C-band, near the $1.55\mathrm{\mu }\mathrm{m}$ wavelength. The results demonstrate that the primary mechanism of the response to the laser emission is the Seebeck effect, providing a maximum sensitivity of $0.037\mathrm{V}/\mathrm{W}$ without thermal degradation of the CNWs. Furthermore, the amplitude-frequency response of the structures corresponds to that of a fourth-order Butterworth filter with a cutoff frequency of 13.4 kHz. The utilization of the Joule-heating-assisted enhancement allows for a 21.4-fold increase in the output signal amplitude, but it also reduces the bandwidth. These findings highlight the prospects for CNWs in integrated photonics for near-infrared emission detection.

We propose a time- and wavelength-multiplexed remote atom-atom entanglement generation protocol based on cavity-assisted photon scattering (CAPS). This is designed to achieve a high rate and high fidelity with robustness to operational imperfections, parameter fluctuations, and auxiliary time costs, such as percent-level photon impurity, timing and cavity parameter jitter, and atom shuttling time costs. We benchmark this protocol using comprehensive analytical and numerical modeling of the atom-cavity dynamics, including state-dependent pulse-delay effects, photon temporal impurity, atom-cavity system parameter fluctuations, and crosstalk among atoms through a shared cavity mode. With realistic atom-cavity system performance, we predict $2\times {10}^5{\mathrm{s}}^{-1}$ successful atom-atom Bell pair generation even without in-cavity qubit reset, substantially enhanced from two-photon-interference-based protocols, at a predicted heralded fidelity of 0.999. We further show that the predicted rate scales further by the use of wavelength multiplexing while maintaining the fidelity.

Free-space optical communication based on photonic orbital angular momentum (OAM), including OAM multiplexing and OAM modulation schemes, has the potential to greatly increase information transfer capacity. However, the presence of atmospheric turbulence can severely distort the spatial modes of OAM beams, resulting in modal scattering and distortions. In this study, we theoretically develop a method to control the total OAM of a superimposed OAM beam (total OAM in a superposition state but not the OAM eigenstate in general)—coherent superposition of $N$ OAM eigenstates—propagating through the time-varying atmospheric turbulence by dynamically modulating the complex coefficient of each OAM eigenstate and experimentally demonstrate the total OAM control strategy. Our experimental results show that the control error of total average OAM per photon is around $0.1\hslash$ in a turbulent channel with a scintillation index of 1.03, and the control strategy is effective even in nonunitary turbulent systems. Furthermore, we successfully receive a data packet using two-OAM-eigenstate-superposition beams for two bits per pulse in unitary and nonunitary turbulent channels. Our study offers an effective way to control the OAM of light beams propagating in turbulent media, which will find potential applications in free-space optical communication and remote sensing.

Diffusion is a prominent source of noise affecting nuclear magnetic resonance at the nanometer scale (nano-NMR), preventing high-resolution studies of unpolarized liquid samples and hindering the development of nanofluid devices. Actively managing diffusion noise through sample confinement is likely to unveil alternative noise sources that have so far been disregarded, as they occur in longer timescales and consequently are masked by diffusion. These secondary noise sources could diminish the advantages provided by sample confinement, but they may also yield valuable information about the behavior of the fluid sample and its interactions with the confinement device. In this article, we study in detail two previously unaccounted noise models for confined nano-NMR, namely, surface interactions and porosity, and discuss their implications for typical nano-NMR experiments.

Distributed quantum computing offers a scalable route to quantum information processing by entangling spatially separated processors. Although gate teleportation enables universal computation across distributed nodes, it requires repeated consumption of high-fidelity Bell pairs, ancillary qubits, and real-time feedforward, which imposes significant overhead and reduces fidelity. However, many variational quantum algorithms do not demand full universality; rather, they rely on sufficient expressibility to explore solution spaces effectively. Building on this, we propose a distributed variational quantum computing protocol based on deterministic entanglement tuning. In contrast to probabilistic filtering, our approach deterministically modulates preshared entanglement using only local operations and classical communication. We validate the protocol through a proof-of-principle experiment by estimating ground-state energies of the $\text{He}\text{−}{\mathrm{H}}^{+}$ molecule and the Schwinger model, showing that diverse entanglement levels can be engineered to match problem-specific requirements. Our results suggest a practical alternative for near-term distributed quantum applications.

The quantum dynamics of quasiperiodic systems display a rich variety of physical behaviors due to the combination of rotational symmetry that is mathematically forbidden in periodic systems, and long-range order despite the lack of translation symmetry. New experimental probes into these dynamics with a quantum simulator, consisting of ultracold atoms in an optical lattice potential, will yield new insights into the physics of quasiperiodic systems. This potential is imbued with the flexibility, tunability, and purity of the individual laser beams that constitute it, allowing for exquisite control over a rich system. Programmable dynamic control over the lattice beam phases opens up an even richer space of achievable systems via Floquet engineering. We thus describe an experimental scheme for creating a programmable, dynamic, two-dimensional quasiperiodic optical lattice with heavily suppressed phase noise. We observe suppression of phase noise for frequency components up to 5 kHz, and report phase noise suppression of over 70 dB over the dc-60 Hz frequency band. We further demonstrate a phase modulation bandwidth of 350 kHz. This scheme allows for full translational and phasonic control of the lattice, including changes to the rotational symmetry of the potential, at speeds exceeding the lattice recoil velocity of lithium, which paves a path toward direct observation and control of quantum dynamics in quasicrystals.

Low-field nuclear magnetic resonance (NMR) spectroscopy ($<1\mathrm{T}$) often suffers from reduced sensitivity due to low nuclear spin polarization, magnetic field inhomogeneities, and poor chemical shift resolution, compared to high-field systems, and the low Larmor frequency at low field limits the achievable quality factor ($Q$) of NMR detection circuits. These factors may result in poor detection fidelity and broad spectral linewidths that obscure details about the chemical environment being analyzed. Radiofrequency amplification by stimulated emission of radiation (RASER) is a radiation damping feedback mechanism between a strongly coupled nuclear spin system and a high-$Q$ resonator, which may yield linewidths orders of magnitude narrower than is achievable using conventional acquisition protocols at low magnetic field strengths. Here, we present a simple theoretical description of RASER and practical implementation details for a high-$Q$ resonator. We demonstrate a repeatable acquisition protocol for hyperpolarized ${}^{129}\mathrm{Xe}$ gas RASER at 1.7 mT, achieving sufficiently narrow linewidths to resolve the chemical shift separation between ${}^{129}\mathrm{Xe}$ gas phase and dissolved phase.

Mode interactions in crystalline microresonators play a significant role in determining the behavior and characterization of optical resonances, particularly in the presence of multiple wavelengths or polarization-dependent effects. In this study, we investigate the behavior and error signal response of oppositely polarized modes near mode crossings in a ${\text{MgF}}_2$ whispering-gallery-mode resonator, in the look for nonlinearities that can be used as performance enhancers. Our analysis reveals a pronounced enhancement in the sensitivity of the transverse-electric mode when the crossing modes are closely coupled, compared to when they are further apart. This effect is attributed to the modified energy exchange dynamics and polarization conversion occurring at the crossing point. By characterizing these interactions, we provide new insights into mode hybridization and the underlying physical mechanisms governing mode splitting and detuning in crystalline microresonators. These findings have implications for precision sensing applications and the optimization of resonator-based optical systems.

We optimize theoretically and experimentally the performances of the recently demonstrated modulation transfer protocol [D.-A. Trinh et al., Modulation transfer protocol for Rydberg rf receivers, Appl. Phys. Lett. 125, 154001 (2024)] aiming at extending the bandwidth of quantum rf receivers based on hot Rydberg atoms. This optimization relies on tuning the parameters of the phase modulation of the coupling beam, which is converted by the nonlinear response of the atoms into an amplitude modulation of the probe beam. We develop a theoretical model to optimize both the modulation frequency and the modulation amplitude of the coupling beam, thereby maximizing the atomic response. Once optimized, the sensitivity to detuned rf fields of this modulation transfer protocol is measured and compared with that of the conventional protocol. This comparison shows that the new protocol permits a strong increase in the detection bandwidth. Indeed, it outperforms the usual one as soon as the rf signal to be measured is detuned by more than a few MHz. We illustrate the capability of this modulation transfer protocol to enhance the detection bandwidth by showing experimentally how it permits bridging the gap between two Rydberg transitions separated by 166 MHz. In all cases, the experimental results are in good agreement with the simulations.

A dynamically tunable Fano resonance sensor based on PIN-diode-reconfigurable resonators is proposed to achieve multistate frequency tuning while maintaining high sensitivity in a microwave spoof surface plasmon polariton (SSPP) platform. The sensor comprises a fishbone-shaped resonator coupled with a corrugated annular resonator, providing a broadband continuum state and a narrowband discrete state, respectively. A high-$Q$ Fano resonance is excited through their coherent interference. Two PIN diodes are integrated on both sides of the annular resonator, and controllable structural symmetry breaking is introduced via horizontal offset of the ring structure, enabling multistate electrically controlled tuning of the resonant frequency. Experimental results show that by switching among four diode bias configurations (both forward, left-forward and right-reverse, left-reverse and right-forward, and both reverse), four-level dynamic frequency regulation is achieved within the range of 1.15–1.43 GHz. In concentration detection of ethanol and sucrose solutions, the sensor exhibits pronounced dielectric response, with a maximum sensitivity of 169.4 MHz/r.i.u. (refractive index unit). This work provides an effective implementation approach for constructing microwave dielectric sensors that combine high sensitivity with reconfigurability, offering strong potential for adaptive sensing applications.

Recently, the $M{A}_2{Z}_4$ family has become a key focus in condensed matter physics and materials science due to its unique structure and tunable electronic properties. This study systematically investigates the crystal structure, electronic structure, magnetism, mechanical properties, and the potential applications of the ${\mathrm{VN}}_2{\mathrm{B}}_2{\mathrm{S}}_2$ monolayer in spintronics and optoelectronics. Using first-principles calculations, we analyze key properties of this material, including its stability, magnetic anisotropy, and carrier mobility. The computational results indicate that the ${\mathrm{VN}}_2{\mathrm{B}}_2{\mathrm{S}}_2$ monolayer exhibits excellent structural stability, magnetic anisotropy, and outstanding electronic transport characteristics, particularly highlighting its potential for spin-dependent electronic devices. Further investigations reveal that the ${\mathrm{VN}}_2{\mathrm{B}}_2{\mathrm{S}}_2$ monolayer exhibits pronounced spin-polarized transport properties and excellent photoelectric responses in pn-junctions, pin-junction field-effect transistors, and pin-junction phototransistor structures, demonstrating its broad application prospects in spintronic and optoelectronic devices.

We report a distributed-feedback behavior in electron-driven dielectric gratings, arising from intrinsic forward-backward wave interactions, relevant to low-threshold coherent emission. Coupled-mode analysis reveals a quasi-stable region in the groove-depth dependence of the distributed-feedback coupling, consistently beginning at a fundamental organ-pipelike resonance. When driven by an electron beam, the guided power exhibits a corresponding resonance landscape, with a peak at the fundamental organ-pipelike resonance followed by regrowth in the quasi-stable region, highlighting a strong correlation between the intrinsic distributed-feedback behavior and electron-surface mode interaction. Based on this framework, we numerically demonstrate a silicon-grating chip-scale distributed-feedback Cherenkov free-electron laser operating in the terahertz (THz) regime and employing a micrometer-scale grating with an optimized groove depth. Small-signal and coupled-mode analyses for the optimized structure predict a milliampere-level oscillation threshold in good agreement with particle-in-cell simulations, while time-domain simulations confirm Bragg-resonant field buildup at 0.328 THz via electron microbunching with sustained guided-field growth along the grating. These results establish a general design principle for low-threshold terahertz sources based on distributed-feedback surface-mode resonances.

Spin qubits in semiconducting quantum dots are currently limited by slow readout processes, which are orders of magnitude slower than gate operations. In contrast, Andreev spin qubits benefit from fast measurement schemes enabled by the large resonator couplings of superconducting qubits but suffer from reduced coherence during qubit operations. Here, we propose fast and high-fidelity measurement protocols based on an electrically tunable coupling between quantum dot and Andreev spin qubits. In realistic devices, this coupling can be made sufficiently strong to enable high-fidelity readout well below microseconds, potentially enabling mid-circuit measurements. Crucially, the electrical tunability of our coupler permits to switch it off during idle periods, minimizing crosstalk and measurement back-action. Our approach is fully compatible with germanium-based devices and paves the way for scalable quantum computing architectures by leveraging the advantages of heterogeneous qubit implementations.

Plasmonic nanobubbles are extensively employed in many fields owing to their distinctive optical and photothermal properties. The mechanisms behind nanobubble formation have attracted growing attention. This work proposes a model combined with the Lattice Boltzmann method and multilayer Mie theory to observe the transient optical and photothermal behaviors during nanobubble formation. The thermoplasmonic effect of gold nanoparticles reduces the density of the surrounding water, generating a spatiotemporally varying refractive index field. In this condition, it is found that for nanoparticles with a 60 nm diameter, the decline in absorption cross section during nanobubble growth leads to prolonged nucleation time. Moreover, the influence of the electric field force acting on water molecules within the plasmonic near-field on nanobubble growth dynamics is investigated. The anisotropic growth of nanobubbles in plasmonic-enhanced nonuniform local electric fields is revealed. Subsequently, rational regulation strategies are designed, including ${\mathrm{SiO}}_2$ coating of nanoparticles and adjustment of incident light polarization modes, which enable precise control of the dimensional anisotropy of nanobubble thickness while maintaining the particle structural integrity. Our work provides a feasible approach for the precise regulation of nanobubble growth and mechanical effects.