To exploit the subnanometer dimensions of qubits for large-scale quantum information processing, corresponding control architectures require both energy and space efficiency, with the on-chip footprint of unit-cell electronics ideally being micrometer scale; however, the spin coherence of qubits in close packing is severely deteriorated by microwave crosstalk from neighboring control sites. Here, we present a crosstalk-mitigation scheme using foundry microelectronics to address solid-state spins at sub-100-$\text{μ}\mathrm{m}$ spacing without the need for qubit detuning. Using nitrogen-vacancy centers in nanodiamonds as qubit prototypes, we first demonstrate 10-MHz Rabi oscillations at milliwatt-level microwave power. By implementing active cancellation, we then demonstrate that the crosstalk field from neighboring lattice sites can be reduced to undetectable levels. We finally extend the scheme to show increased qubit control, or, effectively, enhanced spin coherence under crosstalk mitigation. Compatible with integrated optics, our results present a step toward scalable control across quantum platforms using silicon microelectronics.

Graphene is a promising material for nonlinear THz applications due to its high third-order susceptibility and tunable optical properties. Its strong nonlinear response, driven by free-carrier thermodynamics, facilitates efficient third-harmonic generation (THG), which can be further enhanced using resonant metasurfaces and plasmonic structures. In this study, we use a platform designed to boost THG at THz frequencies by integrating graphene ribbons into the interface between topological photonic crystals. To accurately capture the temperature dependence of the nonlinear optical response, we perform coupled simulations to model graphene’s optical and thermodynamic responses under THz photoexcitation, incorporating photoinduced hot-carrier effects within a multiphysics computational framework. This approach unveils the influence of carrier heating on THG, providing a more accurate description of nonlinear THz processes and revealing previously overlooked mechanisms of third-order conductivity modulation. We show that the elevated carrier temperature promotes high conversion efficiencies at moderate input intensities, within a design that operates in both reflection and transmission modes for advanced ultrafast optoelectronic devices in the THz regime.

Phononic frequency combs, a series of equidistant spectral lines generated using micro-electromechanical and nano-electromechanical systems, have promising potential for improving the performance of sensing applications. In this work, we introduce and thoroughly analyze a temperature sensing approach using phononic frequency combs, where the temperature is tracked by the spacing between adjacent comb fingers in lieu of the traditional single resonance mode tracking. Here, we demonstrate phononic frequency comb generation using 1:2 internal resonance between two coupled circular membrane modes (0,1) and (2,1) on an aluminum scandium nitride resonator. We systematically study the tuning mechanisms of phononic frequency comb spacing subject to drive conditions and temperature perturbations within the entire detuning range. Our findings, backed up with an analytical model, show a controllable method to engineer the temperature sensitivity of comb spacing. The demonstrated tracking technique, coupled with narrowband electrical filtering, opens avenues for signal processing applications requiring highly controllable thermal sensitivity.

Natural slender structures, such as plant leaves and petals, exhibit complex three-dimensional (3D) morphologies—including twisting, helical coiling, and saddle bending—driven by differential growth. The resulting internal stresses are partially relieved through the development of intrinsic curvature and torsion. The fundamental challenge lies in effectively correlating microscopic growth fields to the macroscopic shapes and mechanical responses of the ribbon structures. However, existing ribbon or shell models struggle to directly link growth gradients to macroscopic curvature and torsion, necessitating a reduced-dimensional framework. This work establishes a unified one-dimensional morphoelastic ribbon model derived asymptotically from 3D finite elasticity theory via a rigorous dimension reduction framework. The reduced-order model captures growth-induced nonlinear strains and finite rotations asymptotically. We obtain analytical solutions for saddle-bending and twisting configurations induced by specific growth gradients. Furthermore, numerical continuation traces the postbuckling evolution into helical morphologies. This framework explicitly links growth fields to ribbon curvature and torsion, providing fundamental mechanics insights into the morphogenesis of slender plant organs and offering potential for bioinspired soft robotics design.

Ultracold atoms coupled to optical cavities offer a powerful platform for studying strongly correlated many-body physics. Here, we propose an experimental scheme for creating diatomic molecules via cavity-enhanced photoassociation from an atomic condensate. The resulting system features long-range three-body interactions mediated by tripartite cavity-atom-molecule coupling. Beyond a critical pump strength, a self-organized square lattice phase for molecular condensate emerges, resulting in hybrid atom-molecule superradiance with spontaneous $U(1)$ symmetry breaking. Distinct from previously reported ultracold bosonic (fermionic) atomic superradiance, our findings demonstrate bosonic enhancement with a cubic scaling of steady-state photon number with total atom number. Additionally, strong photon-matter entanglement serves as a sensitive probe of superradiant quantum phase transition and may enable the study of super-Heisenberg-limited metrology enhanced by cavity-mediated three-body interactions. Our findings advance the frontier of quantum superchemistry and nonequilibrium many-body dynamics in cavity-coupled quantum gases.

Quantum key distribution (QKD) can distribute secret keys between two parties over a long distance. In practical applications, the demand for multiplexing QKD and conventional data communication through wavelength-division multiplexing (WDM) in the same fiber is increasing. However, the in-band noise that is difficult to filter out through experimental methods has become a key factor limiting the performance of WDM-QKD systems. In this work, we establish a practical decoy-state WDM-QKD model with advantage distillation (AD). We theoretically investigate the enhancement of AD technology on WDM-QKD systems and experimentally verify it. When the classical launch power is fixed at 8.6 dBm, the transmission distance can be extended by 80.3 km. When the classical received power is fixed at $-27$ dBm, the tolerable classical launch power can be extended by 5.4 dBm. In the experiment, we obtained positive key rates at the optimal block lengths of 2 and 3, respectively. Our results demonstrate the enormous potential of AD in WDM-QKD applications, providing a way for reducing the impact of noise on practical WDM-QKD systems.

We report on the generation of a tunable buffer-gas mixture within microfabricated alkali-vapor cells. We show that the combination of low-permeation windows with sequential openings of laser-actuated break seals enables adjustment of a $\mathrm{He}$-$\mathrm{Ne}$ noble gas mixture, fully compatible with alkali-metal dispensers. The gas reservoirs and the main cell cavities are initially sealed at the wafer level under distinct helium and neon atmospheres, respectively. Within each cell, after $\mathrm{Cs}$ vapor is released from the dispenser, the break seals are successively actuated to incrementally increase the helium fraction in the buffer-gas mixture. This process shifts the atomic clock frequency inversion temperature toward higher values. As an illustration, one of the fabricated cells was operated at $95{}^{\circ }\mathrm{C}$ in a coherent population trapping clock, achieving a fractional frequency stability of $9\times {10}^{-11}$ at an integration time of 1 day. These results demonstrate the feasibility of precisely tuning buffer-gas compositions in microfabricated vapor cells and support the suitability of $\mathrm{He}$-$\mathrm{Ne}$ mixtures for miniature atomic clock applications.

Angle encoder (AE) errors in rotary tables are a dominant source of systematic uncertainty in precision gravitational experiments employing rotating torsion balances. Here, we present and validate an in situ calibration method that leverages the torsion balance itself as a high-sensitivity angular reference. The technique is demonstrated on an apparatus designed to search for exotic spin-dependent interactions. This proof-of-principle demonstration achieves a calibration accuracy at the nanoradian level. This accuracy is limited by statistical fluctuations and uncertainty in the pendulum’s moment of inertia. As a direct result, the systematic torque arising from AE errors is suppressed to a residual level of ${10}^{-17}\mathrm{N}\mathrm{m}$. Finally, we discuss pathways to reduce the calibration uncertainty by an additional order of magnitude, which would establish this technique as a stand-alone method for high-precision AE calibration.

We present a time-dependent end-to-end framework for laser power beaming from cislunar orbits to the lunar surface. The model links on-orbit generation (solar arrays and wall plug to optical), terrain-masked visibility and range, beam propagation with realistic divergence and jitter, and surface conversion with thermal and dust limits, returning delivered daily energy. Baseline loads for early polar activities [habitat survival, mobility, communications and navigation (comm/nav), pilot in situ resource utilization (ISRU)] set target $\mathrm{W}\mathrm{h}{\mathrm{day}}^{-1}$ values and are used consistently in scaling laws and design maps. A near-rectilinear halo orbit (NRHO) to a Shackleton-rim site provides a worked example: for a 2-m-class phased array at 1064 nm, the reference geometry yields approximately $0.6–0.8\mathrm{kW}\mathrm{h}{\mathrm{day}}^{-1}$ to a $1{\mathrm{m}}^2$ receiver (about 28 W averaged over the day). We place this result in context by comparing on the same daily-energy metric to surface photovoltaics (PVs) with storage and to compact fission, and by showing how the delivered energy scales nearly linearly with the transmit power and as $D_{\mathrm{eff}}^2$ via encircled-energy capture, with a multiplicative gain from visibility (constellations). The same framework indicates practical regimes already within reach: e.g., a 10-m effective-aperture optical phased array at $P_{\mathrm{tx}}=100$ kW delivers approximately $30–50\mathrm{kW}\mathrm{h}{\mathrm{day}}^{-1}$ at polar sites with typical single-orbiter visibility, as quantified by the delivered-energy and sizing maps. Thus, laser beaming is mass competitive where darkness or permanent shadow forces deep storage for PV, or where distributed and duty-cycled users can amortize a shared transmitter; compact fission retains advantage for continuous multikilowatt baseload at fixed sites.

Simulated bifurcation (SB) algorithms, inspired by quantum adiabatic evolution, have shown promise in addressing combinatorial optimization problems through efficient parallel processing. However, despite their ability to leverage parallelism by evolving independent search trajectories, a major limitation of SB algorithms lies in their fully decentralized architecture, which lacks mechanisms for interparticle communication, often resulting in redundant exploration and suboptimal convergence. To address this limitation, globally guided simulated bifurcation (GSB) algorithms are proposed. These variants transform SB’s independent parallel processes into a cooperative swarm, where particles dynamically share positional data and receive stochastic perturbations to navigate energy landscapes collectively. Numerical experimental validation on the Gset dataset (graphs up to 3000 nodes) and the fully connected graph K2000 demonstrates that GSB consistently reduces the time to solution compared with SB. Moreover, GSB achieves competitive or superior performance relative to Free Energy Machine across the benchmark instances. This work establishes a new direction in quantum-inspired optimization by demonstrating that controlled information sharing among parallel processors can overcome fundamental limitations in adiabatic algorithms while retaining their hardware-friendly parallelism.

Free-space continuous-variable quantum key distribution (CV-QKD) is attractive for its low cost, operational simplicity, and deployment flexibility. Discrete modulation further enhances practicality, yet rigorous security analysis over free-space channels is challenging because turbulence-induced fluctuations are compounded by the non-Gaussian nature of discrete modulation. We perform a fully numerical characterization of the free-space quantum channel, avoiding the simplifying assumptions inherent in existing analytical models. Together with a semidefinite-programming method, we establish an asymptotic security analysis framework of free-space discrete modulated (DM) CV-QKD without invoking Gaussian optimality. Unlike the cutoff behavior implied by the analytical models of transmittance probability distribution, our numerical results exhibit a pronounced long tail, indicating that the models assign larger probability mass to low transmittance and might overestimate turbulence-driven fluctuations. Based on the precise channel characterization, we compute tight lower bounds on the asymptotic secret key rate (SKR) under weak and moderate turbulence, and systematically assess postselection strategies. We find that optimized amplitude postselection increases the SKR, whereas phase postselection consistently degrades it. Additionally, in the absence of finite-size effects, transmittance-based postselection yields further gain.

Passive-state-preparation continuous-variable quantum key distribution (CVQKD) leverages the inherent field fluctuations of thermal source for quantum state preparation, thereby eliminating the need for modulators and quantum random number generators. It not only contributes to the development of low-cost, miniaturized CVQKD systems, but also inherently closes all modulation-related security loopholes. Despite its advantages in facilitating scalable and cost-effective QKD networks, current passive-state-preparation CVQKD implementations remain confined to point-to-point configurations, constrained by low secret key rates and the lack of rigorous security proofs for multiuser protocols. In this work, we propose a point-to-multipoint (PTMP) CVQKD protocol with passive-state preparation, supported by a comprehensive security framework that enables simultaneous and independent key generation between the passive state source and all end users. Simulation results demonstrate that the protocol can support hundreds of users over transmission distances of tens of kilometers, making it highly suitable for metropolitan-area and access-network applications. The simplified source preparation, combined with concurrent key generation, lays the foundation for a high-performance and scalable CVQKD network, offering a practical and efficient pathway toward the realization of large-scale QKD infrastructures.

Electrons floating on solid neon exhibit long charge-coherence times, making them attractive for hybrid quantum systems. When combined with high-quality high-impedance superconducting resonators and a local magnetic field gradient, this platform enables strong charge-photon and spin-charge coupling—key ingredients for scalable spin-qubit architectures. In this work, we demonstrate that $\mathrm{Nb}$-$\mathrm{Ti}$-$\mathrm{N}$ nanowire resonators maintain high quality factors around ${10}^5$ after depositing solid neon onto the resonators and subsequently loading electrons onto the neon surface, validating their suitability for electrons-on-neon platforms. Building on these experimental results, we theoretically analyze micromagnet designs and coupling strategies that can enable spin-photon interactions in this platform. Our analysis outlines performance targets for next-generation devices, showing that, at the charge sweet spot, spin-qubit gate fidelities exceeding 99.99% for single-qubit operations and 99.9% for two-qubit operations are achievable with natural neon.

Self-oscillator devices based on a negative differential resistance (NDR) offer a promising foundation for oscillator-based computing—an emerging computational paradigm that exploits the synchronization, phase dynamics, and collective behavior of coupled nonlinear oscillators for efficient pattern recognition, temporal coding, and signal processing—as well as for implementing spiking neural networks. In this work, we present a compact, thyristor-based two-terminal device that exhibits an ultrasmooth, hysteresis-free NDR response, enabling precise and robust control over complex temporal dynamics. Through a combination of experimental measurements and numerical simulations, we demonstrate that the system supports a tunable Hopf bifurcation, with oscillatory behavior modulated by input current and capacitance. As capacitance increases, the oscillations transition smoothly from sinusoidal to relaxation-type waveforms. The underlying bifurcation structure is analyzed analytically and visualized through dynamical trajectories. Importantly, when operated near the bifurcation threshold, the device exhibits stochastic resonance, amplifying weak periodic signals in the presence of noise, and yielding a 6.8-dB improvement in signal-to-noise ratio. These results establish a neuromorphic-compatible, low-power architecture that bridges nonlinear device physics with functional applications in temporal computation and brain-inspired hardware.

For spin-polarized ensembles of alkali-metal atoms with hyperfine structure and spin greater than $1/2$, the interplay between spin dynamics and quantum noise mechanisms remains largely unexplored, especially in the spin-exchange-relaxation-free (SERF) regime. In particular, the theoretical understanding of the dynamics for the mean values of the spin operators was established shortly after the advent of optical pumping. In contrast, a corresponding theory for spin fluctuations has not yet been developed, and is addressed in this work. Here, we develop such a first-principles theory of spin fluctuations in alkali-metal vapors. The nonlinearity bottleneck of spin-exchange collisions, which dominate the physics of such vapors, is overcome by linearizing the dynamics around the equilibrium density matrix. The result is a precise calculation of the absolute magnetic sensing limit of optically pumped atomic magnetometers, which can precisely benchmark quantum limited and quantum enhanced protocols, in contrast to the traditional approach shown to be adequate only within a factor of 2. Further, we elucidate how signal and noise in atomic magnetometers are distributed among the spin eigenmodes defined under continuous optical pumping and probing via the paramagnetic Faraday rotation. Notably, in the SERF regime, alongside the magnetic resonance narrowing, we find a reduction of spin noise at the spin-precession frequency as a consequence of strong hyperfine correlations redistributing spin noise, when both hyperfine manifolds are simultaneously probed. These insights can lead to improved quantum devices utilizing alkali-metal atoms or similar spin-based sensing platforms.

An optical lattice is a periodic light crystal constructed from the standing-wave interference patterns of laser beams. It can be used to store and manipulate quantum degenerate atoms and is an ideal platform for the quantum simulation of many-body physics. A principal feature is that optical lattices are flexible and possess a variety of multidimensional geometries with modifiable band structure. An even richer landscape emerges when control functions can be applied to the lattice by modulation of the position or amplitude with Floquet driving. However, the desire of realizing high-modulation bandwidths while preserving extreme lattice stability has been difficult to achieve. In this paper, we demonstrate an effective solution that consists of overlapping two counterpropagating lattice beams and controlling the phase and intensity of each with independent acousto-optic modulators. Our phase controller mixes sampled light from both lattice beams with a common optical reference. This dual heterodyne locking method allows exquisite determination of the lattice position, while also removing parasitic phase noise accrued as the beams travel along separate paths. We report up to 50 dB suppression in lattice phase noise in the 0.1–1 Hz band, along with significant suppression spanning more than 4 decades of frequency. The absolute phase diffusion of the lattice position is only 10 Å when integrated over 10 s. This method permits precise, high-bandwidth modulation (greater than 50 kHz) of the optical lattice intensity and phase. We demonstrate the efficacy of this approach by executing intricate time-varying phase profiles for atom interferometry.