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.

Graphene nanoribbon (GNR) emerges as an exceptionally promising channel candidate due to its tunable sizable band gap (0–3 eV), ultrahigh carrier mobility (up to $4600{\mathrm{cm}}^2{\text{V}}^{-1}{\text{s}}^{-1}$), and excellent device performance (current on-off ratio of ${10}^7$). However, the asymmetry of reported $n$-type and $p$-type GNR field-effect transistors (FETs) at ultrashort gate length $(L_{\mathrm{g}})$ has become an obstacle to future complementary metal-oxide-semiconductor (CMOS) integration. Here, we conduct ab initio quantum transport simulations to investigate the transport properties of sub-5-nm $L_{\mathrm{g}}$ 7-armchair-edge hydrogened GNR (7 AGNRH) FETs. The on-state current, delay time, and power dissipation of the $n$-type and $p$-type 7 AGNRH FETs fulfill the International Technology Roadmap for Semiconductors targets for high-performance devices when $L_{\mathrm{g}}$ is reduced to 3 nm. Remarkably, the 7 AGNRH FETs exhibit superior $n$-type and $p$-type symmetry to the 7-9-7 AGNRH FETs due to the more symmetrical electron and hole effective masses. Compared with the monolayer ${\mathrm{MoS}}_2$ and ${\text{MoTe}}_2$ counterparts, the 7 AGNRH FETs have better device performance, which could be further improved via gate engineering. Our results shed light on the immense potential of 7 AGNRH in advancing CMOS electronics beyond silicon.

We present a superconducting qubit, which consists of two strongly coupled modes: one for data storage and one for coupling, allowing faster, higher-fidelity entangling gates and readout. The use of a dedicated coupling mode allows nonlinear couplings of several hundred MHz between the data mode and other elements, with minimal linear coupling to the data mode. Including decoherence, simulations show that this architecture enables microwave-only cz gates with an infidelity of $8.7\times {10}^{-5}$ in 17 ns and always-on $ZZ$ interaction less than 0.4 kHz. Numerical simulations also show readout with state assignment error of $1\times {10}^{-3}$ in 38 ns (assuming quantum efficiency $\eta =0.5$). Our readout scheme naturally reduces Purcell decay to negligible levels without a Purcell filter and provides a mechanism to suppress shot noise dephasing times to the 10 ms level when not performing readout. Single-qubit gate infidelities are below $1\times {10}^{-5}$ including decoherence. These beyond experimental state-of-the-art gate and readout fidelities rely only on capacitive coupling between arm qubits, making the arm qubit a promising scalable building block for fault-tolerant quantum computers.

Exciplex-based organic light-emitting diodes (EX-OLEDs) include interfacial- and bulk-heterojunction devices, and the external quantum efficiency (EQE) of the bulk device is typically higher than that of the interfacial one when fabricated with the same donor and acceptor materials. Although photoluminescence (PL) and transient PL were used to find that this higher EQE is attributed to the enlarged electron-hole recombination zone, its further reasons are still vague. Here, organic magnetic field $(B)$ effects (OMFEs), including magneto-electroluminescence (MEL), magneto-conductance (MC), and magneto-efficiency ($\mathrm{M}\eta$), are used to find new reasons for the improved EQE. Specifically, low-field effects ($|B|\le 10\mathrm{mT}$) of both MEL and $\mathrm{M}\eta$ traces from the interfacial and bulk devices, respectively, show the $B$-mediated intersystem crossing (ISC) and reverse ISC (RISC) features. Furthermore, although both low-field effects of their MC traces exhibit the $B$-mediated ISC feature, the ISC magnitude of the bulk device is lower than that of the interfacial one under the same injection currents. That is, the low-field effects of their OMFE traces reflect that the RISC process from triplet to singlet EX states (${\text{EX}}_3\to {\text{EX}}_1$) in the bulk device is stronger than that in the interfacial one since these low-field effects are determined by the superposition of the $B$-mediated ISC and RISC processes. Moreover, all high-field effects ($10<|B|\le 300\mathrm{mT}$) of their OMFE traces show the $B$-mediated triplet-charge annihilation (TCA) between ${\text{EX}}_3$ and free charges (${\text{EX}}_3+q\to {\text{S}}_0+q^{\prime }$), but the TCA magnitudes of the bulk device are lower than those of the interfacial one under the same injection currents, indicating a weaker TCA process in the bulk device than that in the interfacial one. This is because the enlarged electron-hole recombination zone increases the quantity of the intermolecular contacts between donor and acceptor materials, causing a higher recombination efficiency in the bulk device than that in the interfacial one. The improved recombination efficiency will increase the quantity of ${\text{EX}}_3$ and reduce that of free charges, which results in the enhanced RISC and weakened TCA, respectively. The weakened TCA still increases the quantity of ${\text{EX}}_3$ and then further enhances RISC, leading to the elevated singlet/triplet ratio and the improved device EQE. Therefore, this work not only uses OMFEs to reveal novel physical mechanisms of the higher EQE from the bulk device than that from the interfacial one, but also paves the way for further developing high-efficiency bulk-heterojunction EX-OLEDs.

We present a nonperturbative tensor-network approach to the excitation spectra of superconducting circuits based on Josephson-junction arrays. These arrays provide the large lumped inductances required for qubit designs, yet their intrinsically many-body nature is typically reduced to effective single-mode descriptions. Perturbative treatments attempt to include the collective array modes neglected in these approximations, but a fully nonperturbative analysis is challenging due to the many-body structure and the collective character of these modes. We overcome this difficulty using the DMRG-X algorithm, which extends tensor-network methods to excited states. Our key advance is a construction of trial states from the linearized mode structure, enabling direct computation of excitations, even in degenerate manifolds, which was previously inaccessible. Our results reveal significant deviations from, and allow us to improve upon, previous perturbative treatments in the regime of low array junction impedance.

As superconducting quantum processors continue to scale, high-performance quantum control becomes increasingly critical. In densely integrated architectures, unwanted interactions between nearby qubits give rise to crosstalk errors that limit operational performance. In particular, direct exchange-type ($\mathit{XY}$) interactions are typically minimized by designing large frequency detunings between neighboring qubits at the hardware level. However, frequency crowding in large-scale systems ultimately restricts the achievable frequency separation. While such $\mathit{XY}$ coupling facilitates entangling gate operations, its residual presence poses a key challenge during single-qubit controls. Here, we propose a scalable pulse-level control framework, incorporating frequency modulation and dynamical decoupling to suppress $\mathit{XY}$ crosstalk errors. This framework operates independently of coupling strengths, reducing calibration overhead and naturally supporting multiqubit connectivity. Numerical simulations show orders-of-magnitude reductions in infidelity for both idle and single-qubit gates in a two-qubit system. We further illustrate scalability in a five-qubit layout, where crosstalk between a central qubit and four neighbors is simultaneously suppressed. Our crosstalk suppression framework provides a practical route toward high-fidelity operation in dense superconducting architectures.