Precision sensing and imaging of weak static magnetic fields are crucial for a variety of emerging nanoscale applications. While nitrogen-vacancy (NV) centers in diamond provide exceptional ac magnetic field sensitivity with nanoscale spatial resolution, their sensitivity to static (dc) magnetic fields is fundamentally limited by the short dephasing time ($T_2^{*}$) due to spin-spin interactions. In this work, we present a hybrid sensing approach that integrates a soft ferromagnetic microwire with a single near-surface NV center to amplify its response to external static magnetic fields. This hybrid configuration achieves a dc magnetic field sensitivity of $63\mathrm{nT}/\sqrt{\mathrm{Hz}}$ for a single NV center—about 500 times greater than conventional inhomogeneous broadening- or $T_2^{*}$-limited magnetometry, with potential for further enhancement. The compact and highly sensitive nature of this sensor opens new opportunities for quantum sensing applications involving the detection of static or slowly varying magnetic fields across diverse scientific and technological domains.

Nondegenerate two-photon absorption (ND-TPA) detection has emerged as a highly promising approach for room-temperature mid-infrared (MIR) imaging by exploiting the nonlinear interaction between infrared photons and pump radiation in wideband gap semiconductors. However, scaling ND-TPA imagers toward wide-field operation remains challenging because the nonlinear interaction strength rapidly decreases with enlarged sensing area, thereby degrading detection sensitivity. Here, we demonstrate a wide-field MIR single-pixel ND-TPA imaging system, in which two-photon optical encoding is implemented in a direct-band gap GaAs photomultiplier tube with large photosensitive area and high internal gain. By combining spatial multiplexing with single-element integrated detection, the proposed scheme effectively enhances the collection and accumulation of weak nonlinear signals under a pump irradiance significantly lower than previous requirements. Moreover, the system achieves a spatial resolution of $44\mathrm{\mu }\mathrm{m}$ over a 4-mm field of view, corresponding to a record-high space-bandwidth product of $6.5\times {10}^3$ among existing TPA-based MIR imagers. This work establishes a scalable pathway toward wide-field and high-sensitivity MIR computational imaging, with promising applications in industrial inspection, remote sensing, and weak-target detection.

Active control of chiroptical responses in metasurfaces is critical for advancing photonic spin-selective technologies. Here, we propose and experimentally demonstrate a multifunctional chiral metasurface based on the phase-change material of vanadium dioxide (${\mathrm{VO}}_2$) that offers triple-state switching in circular dichroism. Dual channels of external electric voltages were adopted to independently drive the phase transition of two respective ${\mathrm{VO}}_2$ islands in a planar metasurface unit, where the selective control on the left-handed chiral, right-handed chiral, and achiral responses was experimentally achieved. Our method enables discrete switching between positive, zero, and negative chirality, as well as continuous circular dichroism strength tuning, surpassing the conventional single chiral state modulation. Such a dual-channel control method offers an easy pathway toward dynamic spin photonics and adaptive chiral optical components.

Unlike the conventional non-Hermitian skin effect (NHSE) that localizes bulk wave functions to the boundary, the hybrid skin-topological effect (HSE) arises from the interplay between topological edge states and the non-Hermitian skin effect, resulting in the further localization of edge state wave functions at the corners of the sample. While the HSE has been observed in passive platforms, these experimental investigations have generally been constrained by inherent material dissipation, often restricting observations to comparison or indirect reconstructions. In such systems, rapid energy dissipation made it difficult to determine whether localization originated from non-Hermitian physical mechanisms or simple energy loss, posing a significant challenge for the direct observation of the non-Hermitian skin states. Here, we introduce the complex-frequency excitation technique into a two-dimensional acoustic coupled-ring network to overcome the loss limits, successfully enabling the direct observation of the spin-dependent transient HSE. Our experiments clearly visualize the dynamic evolution of edge states with distinct pseudospins as they accumulate at opposite corners over time. This work not only establishes a pathway for detecting non-Hermitian eigenstates in lossy systems but also provides a versatile platform for the development of pseudospin-controlled topological acoustic devices.

Variational quantum algorithms offer a promising route to combinatorial optimization, but their applicability is limited by the challenge of encoding large-scale problems within restricted qubit resources. In this work, we introduce a qubit-efficient variational framework based on Pauli correlation encoding (PCE) and apply it to electric power demand portfolio optimization. Binary variables are represented through expectation values of Pauli correlation operators, which encode multibody correlations of the quantum state and provide a continuous relaxation enabling compact representations with few qubits. We further propose a two-stage hybrid formulation, in which a time-averaged problem provides initialization for a time-resolved optimization. Numerical simulations demonstrate near-optimal performance across problem sizes ranging from $m=18$ to $\mathrm{10,296}$, with normalized cost gaps on the order of ${10}^{-4}$ relative to solutions with certified optimality. We show that the performance is governed by the interplay between continuous relaxation and discretization: the effective resolution of the correlator representation determines how reliably improvements in the continuous loss translate into better discrete solutions, with larger systems exhibiting more consistent behavior. Finally, we demonstrate robustness on a trapped-ion quantum processor, where high-quality solutions are obtained despite noise and finite sampling. These results establish PCE as a physically motivated and qubit-efficient framework for large-scale combinatorial optimization.

After modeling the surface gap, the bulk gap, and the electrode-material interface gap, and considering the effect of spin-orbit coupling strength on the effective mass, we reveal that the surface quasipolarons at the edge states are the main charge carrier of nonlinear photocurrent in a double perovskite family of ${\mathrm{Ca}}_{\mathrm{x}}{\mathrm{Cu}}_{4-x}{\mathrm{Ti}}_4{\mathrm{O}}_{12}$ ($x=3$, 2, and 1). The photocurrent is the quadratic function of voltage, which is measured in two ways of the bulk mode and the surface mode, in the visible light with the wavelength of 385, 405, 450 and 660 nm and at the temperature of 150, 180, 210, 240, 270, and 300 K, respectively. When there is the electrode effect, we discuss the electron-phonon coupling, the spin-orbit coupling, the effective mass, the flat band, and the quasipolaron size. Particularly in the surface mode, we estimate the spin-orbit coupling and the electron-phonon coupling. The computational and experimental results suggest that the antiferromagnetically dielectric insulator in the ceramic form is a potential candidate for broad-spectrum and wide-temperature-range photodetectors.

We investigated the competing mechanisms of spin Hall magnetoresistance (SMR) and ordinary magnetoresistance (OMR) in van der Waals A-type antiferromagnet ${\text{CrPS}}_4/\text{Pt}$ heterostructures. By engineering the Pt thickness, we demonstrate a clear crossover from an SMR-dominated regime in thin (5 nm) Pt bilayers to an OMR-dominated regime in thick (30 nm) ones, providing a reliable protocol for isolating the elusive SMR signal from the OMR signal. Strikingly, a robust SMR persists at room temperature, far exceeding the bulk Néel temperature ($T_{\mathrm{N}}\approx 38\mathrm{K}$), which we attribute to a magnetic proximity-induced interfacial state. A field-dependent phase shift in the SMR angular response across $T_{\mathrm{N}}$ reveals that this interfacial magnetism is distinct from the bulk antiferromagnetic order. Complementary anomalous Hall effect measurements independently confirm the existence of this interfacial magnetization. Our work not only establishes ${\text{CrPS}}_4$ as a promising room-temperature spintronic material but also establishes thickness-dependent magnetotransport as a powerful tool for probing interfacial magnetic phenomena in antiferromagnetic heterojunctions.

Spatial photonic Ising machines (SPIMs) exploit free-space Fourier propagation to perform parallel optical computation of spin-spin couplings, providing a promising platform for large-scale combinatorial optimization. However, their fidelity is limited by intrinsic optical aberrations and nonuniform incident-field amplitudes, which distort the mapping between the modulating plane and the corresponding Fourier plane, thereby degrading energy resolution and annealing reliability. In this work, we propose an in situ differentiable complex-field calibration framework. Based on paired random phase patterns and Fourier-plane captured intensity distributions, the implicit system error can be numerically backpropagated to an exact complex-amplitude distribution on a pixel sampling grid. In single-spin-flip tests, the typical relative deviation between the measured energy and the theoretical value is reduced to 1.31%. Under general SPIM annealing settings, the coefficient of determination between the experimental and theoretical Hamiltonian reaches 0.9998. This work provides a plug-and-play in situ calibration route toward ultrahigh Hamiltonian-evaluation fidelity in more complicated SPIMs.

The centroid oscillation of an offset laser pulse propagating in a preformed plasma channel is investigated through theoretical analysis and three-dimensional particle-in-cell simulations. For nonrelativistic laser pulses, the mode leakage of a finite channel and the temporal walk-off between the fundamental and high-order modes of a finite-duration laser induce a decay in the laser centroid oscillation. An analytical model characterizing these decay mechanisms is derived and validated by simulations. For relativistic laser pulses, the slice-based centroid oscillation frequency develops an axial chirp due to relativistic channel modification and photon deceleration. This chirp leads to phase mixing across different axial slices of the pulse, resulting in a rapid damping of the overall centroid oscillation. Understanding this oscillation damping is crucial for mitigating electron beam-pointing jitter and maintaining beam quality in high-energy, channel-guided laser wakefield accelerators.

The transconductance $g_m=d{I}_D/d{V}_G$ of a field-effect transistor (FET) is conventionally read as a proxy for carrier density. We show that it is instead a spectroscopic probe of the carrier distribution: because $g_m$ weights the spectral current $j(E)$ by the gate-voltage derivative $\partial f(E)/\partial V_G$ and integrates over energy, it is sensitive to the shape of $f(E)$, not merely its integrated weight $n$. We develop an energy-resolved transport framework for two-dimensional (2D) FETs and, within a gate-independent spectral-kernel approximation, derive the decomposition $g_m=g_m^{(n)}+g_m^{(\alpha )}$ into the conventional density-modulation term $g_m^{(n)}$ and a distribution-shape-driven term $g_m^{(\alpha )}$. The latter, obtained as the residual after subtracting the smooth density-modulation background from the measured $g_m$, exhibits a characteristic anomalous peak at a gate voltage $V_G^{\text{pk}}$. This peak has no counterpart in equilibrium transport and cannot be explained by carrier density modulation alone. With the spectral kernel calibrated, the peak position and height—extracted from standard dc/lock-in $g_m$ sweeps—constrain the hot-carrier energy $E_0$, spectral width $\sigma$, and generation threshold $n_c$, realizing a steady-state, all-electrical spectroscopy of the carrier distribution. An optional time-resolved extension further recovers the carrier relaxation time $\tau$ from the transient response following a pump excitation, establishing the 2D FET as a distribution-function spectrometer that requires no optical readout.

Time-continuous quantum error correction, necessary to protect quantum information under time-dependent Hamiltonians, relies on weak continuous syndrome measurements. Implementing these measurements requires a continuous coupling among at least two qubits and a meter, a demanding requirement. We show that, under continuous operation, common parity-measurement protocols in the circuit quantum electrodynamics platform corrupt the logical information. The failure arises from approximating the three-body interaction by a sum of two-body couplings to the meter, which prevents simultaneous suppression of measurement backaction on the logical and error subspaces. We argue that the same mechanism applies more generally beyond the circuit quantum electrodynamics setting. Taken together, our results impose a practical limitation on continuous stabilizer quantum error correction and point to the viable alternatives—architectures that realize native three-body interactions or erasure-based encodings in which the error subspace need not be protected.

We propose a method of spatial resolution enhancement in metrology (thermometry, magnetometry, pH estimation, and similar methods) using blinking fluorescent nanosensors by combining sensing with superresolution optical fluctuation imaging. By utilizing the idea of quantum superresolution imaging by photon statistics, the applicability of the proposed methodology is extended to the low-brightness regime. The efficiency of the approach is demonstrated by numerical simulations performed for several model configurations, representing steplike and continuous variation of the sensed parameter, high- and low-brightness regimes, and one- and two-dimensional structures. The second- and fourth-order cumulant images provide improvement of the contrast and enable successful reconstruction of smaller features of the modeled parameter distribution relatively to the intensity-based approach. We believe that blinking fluorescent sensing agents, when complemented with the developed image analysis technique, could be routinely utilized in the life science sector to recognize the local changes in the spectral response of blinking fluorophores, such as those delivered targetly to a specific cell or even organelle. It is extremely useful for the local measurements of changes in living cells’ physical parameters due to applying any external “forces,” including disease effects, aging, healing, or response to treatment.

Floquet engineering of cavity magnon-polaritons by periodically modulating the magnon frequency has recently attracted much interest as a way to manipulate the energy spectrum of magnon-photon hybrid systems. However, modulating the frequency of magnons by a time-varying bias magnetic field can be challenging. We demonstrate cavity magnon-polariton Floquet engineering by modulating the microwave cavity frequency, allowing large modulation depth and bandwidth. We apply commensurate two-frequency Floquet modulations with the higher frequency at twice and three times the lower frequency and demonstrate that the resulting spectrum depends on the relative amplitude and phase of the two drive tones. In comparison with single-frequency Floquet modulations, the spectrum has qualitatively different features; in particular, new anticrossings appear between previously uncoupled sidebands. Our platform offers an alternative way to manipulate Floquet quasienergy levels in hybrid systems.

We present a continuous-time, neural-network-based approach to optimal control in quantum systems, with a focus on pulse engineering for quantum gates. Leveraging the framework of neural ordinary differential equations (neural ODEs), we construct control fields as outputs of trainable neural networks, thereby eliminating the need for discrete parametrization or predefined bases. This allows for the generation of smooth, control-hardware-agnostic pulses that can be optimized directly using differentiable integrators. As a case study, we design and experimentally implement a short and detuning-robust $\pi /2$ pulse for photon number parity measurements in superconducting transmon circuits. This is achieved through simultaneous optimization for robustness and suppressing the leakage outside of the computational basis. These pulses have very high fidelity ($\approx 99.95\%$) and realize the parity measurement with an efficiency greater than 99.9% over a detuning range of $\approx \pm 20\mathrm{MHz}$, thereby outperforming traditional techniques while retaining comparable gate durations. This showcases the potential of neural ODEs for high-performance quantum control in experimentally relevant settings.

Lightsails are promising spacecraft that can traverse interstellar distances within decades via radiation-pressure propulsion from high-power lasers. The envisioned missions crucially rely on the sail being confined within the propelling laser beam, requiring restoring and damping mechanisms for both translational and rotational degrees of freedom. Here, we use a two-dimensional rigid model to show that full asymptotic stability of planar nanophotonic sails can be achieved through purely optical, relativistic forces and torques, which damp all unstable degrees of freedom. By judiciously optimizing the angular and frequency dispersion of diffraction gratings, we find that damping can be substantially enhanced compared with plane-mirror sails. Over the full operating band for $0.2c$ missions, it is several times larger, while over narrow wavelength bands, the enhancement is by 3 orders of magnitude. Therefore, relativistic effects can, in principle, provide comprehensive and realistic control over lightsail motion.

We report the results of two-photon-excited fluorescence (TPEF) measurements of the $5S_{1/2}\to 5D_{5/2}$ transition of ${}^{85}\mathrm{Rb}$ and ${}^{87}\mathrm{Rb}$ cooled in a magneto-optical trap. We observe TPEF at excitation powers as low as $1\mathrm{\mu }\mathrm{W}$ or fluxes as low as ${2.98}_{-0.94}^{+1.37}\times {10}^{18}\text{photons}{\text{cm}}^{-2}{\mathrm{s}}^{-1}$ (${}^{85}\mathrm{Rb}$) and ${3.31}_{-1.33}^{+2.21}\times {10}^{18}\text{photons}{\text{cm}}^{-2}{\mathrm{s}}^{-1}$ (${}^{87}\mathrm{Rb}$). Our results demonstrate that optically cooled Rb is a promising platform for observing sensitive two-photon spectral signatures at low photon fluxes.