Superinductances are superconducting circuit elements that combine a large inductance with a low parasitic capacitance to ground, resulting in a characteristic impedance exceeding the resistance quantum $R_Q=h/(2e{)}^2\simeq 6.45\mathrm{k}\mathrm{\Omega }$. In recent years, these components have become key enablers for emerging quantum circuit architectures. However, achieving high characteristic impedance while maintaining scalability and fabrication robustness remains a major challenge. In this work, we present two fabrication techniques for realizing superinductances based on vertically stacked Josephson junctions. Using a multiangle Manhattan (MAM) process and a zero-angle (ZA) evaporation technique—in which junction stacks are connected pairwise using airbridges—we fabricate one-dimensional chains of stacks that act as high-impedance superconducting transmission lines. Two-tone microwave spectroscopy reveals the expected $\sqrt{n}$ scaling of the impedance with the number of junctions per stack. The chain fabricated using the ZA process, with nine junctions per stack, achieves a characteristic impedance of approximately $16\mathrm{k}\mathrm{\Omega }$, a total inductance of $5.9\text{μ}\mathrm{H}$, and a maximum frequency-dependent impedance of $50\mathrm{k}\mathrm{\Omega }$ at 1.4 GHz. Our results establish junction stacking as a scalable, robust, and flexible platform for next-generation quantum circuits requiring ultrahigh impedance environments.

Low-loss inductors are essential components in various superconducting circuits, such as qubits or digital electronics. In this study, we investigate highly compact inductors formed by vertically stacking Josephson junctions. Our implementation employs several layers of aluminum separated by tunnel barriers. Individual stacks are connected by suspended superconducting bridges, which are free of additional dielectric materials and, therefore, should not contribute significantly to losses. We present implementation details, fabrication results, and device characterization measurements.

Hardware-algorithm co-design provides an effective route for implementing quantum optimization on near-term hardware. Counterdiabatic (CD) protocols can accelerate adiabatic optimization but are difficult to realize digitally due to increased circuit depth and noise sensitivity. Here, we report a photonic co-design strategy that directly implements CD dynamics on a programmable photonic integrated circuit based on a Mach-Zehnder interferometer mesh. By exploiting the ability of the photonic processor to realize arbitrary unitary transformations, our approach bypasses gate-level decomposition and significantly reduces circuit depth. We further enhance the protocol by mitigating higher-order many-body terms in conventional CD optimization. An experimental demonstration of integer factorization achieves success probabilities up to 86% with only three layers, together with accelerated energy convergence, highlighting programmable photonic platforms for quantum optimization.

Two-level systems (TLSs) are a dominant decoherence mechanism in superconducting qubits, microwave kinetic inductance detectors, and quantum dots. TLSs are tunneling states commonly found in amorphous materials and interfaces, which interact electromechanically, leading to energy loss. Fluctuations in the frequency of the TLSs are a significant problem for qubit operation and force recalibration every few hours. In this study, we probe the effect of alternating bias at cryogenic temperatures on TLSs in a purpose-built LC oscillator. When an in situ alternating bias is applied, the steady-state spectra of the TLSs disappear. Spectroscopy reveals transient behavior, in which the TLS frequency fluctuates on the order of minutes. Thermal cycling above 10 K reverses these effects, restoring the TLS spectrum to its original state. Importantly, the intrinsic loss tangent of the LC oscillator remains unchanged before and after the application of the alternating bias. We propose that the disappearance of the steady-state spectrum is caused by nonequilibrium energy buildup from strain in the oxide film introduced by the pulsed voltage-bias sequence. Understanding this nonequilibrium energy could shed light on TLS fluctuations and reduce the calibration requirements for qubits.

Measurement-device-independent quantum key distribution (MDI-QKD) can be immune to all detector-side loopholes. Compared with weak-coherent-state sources, heralded single-photon sources (HSPSs) can effectively suppress vacuum components, and thus substantially improve the transmission distance and secure key rate of MDI-QKD. Here, we experimentally demonstrate an efficient MDI-QKD protocol based on HSPSs without vacuum sources [Phys. Rev. A 98, 032303 (2018)]. It achieves a secure key rate that is more than 60 times higher than the previous reported work at 10-dB transmission loss and extends the maximum transmission loss to more than 30 dB. These improvements are attributed to the efficient protocol used and the high-quality HSPSs prepared in the experiment, which enable a Hong-Ou-Mandel interference visibility of 95.1% at 10 mW. Furthermore, with improvements to experimental technology, the maximum transmission distance is expected to exceed 400 km. Therefore, the current work is expected to play a crucial role in the future development of large-scale quantum communication networks.

We develop a quantitative model of ionization processes in biological tissues under ultrahigh-dose-rate (UHDR) radiation. The underlying conjecture is that of electron-hole liquid (EHL) formation in water-based substances of biological tissues. Unlike the earlier known EHL in semiconductor crystals, the charge carriers here are poorly mobile, owing to strong interactions with the background (solvated electrons, etc.); hence, EHL resembling ionic melts is formed. Similar to all ionic systems, Coulomb coupling makes that EHL energetically favorable that leads to recombination barriers, suppressing subsequent structural transformations. In particular, the generation of secondary reactive species in such an EHL becomes limited, translating into a reduction of biological damage and tissue-sparing effects. We show how these processes are sensitive to the tissue quality and frequency dispersion of the dielectric permittivity. Equations for dose and dose rate defining the sparing thresholds are derived.

Spin-decoupled metasurfaces hold significant potential for integrated photonics by enabling independent manipulation of the spin degree of freedom of light. However, achieving robust spin-decoupled performance over both a broad bandwidth and a wide range of incident angles remains a pivotal challenge. In this work, a spin-decoupled strategy incorporating the propagation phase with the geometric phase is implemented to design plasmonic metasurfaces capable of independently controlling wave fronts of orthogonally circularly polarized light in the visible spectrum. Two representative devices demonstrate distinct spin-decoupled functionalities: one generating a vortex beam under left circular polarization (LCP) and the other enabling LCP-selective bifocusing, while both maintain specular reflection under right circular polarization. Systematic experimental characterization using microscopic spectroscopy demonstrates robust spin-decoupled performance across an 80 nm bandwidth and a wide range of incident angles with a scanning range of up to $40\text{μ}\mathrm{m}$. This dual advantage in spectral and angular stability, surpassing typical dielectric counterparts, provides solutions for reliable metasurface devices in applications such as multiplexed optical communications and miniaturized high-resolution imaging.

Compact models for two-dimensional field-effect transistors (2D FETs), predominantly adapted from conventional unipolar Si metal-oxide-semiconductor FET (MOSFET) frameworks, frequently fail to capture essential physics such as ambipolar conduction, threshold voltage roll-off, and output current upswing in saturation. While models based on Landauer formalism and the Pao-Sah approach offer partial solutions, their reliance on curve fitting and neglect of defects obscure the link to underlying device physics. Here, we introduce a physics-grounded carrier-phase-space (CPS) framework for 2D FET compact modeling. By employing the quasiequilibrium approximation and formulating the drain-source current as a path integral within the CPS, our model accurately describes threshold voltage roll-off, saturation current upswing, and ambipolar behavior. Crucially, analytical expressions for key electrical turning points across all operating regimes, including threshold voltage, saturation voltage, pinch-off voltage, and p-n-junction onset voltage, are derived for the first time through analysis of the bias-dependent integration path in CPS. Furthermore, the model incorporates the effects of ionized defects and is rigorously validated against experimental data from both ambipolar and unipolar FETs, demonstrating excellent electrostatic gating control and uniform thermal dissipation. This work establishes a comprehensive physics-based CPS compact model for 2D FETs, significantly advancing the foundation for their practical circuit design and manufacturing.

As one of the key frontiers of technological development in the modern world, rare-earth permanent magnets are now required to have a high maximum energy product and a Curie temperature, so as to meet the needs of today’s environmentally friendly technologies and applications. ${\mathrm{Sm}}_2{\mathrm{Fe}}_{17}{\mathrm{N}}_3$ is a promising rare-earth permanent magnet phase with a theoretical magnetic energy product of ≈59 MGOe, comparable with $\mathrm{Nd}$–$\mathrm{Fe}$–$\mathrm{B}$, and it contains no scarce heavy rare earths. The Curie temperature reaches 749 K and the corrosion resistance is excellent, making it suitable for high-temperature, high-stability applications. To understand magnetic properties and phase stability of ${\mathrm{Sm}}_2{\mathrm{Fe}}_{17}{\mathrm{N}}_3$ at high temperatures, we extracted a single-crystal nanoplate from powders and systematically investigated the evolution of the magnetic domains with temperature using advanced in-situ microscopy techniques and micromagnetic simulations. As the temperature increases from room temperature to 575 K, the nanoplates exhibit scalable mazelike magnetic domains, which is a reversible process driven by temperature-dependent magnetocrystalline anisotropy. When the temperature is further increased to 675 K, an irreversible domain evolution occurs, characterized by the formation of stripy magnetic domain walls and magnetic vortices. This phenomenon is associated with nitrogen escape from the lattice at the nanoscale due to its smaller activation energy (∼0.52 eV). The crystal structure remains stable until the temperature exceeds 675 K, at which point decomposition leads to the disappearance of the magnetic domains, indicating that the nitride nanomagnet exhibits promising thermal stability. This work advances the understanding of phase and magnetic stability in rare-earth nitrides, launching them as a promising platform for high-performance permanent magnetic applications.

We report on an experimental realization of multimaterial dielectric mirror coatings designed through a multi-objective optimization algorithm to simultaneously minimize thermal noise and optical losses. We validate this design strategy by fabricating and characterizing two distinct ternary systems: a ${\mathrm{Si}\mathrm{N}}_x$-based proof of concept and a ${\text{Ti::GeO}}_2$-based system targeting lower optical losses. The performance of the ${\mathrm{Si}\mathrm{N}}_x$ coating shows remarkable agreement with predictions, demonstrating a noise amplitude spectral density reduction of $0.82$ with respect to current reference coatings, and validating our design-to-fabrication pipeline. The ${\text{Ti::GeO}}_2$-based system achieves the crucial goal of sub-parts-per-million absorption; its measured thermal noise, however, is higher than the theoretically predicted level of $0.71$, extrapolated from single-layer material characterization. A dedicated tolerance analysis confirms that this discrepancy is not attributable to random thickness errors, emphasizing that further studies of the manufacturing process are needed to fully exploit this combination of materials. This work establishes a robust method for producing complex, high-performance optical coatings tailored for precision experiments.

The second-harmonic Hall technique is a widely used, sensitive method for studying the spin-orbit torques generated by charge current. It exploits the dependence of the Hall resistance on the magnetization direction, although thermal phenomena also contribute. Historically, deviations from the expected magnetic field dependence have usually been ignored. On the basis of our studies on permalloy/platinum bilayers, we show that a counterpart to the magnon-related spin-flip unidirectional magnetoresistance—known to appear in the second-harmonic longitudinal resistance—appears in the Hall data, and that describing the results in a wide field range with these contributions is essential to accurately estimate the torques.

We demonstrate a method to generate photons by injecting hot electrons into a p-n junction within a $\mathrm{Ga}\mathrm{As}$/$\mathrm{Al}\mathrm{Ga}\mathrm{As}$ heterostructure. Hot electrons are generated by biasing across a mesoscopic potential in the n-type region and travel toward the p-type region through a quantum Hall edge channel in the presence of a magnetic field perpendicular to the substrate. The p-type region is created several microns away from the hot-electron emitter by inducing interfacial charges using a surface gate. The energy relaxation of the hot electrons is suppressed by separating the orbitals before and after longitudinal-optical phonon emission. This technique enables the hot electrons to reach the p-type region and to recombine with induced holes followed by photon emission. Hot-electron-induced hole recombination is confirmed by a peak around 810 nm in an optical spectrum that corresponds to excitonic recombination in a $\mathrm{Ga}\mathrm{As}$ quantum well. An asymmetric structure observed in the optical spectrum as a function of the magnetic field originates from the chiral transport of the hot electrons in the Hall edge channel. We propose that the combination of our technology and an on-demand single-electron source would enable the development of an on-demand single-photon source embedded in a semiconductor wafer, which could accelerate the integration of on-chip scalable quantum optical circuits.

Spaceborne telescopes are critical components of gravitational wave observatories. The interaction between wave front aberrations and spacecraft jitter produces significant tilt-to-length noise, which ultimately limits measurement sensitivity. Although the impact of wave front error has been extensively studied, the influence of aperture diffraction on tilt-to-length coupling remains insufficiently explored. In this paper, an efficient optical model based on Fresnel impulse response theory is developed to simulate diffraction effects in scientific interferometers. A systematic analysis is conducted on how the first 36 Zernike aberration modes and their cross-coupling affect optical path stability, leading to the derivation of a normalized sensitivity matrix that identifies critical aberration types. Through Monte Carlo simulations, the influence of wave front quality on tilt-to-length noise is further quantified under practical constraints. The results demonstrate that a targeted suppression of jitter-sensitive aberrations, particularly those with even radial orders, can substantially reduce coupling noise. These findings provide theoretical foundations and practical strategies for optimizing the wave front error budget in future space-based gravitational wave detection missions.

Spintronic devices, such as magnetic tunnel junctions (MTJs), offer nonvolatility and ultralow power operation, making them promising candidates for building physical reservoirs in neuromorphic computing. However, realizing low-power and hardware-integrable reservoir computing (RC) systems remains a major challenge. In this work, we construct an echo-state network based on voltage-controlled stochastic dynamics of ten distinct MTJs. These devices exhibit an S-shaped switching probability as a function of the driving-voltage pulse width, thereby offering the essential nonlinearity, stochasticity, and tunability required for RC. Moreover, by adopting a time-division-multiplexing strategy that integrates outputs from all ten distinct devices, we implement a reservoir with enhanced dynamical diversity. The resulting system achieves an accuracy of over 96% on the Modified National Institute of Standards and Technology (MNIST) task and reduces the normalized root-mean-square error (NRMSE) of the nonlinear autoregressive moving average (NARMA-10) task by about 35% compared with the single-device case. In addition, the MTJs exhibit a 50% switching time of about 660 ps and the energy consumption per switching event is estimated to be about 17.6 fJ at 2 V and 150 kΩ. This study demonstrates the feasibility of using voltage-pulse-controlled MTJs for RC and provides a practical pathway toward hardware-based neural network implementations.

Anisotropy, arising from reduced symmetry in material systems, has significant implications for both fundamental science and technological applications. Despite its importance, fully understanding and harnessing anisotropy for controlling spin current generation in practical scenarios has been challenging. In this study, we introduce an approach to generate anisotropic spin current, using facet-controlled anisotropic energy densities in yttrium iron garnet (${\mathrm{Y}}_3{\mathrm{Fe}}_5{\mathrm{O}}_{12}$, YIG), through spin pumping and inverse spin Hall effect measurements. The cubic symmetry in YIG (001) generates a fourfold anisotropic spin current, which significantly influences spin pumping into the $\mathrm{Pt}$ layer. In contrast, the circular symmetry in YIG (111) results in an isotropic spin current. This leads to controlled anisotropic magnon transport, enabling the development of tunable magnonic devices and circuits.

Identification of neutron sources is central to nuclear physics and its applications, from planetary science to nuclear security, yet direct source discrimination from measured neutron spectra remains fundamentally elusive. Here, we introduce a Bayesian protocol that directly infers source ensembles from measured neutron spectra by combining full-spectrum template matching with probabilistic evidence evaluation. Applying this protocol to recoil and time-of-flight spectroscopy, we recover single- and two-source configurations with strong statistical significance (beyond $4\sigma$) at event counts as low as $\sim {10}^3$. These results demonstrate that neutron spectral signatures can be leveraged for robust source identification, opening a new observational window for both fundamental research and operationally driven applications.

Spectroscopic characterization is a key tool for determining carrier temperature in optoelectronic materials and devices. Assigning and extracting carrier temperature requires the assumption of quasiequilibrium, where carriers follow a Fermi-Dirac distribution. However, under low illumination intensities, carrier-carrier equilibration may be too slow for this assumption to hold. This is particularly relevant for hot carrier solar cells (HCSCs), which are required to operate under solar photon fluxes. Using a nonequilibrium model with a relaxation time approximation, we show that slow carrier-carrier scattering may distort temperature extraction from photoluminescence spectroscopy. Furthermore, our work shows that inefficient carrier-carrier equilibration in HCSCs leads to depletion of carriers at the extraction energies, resulting in a reduction in the extracted current and therefore the efficiency of the device. Our findings highlight the significance of considering carrier transport and scattering properties when evaluating and engineering candidate HCSC absorber materials.

The ingenious scheme we propose for achieving unidirectional reflection lasing (URL) onset involves integrating a one-dimensional defective atomic lattice with a coherent-gain atomic system. Its physical essence lies in the fact that the right-side reflectivity is drastically reduced due to the destructive interference between direct and secondary reflections, whereas on the left-side direct reflection is effectively suppressed and the secondary reflection is efficiently enhanced, ultimately reaching the lasing threshold. Through numerical results and further analyses, we have elucidated how to precisely tailor the lattice parameters and coupling fields to control the destructive-interference point, thereby enabling the onset and active modulation of URL. Our scheme not only effectively circumvents the stringent structural-parameter tuning process required to directly reach the URL onset, but also benefits the integration of active photonic devices into compact quantum networks and may improve the efficiency of optical information transmission.

A metamolecule comprising a metal double bar on a ferrite substrate exhibits nonreciprocal Fano resonance. A theoretical analysis demonstrates that the interaction between the two eigenmodes of the metamolecule depends linearly on the space- and time-inversion operations and the direction of the incident energy flow. Owing to these characteristics, the metamolecule exhibits nonreciprocal Fano resonance. Moreover, the difference in transmittance between forward and backward directions reaches the order of unity. Numerical and experimental studies confirm the theoretical findings. This study paves the way for realizing giant nonreciprocal Fano resonance with a single subwavelength structure.