Superconducting quantum interference devices (SQUIDs), formed by incorporating Josephson junctions into loops of superconducting material, are the backbone of many modern quantum sensing systems. It has been demonstrated that, by combining multiple SQUID loops into a two-dimensional (2D) array, it is possible to fabricate ultrahigh-performing radio-frequency sensors. However, to function as absolute magnetometers, current-in-use arrays require the area of each SQUID loop in the array to be incommensurate. In doing so forbids the achievement of their full potential of performance, limited only by the standard quantum limit. This is because imposing incommensurability in the areas contrasts with optimized performance in each single SQUID loop. In this work, we report that by selectively inserting “bare” sections of a superconducting circuit with no Josephson junctions, 2D SQUID arrays can operate as an absolute magnetometer even when no physical area spread is applied. Based on a generalization of currently available theories, a complete analytical formulation for the one-to-one correspondence between the distribution of these bare loops and what we call a “synthetic area spread” is unveiled. This synthetic spread represents the equivalent physical spread of incommensurate SQUID loops that you would use to obtain the absolute voltage-magnetic flux response if no bare loops were in use. Our work opens the way to a broader use of this technology for the fabrication of ultrahigh-performance absolute quantum sensors. Our approach is also experimentally verified by fabricating several 2D superconducting quantum interference filter arrays incorporating bare superconducting loops and by demonstrating that they behave in alignment with what is suggested by our theory.

Focused helium ion beam (He-FIB) irradiation with 30-keV ions is a key tool for nanoscale patterning and defect engineering in high-transition temperature ($T_{\mathrm{c}}$) cuprate superconducting devices, yet its usable fluence window is constrained by the competing requirements of reliable superconductivity suppression and minimal structural degradation. In this work, we provide a comprehensive dataset on the effects of large-area 30-keV ${\text{He}}^{+}$ ion exposure on the electric transport and superconducting properties of epitaxial ${{\mathrm{YBa}}_2{\mathrm{Cu}}_3\mathrm{O}}_{7-\delta }$ (YBCO) thin films. X-ray diffraction shows a fluence-driven loss of crystalline order accompanied by an out-of-plane lattice expansion and an orthorhombic-to-tetragonal transition, culminating in predominant amorphization at the highest fluence of $1\times {10}^{16}{\mathrm{cm}}^{-2}$. Raman spectra exhibit increasing disorder while lacking signatures of oxygen depletion, indicating that irradiation mainly generates oxygen-related Frenkel defects rather than changing the carrier concentration. Consistently, with increasing fluence, the normal-state resistivity ${\rho }_{\mathrm{N}}(T)$ at temperature $T$ above $T_{\mathrm{c}}$ increases strongly, while $\partial {\rho }_{\mathrm{N}}/\partial T$ remains nearly unchanged at moderate fluence. The suppression of $T_{\mathrm{c}}$ is accurately described by Abrikosov–Gor’kov pair breaking and reaches complete quenching of superconductivity at $4.5\times {10}^{15}{\mathrm{cm}}^{-2}$. The anisotropic upper critical fields decrease approximately exponentially with increasing fluence; the vortex activation energy is reduced, and the anisotropy drops, in contrast to oxygen-depleted YBCO. Hall-angle analysis confirms a nearly constant carrier density but a systematic increase in defect scattering and reduced mobility, consistent with a crossover toward the dirty limit at high fluence. These results establish quantitative fluence thresholds and a practical operational window for He-FIB nanopatterning of YBCO quantum circuits.

Topologically nontrivial magnetic textures such as skyrmions offer promising opportunities for spintronic applications. In recent years, it has been shown that the magnetic properties of layered materials can be affected by depositing chiral molecules on the surface, while the influence of chiral overlayers on skyrmion properties such as their stability and interactions remains largely unexplored. To address this challenge, we employ wide-field nitrogen-vacancy ($\text{N}\text{−}V$) magnetometry to directly image skyrmions in chiral-molecule-functionalized magnetic thin films, enabling quantitative mapping of magnetic stray fields over extended areas under ambient conditions. Using pixel-resolved optically detected magnetic resonance (ODMR) combined with controlled magnetic fields, we reproducibly nucleate and probe skyrmion states in CoFeB ferromagnetic samples, enabling quantitative investigation of their properties. We observe indications of enantioselective and magnetic-field-polarity-dependent modifications of skyrmion properties suggesting possible chirality-dependent modifications of topological spin textures and motivating future theoretical investigations of the underlying coupling mechanisms.

We present experimental evidence of a thermally driven amplitude-frequency nonlinearity in a thin-film quartz phononic crystal resonator at millikelvin temperatures. The nonlinear response arises from the coupling of the mechanical mode to an ensemble of microscopic two-level system (TLS) defects driven out of equilibrium by the microwave readout signal. In contrast to the conventional Duffing oscillator, the observed nonlinearity exhibits a mixed reactive-dissipative character. Notably, the reactive effect can manifest as either a softening or hardening of the mechanical resonance, depending on the ratio of thermal to phonon energy. By combining the standard TLS theory with a thermal conductance model, the measured power-dependent response is quantitatively reproduced, and readout-enhanced relaxation damping from off-resonant TLSs is identified as the primary mechanism limiting mechanical coherence. Within this framework, we delineate the conditions under which similar systems will realize this nonlinearity.

Optical forces in focused-beam traps are generally nonconservative, yet the controlled use of this nonconservative component for airborne single-particle dynamics remains limited. We demonstrate a dual-beam optical trap in which a single aerosol can be switched between localized confinement and sustained orbital motion by tuning the relative positions of two counter-propagating foci. The axial separation $\mathrm{\Delta }D$ controls the onset of nonconservative circulation, while the lateral offset $\mathrm{\Delta }R$ tunes the projected orbit size and causes a monotonic change in the rotation frequency. T-matrix optical force calculations and Langevin simulations support this interpretation by showing that finite axial misalignment activates a circulating force component, whereas near-zero axial separation gives a confinement-dominated force field. Experiments confirm the predicted switching behavior through mean-square displacement and frequency measurements. We further show that the projected orbit geometry provides a particle-dependent observable, with the orbit anisotropy $A_y/A_x$ varying systematically with aerosol diameter. The results provide a compact, low-power platform for controlled orbital dynamics of single airborne particles and for future aerosol measurements based on nonequilibrium trajectory observables.

Decoherence remains a critical obstacle to achieving high-fidelity, scalable superconducting qubits, with the tunnel barrier of Josephson junctions a key source of loss, yet the microscopic structure of this buried layer has remained difficult to probe experimentally. Here, we use resonant x-ray reflectivity to resolve the coordination environments within the ${\text{AlO}}_x$ barrier of $\text{Al}/{\text{AlO}}_x/\text{Al}$ Josephson junctions as a function of oxidation conditions. We find that the barrier coordination evolves from more tetrahedral toward octahedral character with increasing oxidation pressure, while the lower metal-oxide interface is comparatively undercoordinated and disordered relative to the upper interface. Comparison with simulated x-ray absorption spectra identifies the dominant coordination motifs within the oxide and at its interfaces, providing depth-resolved structural insight that informs microscopic models of two-level system formation. These results link growth conditions, local coordination environments, and junction electronic properties, providing a materials-level foundation for interpreting how the tunnel barrier influences coherence in superconducting qubits.

Gate geometry and bias asymmetry can be used to engineer spin dynamics in gate-defined Ge hole quantum dots by reshaping the confinement potential and driving transitions between distinct confinement regimes. Using a realistic three-dimensional device model, we show that these transitions strongly modify wave function localization, heavy-hole/light-hole mixing, and the effective vertical electric field, leading to pronounced $g$-factor modulation and geometry-induced dephasing sweet spots where the qubit becomes first-order insensitive to vertical electric-field fluctuations. We further find that phonon-induced spin relaxation exhibits a strong dependence on device size and bias, with $T_1$ following a magnetic-field scaling close to $B^{-9}$, consistent with Rashba-dominated heavy-hole spin dynamics. Our results establish gate pattern and bias design as practical tools for optimizing spin coherence in Ge hole-spin qubits.

We present an analytical framework capable of describing spin-wave dynamics in magnetic heterostructures composed of a pair of exchange-decoupled magnetic layers separated by a nonmagnetic spacer, focusing in particular on garnet-based multilayers. The model captures the formation of collective spin-wave modes, namely symmetric and antisymmetric, arising from dipolar coupling and provides direct access to the dispersion relation of the system and consequent interference phenomena. This formalism establishes a versatile theoretical tool for the predictive design of dipolarly coupled magnonic devices, providing access to their eigenfrequencies and mode shapes.

The optoelectronic heterojunction devices are one of the hot research topics for realizing artificial vision bionics. However, simultaneously achieving nonvolatile storage, monolithic scalability, and long-term stability remains a significant challenge. Here, we propose an artificial optoelectronic synaptic device based on the AlSb/Al(As, Sb) and InAs/In(As, Sb) superlattice (SL) heterojunctions, which can integrate sensing and storage functions. By employing the strain-compensated molecular beam epitaxy technique, a barrier SL heterostructure introducing localized trap centers was constructed. This architecture efficiently regulates transport carriers under the stimulation of visible light (405 nm), leading to long-term persistent photoconductivity. The device displays biological synaptic functions, including short- and long-term plasticity, paired-pulse facilitation (PPF), and learning-experience behaviors similar to those of human beings. Especially, it demonstrates a high PPF index of 138% and favorable process compatibility. Furthermore, we fabricated a $5\times 5$ optoelectronic synaptic array and successfully demonstrated the processes of visual imaging and memory functions, as well as neuromorphic visual preprocessing with improved processing efficiency and accuracy in subsequent image recognition tasks. This work underscores the potential of III–V SL heterostructures as a scalable platform for next-generation biomimetic visual perception systems.

Transmitter-side device dependence is a longstanding yet implicit problem in quantum key distribution (QKD), in contrast to the thoroughly addressed measurement-side case. Quantum steering, which intrinsically distinguishes the roles of sender and receiver in entanglement certification, offers a natural route to lifting trust assumptions on the transmitter. Existing one-sided device-independent (1sDI) protocols that exploit quantum steering as the security resource typically operate in a tripartite architecture, whereas adapting them to a transmitter-receiver architecture can introduce a signaling loophole. Here we conceptually formalize the transmitter-device-independence on the basis of faithful quantum steering and propose a practical transmitter-device-independent (TDI) QKD protocol within the 1sDI trust model. The TDI scheme operationalizes the implicit no-signaling condition by enforcing a causal isolation between the input information and the transmitted quantum states, thereby eliminating the associated transmitter-side device vulnerabilities. In a proof-of-principle experiment, we validate the feasibility of the TDI protocol, achieving a key rate in the asymptotic limit of 410 bps over 27 km spool fiber. By delivering TDI security while retaining strong loss tolerance, our approach helps bridge the gap between security and practicality for real-world QKD deployments.

We develop a differential source-pattern protocol for local displacement estimation in a time-reversed Young interferometer, where the source plane is used not merely as a scan coordinate but as a programmable measurement pattern. A signed antisymmetric pattern is implemented by two sequential positive-only source branches, as required by intensity-only source hardware, and the two branch counts are retained as the complete measurement record. Near a quadrature operating point, the local differential signal separates into an envelope-gradient term and a time-reversed-Young interference-gradient term. We connect the localized response kernel to a concrete scanned-excitation measurement of a displaced fluorescent, quantum-dot, or transmissive microfeature and give a representative experimental parameter set. We distinguish the exact finite-spacing response from its derivative approximation, enforce an equal launched-photon budget in all comparisons, and derive the Fisher information both for the full Poisson count pair and for the scalar difference, which follows a Skellam distribution. The numerical results show a clear advantage over a fixed raster sample in the representative regime, while the additional interferometric contribution can enhance, leave unchanged, or suppress the information relative to a matched noninterferometric differential measurement. An optimized direct measurement remains the stronger ideal benchmark when all nuisance quantities are known. The results therefore establish practical design rules for robust local displacement metrology rather than a universal claim of two-feature superresolution.

In contrast to hafnia (${\text{HfO}}_2$) thin films, where the appearance of switchable ferroelectric polarization can be induced by strain or defect engineering, reliable methods for controlling ferroelectricity in ${\text{HfO}}_2$ nanoparticles are absent. Direct experimental observations of ferroelectric hysteresis and ferroelectric domains in these nanoparticles have also not been reported. To the best of our knowledge, stress-induced ferroelectric states in the ${\text{HfO}}_2$ nanoparticles have not been explored. In this work, we study the influence of chemical stress on phase diagrams, dielectric properties, and polar properties of spherical ${\text{HfO}}_2$ core-shell nanoparticles using a Landau-Ginzburg-Devonshire free energy functional that includes trilinear and biquadratic couplings involving polar, antipolar, and nonpolar order parameters. The ferroelectric phase exhibits reentrant behavior as a function of nanoparticle size, such that the spontaneous polarization exists only within a limited range of core radii $R_c$, namely $R_{\mathrm{cr}}^{\min }<R_c<R_{\mathrm{cr}}^{\max }$. The minimal critical radius $R_{\mathrm{cr}}^{\min }$ is primarily determined by the size dependence of the depolarization field and correlation effects, whereas the maximal critical radius $R_{\mathrm{cr}}^{\max }$ is governed mainly by the size dependence of chemical stresses induced by the elastic defects in the shell. Thus, this work identifies a stress-driven mechanism for reentrant ferroelectricity stabilization in nanoscale hafnia systems, arising from the competition between depolarization field-induced suppression of ferroelectricity and its stabilization by shell-induced chemical stress. We revealed that relatively large compressive chemical strains are necessary to induce the ferroelectric phase in the ${\text{HfO}}_2$ nanoparticles. Successful chemical strain engineering opens the way for significant enhancement of nanoscale ${\text{HfO}}_2$ polar properties for applications in advanced memory cells and logic devices.

The development of a highly efficient electrocatalyst for the hydrogen-evolution reaction (HER) plays a vital role in the process of water splitting. Two-dimensional (2D) materials are crucial for the HER due to having a large surface-to-volume ratio, tunable electronic properties, and abundant active sites, which collectively enhance their catalytic efficiency and lower the energy barriers for hydrogen production. Boron oxide (BO) is a recently synthesized light-elements-based 2D material that has not been extensively studied yet. The present work delves into the catalytic performance of pristine and single transition metal-decorated BO monolayer (TM@BO, TM = Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Y, Zr, Mo, Ru, Rh, Pd, Ag, Ir, Pt, or Au) for the HER using first-principles density functional theory calculations. The pristine BO monolayer exhibits an indirect band gap with a larger value of Gibbs’ free energy change $\mathrm{\Delta }G=2.33\mathrm{eV}$ as compared with the expected value for an efficient catalyst ($\mathrm{\Delta }G\sim 0\mathrm{eV}$). In contrast, Ti@BO and Fe@BO monolayers exhibit excellent HER performance with extremely low overpotential values around $-0.04\mathrm{eV}$ and 0.004 eV, respectively. The thermal stability of the Ti@BO and Fe@BO systems is confirmed through the AIMD simulations with minimal changes in the bond length and energy. The charge density difference and Bader charge analysis indicate a strong interaction of Ti and Fe on BO due to charge transfer from the metal d orbital to the 2p orbital of oxygen. The room-temperature electron mobility of the Ti@BO exhibits significant enhancement around ($52.96\times {10}^4{\mathrm{cm}}^2{\mathrm{V}}^{-1}{\mathrm{s}}^{-1}$). The study of the reaction mechanism through the climbing image nudged elastic band method using the Volmer, Heyrovsky, and Tafel scheme under acidic and alkaline media shows that the Volmer–Heyrovsky reaction is the dominant mechanism for both the Fe@BO and Ti@BO monolayers, with the Volmer mechanism as the rate-determining step. However, under an alkaline medium, the HER process is less favorable due to the presence of large energy barriers. Our calculations predict a promising single-atom catalyst-based BO monolayer, which can be useful for its device application in energy conversion and storage.

We investigate the differential voltage generation originating from the direct magnetoelectric effect in nanoscale composite devices during magnetization rotation from the magnetic ground state to an out-of-plane configuration. The devices consist of a magnetostrictive ferromagnetic layer mechanically coupled to a piezoelectric layer. Using finite-element modeling in comsol Multiphysics, we systematically analyze strain transfer mechanisms and the resulting open-circuit voltage generation as a function of material and geometric parameters. At nanoscale dimensions, two distinct strain transfer regimes emerge, with the dominant mechanism governed by both device aspect ratio and magnetic state. Surface clamping effects are found to diminish with decreasing pillar diameter and increasing aspect ratio, while strain transfer to the piezoelectric layer is enhanced by stiffer electrodes or additional clamping layers. Furthermore, magnetostrictive materials with large magnetoelastic coupling and high Poisson ratio substantially increase the voltage output at small dimensions. These results provide design guidelines for material selection and dimensional scaling of magnetoelectric pillars. Output voltages exceeding 200 mV are predicted for scaled devices, highlighting their potential for integration in microelectronic applications.

Achieving broadband sound manipulation within deep-subwavelength, ventilated structures remains a fundamental challenge in acoustics. Here, we introduce a degenerate sandwich architecture that exploits the synergistic coupling of monopoles and dipoles. This platform enables simultaneous broadband control over sound reflection, transmission, and absorption. We experimentally validate this concept using a sandwich-structured device comprising two Fabry-Pérot resonator arrays and a central microperforated plate. Remarkably, featuring a deeply subwavelength cumulative interaction length of merely $\lambda /107$ at 200 Hz, the device achieves near-perfect sound absorption (99%) across an ultrawide spectrum of 200–2000 Hz. Furthermore, the device provides robust sound insulation that significantly outperforms conventional mass-law predictions while maintaining permissible airflow. The industrial viability of this strategy is practically demonstrated through a prototype silencer for a household vacuum cleaner. This work overcomes inherent bandwidth limitations in subwavelength wave manipulation and paves the way for advanced noise-control technologies in open systems.

The adaptive oscillator itself is capable of a type innate neuromorphic processing, as it can dynamically learn and store information about an external signal. When used as a physical reservoir computer, it has been demonstrated that the adaptive oscillator possesses both self-learning and the ability to be used as a multiplex-free morphable logic gate. In addition to these useful traits, the Duffing adaptive oscillator is also a physical unclonable function. Here, a bifurcation diagram is proposed as a novel challenge-response pair. Notably, since the bifurcation diagram is asymptotically approached by the oscillator’s dynamics, it is easily reproducible. Further, small changes to the oscillator’s parameters produce large changes to the bifurcation diagram, which makes it act as a “fingerprint” of the oscillator. From an applied perspective, this means that the Duffing adaptive oscillator could be implemented as a trusted artificial intelligence hardware device.

Exploring the synergy between topological physics and nonlinear dynamics unveils profound insights into emergent states of matter. Inspired by recent experimental demonstrations of topological frequency combs in photonics, we theoretically introduce topological magnon frequency combs (MFCs) in a two-dimensional triangular skyrmion lattice. Computing the Chern numbers of magnon bands reveals robust chiral edge states. The nonlinear four-magnon scattering among the chiral edge modes generates the topological MFCs, activated by dual-frequency microwave driving without an amplitude threshold. The comb spacing is readily tunable through excitation frequency detuning. We finally show that the proposed topological MFCs are robust against disorder, bulk leakage, and thermal fluctuations, although strong nonlinearity exists. This work paves the way for defect-immune magnonic devices exploiting MFCs and sparks investigations into topological-nonlinear phenomena in magnetic systems.

Hole spin qubits based on semiconductor quantum dots are promising for building future large-scale quantum computers owing to their all-electrical manipulation. However, abundant physical mechanisms of valence-band holes lead to anisotropic qubit properties. There is an opportunity to prolong the coherence time and achieve high-fidelity qubit manipulations. Here, we report a single-hole spin qubit in a planar germanium quantum dot and investigate its anisotropic susceptibility to charge noise under an in-plane magnetic field. By correlating the longitudinal spin-electric susceptibility with qubit coherence and control performance, we identify an optimal operating point where the sensitivity to charge noise is minimized. We find that optimizing the magnetic-field orientation reduces the spin-electric susceptibility, resulting in a fivefold enhancement of the Hahn-echo coherence time and a nearly tenfold suppression of control infidelity. At the optimal operating point, gate set tomography demonstrates the maximum gate fidelity of 99.82%. Our finding enhances the prospects of hole spin qubits for scalable quantum information processing.