We design a superconducting thermoelectric bolometer made of a graphene-insulator-superconductor tunnel junction. Our detector has the advantage of being passive, as it directly transduces input power to a voltage without the need to modulate an external bias. We characterize the device via numerical simulation of the full nonlinear thermal dynamical model of the junction, considering heating of both sides of the junction. While estimating noise contributions, we found expressions due to the temperatures of both sides being different from the bath temperature. Numerical simulations show a noise equivalent power of approximately $4\times {10}^{-17}\mathrm{W}/\sqrt{\mathrm{Hz}}$ for an input power of approximately ${10}^{-16}\mathrm{W}$, a response time of approximately $200\mathrm{ns}$, and an integration time to obtain a signal-to-noise ratio of 1 of approximately $100\text{μ}\mathrm{s}$ for an input power of approximately ${10}^{-13}\mathrm{W}$. Therefore, the device shows promise for large-array cosmological experiment applications, also considering its advantages for fabrication and heat budget.

Spin waves are attractive information carriers, owing to their gigahertz-to-terahertz frequencies, nanometric wavelengths, and negligible Joule heating. However, efficiently and locally exciting short-wavelength high-frequency propagating spin waves and exploiting nonlinear effects remain challenging. We propose a hybrid ferromagnetic structure consisting of an in-plane-magnetized nanosized area (a magnonic nanocavity) that is exchange-coupled to an out-of-plane-magnetized film or stripe. Micromagnetic simulations show that a spatially uniform out-of-plane microwave magnetic field excites only the fundamental mode of the nanocavity. Its second harmonic is then coherently and efficiently launched into the extended part of the ferromagnet, yielding propagating spin waves. This process can be achieved with stripe or extended film geometries, which excite plane waves or radial spin waves, respectively. Given the simple fabrication process of degrading the anisotropy of a ferromagnetic layer with perpendicular magnetic anisotropy, the spin-wave wave front can be shaped extensively by adjusting the nanocavity geometry. Conversion efficiency can be enhanced when the frequency of the second harmonic matches a higher-order standing spin-wave frequency of the nanocavity. Furthermore, the emission frequency is tunable via the bias magnetic field or the width of the nanocavity. These findings suggest a compact route toward on-chip, short-wavelength, high-frequency nonlinear spin-wave sources for artificial neural networks.

Weak measurement (WM) offers the advantage of amplifying small signals at the cost of postselecting a small portion of the probes. This so-called weak-value amplification effect makes it compare favorably with conventional techniques (without postselection) to overcome various technical noises. However, certain types of technical noise, such as jitter and pixelation, present insurmountable limitations for both WM and conventional techniques. In this work, we propose an advanced variant of WM that incorporates time-momentum correlation (TMC) into biased weak measurement (BWM). By employing the Fisher information metric, we theoretically show that TMC-BWM can overcome jitter and pixelation, and meanwhile extract significantly higher Fisher information. This dual advantage was experimentally validated in a magnetic-sensing application when applying severe jitter and pixelation, and it remains robust under natural conditions, achieving a 24.8-dB improvement in precision over the standard WM scheme. Moreover, merely classical resources are required to achieve this dual metrological advantage.

Inkjet printing is a highly reproducible and reliable droplet deposition technique. However, its stability can be compromised by the stochastic entrainment of an air bubble inside the ink channel, causing acute nozzle failure. Prior studies have linked bubble entrainment to the trapping of dirt particles, which are typically denser than the ink, inside the pulsating toroidal vortex formed above the jetting nozzle. While this seemingly counterintuitive trapping has been numerically studied in idealized unbound vortices, its behavior in realistic flows remains mostly unexplored. Here, we investigate particle trapping within a piezoacoustic inkjet channel by using two-phase flow simulations and by modeling particle translation using the Maxey-Riley equation. We compare two nozzle geometries, i.e., a straight nozzle and one tapered at ${10}^{\circ }$, and find that introducing this small taper significantly alters the oscillatory flow near the nozzle. For both nozzle types, particles in the relevant size range (4–8 $\text{μ}\mathrm{m}$) and particle-to-fluid density ratios (0.5–3) exhibit consistent trends: particles heavier than the fluid follow centripetal trajectories, spiraling inward within the vortex ring, while lighter particles follow centrifugal paths. Particles denser than the fluid can become trapped when the particles can no longer follow the high-frequency flow oscillations thereby limiting their kinetic energy, allowing the strong centripetal force from the pressure gradient in the vortex ring to pull them inward. The particle-trapping rate increases with both particle size and density ratio, and is similar for straight and tapered nozzles. However, in tapered nozzles, the vortex ring is smaller, resulting in fewer particles interacting with it, thereby reducing the number of particles trapped, and potentially mitigating dirt-induced bubble entrainment.

Droplet microfluidics combined with optical detection has emerged as a transformative avenue for high-throughput single-cell assays. However, these platforms often suffer from limited sensitivity and signal heterogeneity due to intrinsic optical and geometric constraints. We investigate how key operating parameters influence the performance of a droplet-based optomicrofluidic system. Our experiments probe optical interactions between guided light and aqueous droplets encapsulating fluorescent particles flowing in an oil medium. Geometric optics simulations model light-droplet interaction, while florescence simulations quantify signal variation due to particle size and position. Experimentally, we observe two refracted optical signals: a droplet-refracted signal that scales with droplet diameter, and a particle-refracted signal arising from light interaction with encapsulated particles. Both experiments and simulations reveal that the particle-refracted signal is prominent when the particle-to-droplet size ratio $D_{\mathrm{p}}^{\ast }$ is between 0.23 and 0.33, enabling label-free detection. Experiments also show that particles located near the droplet center ($r_{\mathrm{p}}^{\ast }<0.4$) exhibit a reduced angular dependence, producing more uniform fluorescence signals. Simulations indicate that the fluorescence intensity increases with $D_{\mathrm{p}}^{\ast }$, with a strong rise from 0.33 to 0.5 and a more gradual increase up to 0.66. Further, simulations show that reducing the thickness of the oil layer consistently increases fluorescence by minimizing optical losses at the droplet/channel interface. Our results demonstrate that controlling $D_{\mathrm{p}}^{\ast }$, particle position, and oil-layer thickness significantly increases fluorescence intensity and uniformity. These findings establish a quantitative and experimentally validated framework for optimizing droplet-based fluorescence detection, with potential applications in microflow cytometry and single-cell assays.

Elongate animals and robots use undulatory body waves to locomote through diverse environments. Geometric mechanics provides a framework to model and optimize such systems in highly damped environments, connecting a prescribed shape change pattern (gait) with locomotion displacement. However, the practical applicability of controlling compliant physical robots remains to be demonstrated. In this work, we develop a framework based on geometric mechanics to predict locomotor performance and search for optimal swimming strategies of compliant swimmers. We introduce a compliant extension of Purcell’s three-link swimmer by incorporating series-connected springs at the joints. Body dynamics are derived with the use of resistive force theory. Geometric mechanics is incorporated into movement prediction and into an optimization framework that identifies strategies for controlling compliant swimmers to achieve maximal displacement. We validate our framework on a physical cable-driven, three-link limbless robot and demonstrate accurate prediction and optimization of locomotor performance under varied programmed, state-dependent compliance in a granular medium. Our results establish a systematic, physics-based approach for modeling and controlling compliant swimming locomotion, highlighting compliance as a design feature that can be exploited for robust movement in both homogeneous and heterogeneous environments.

Guiding spin wave (SW) signals around turns in integrated magnonic circuits remains a challenge. Here, we calculated efficient SW transmission through Z-shaped turns of 120° using low-loss magnonic crystal (MC) waveguides comprising yttrium iron garnet (YIG) and a $\mathrm{Cu}$ hole array. The MCs were optimized using a finite integration technique, showing a complete magnonic band gap with a width of 15.1 MHz at a center frequency of 1.811 GHz. The MC waveguide showed 5.7 × ${10}^3$ times stronger SW propagation than ridge-type waveguides by avoiding SW depression caused by inhomogeneous internal magnetic field distributions in the YIG film. The effect of the bending radius on the SW propagation was evaluated through simulations. The proposed MC waveguide plays a vital role in SW waveguide integration by maintaining homogeneous magnetic field distributions throughout the unprocessed YIG film.

We report the fabrication of a barium magnesium fluoride (${\mathrm{Ba}\mathrm{Mg}\mathrm{F}}_4$) whispering-gallery-mode (WGM) microresonator demonstrating an intrinsic quality factor ($Q_0$) of about $2\times {10}^9$ at $1.55\text{μ}\mathrm{m}$, corresponding to a loaded quality factor ($Q_L$) of about $1\times {10}^9$ under critical coupling. At $398\mathrm{nm}$, the resonator exhibits a quality factor ($Q_L$) of $1.25\times {10}^8$ measured in the undercoupled regime, highlighting its potential for ultraviolet (UV) photonics. This performance was achieved in a 2.23-$\mathrm{mm}$-diameter resonator produced via a multistage process combining single-point diamond turning, chemomechanical polishing, and high-temperature annealing, yielding a surface roughness of approximately 1-$\mathrm{nm}$ RMS. Photoluminescence measurements under UV excitation revealed broadband visible emission, confirming the high optical quality of the crystal. When pumped in the near-infrared range, the resonator acted as a nonlinear element enabling the formation of Kerr optical frequency combs with a spectral width of about 30 nm and a line spacing of 42 GHz in the normal-dispersion regime. When incorporated into a fiber-laser cavity, it supported the generation of a frequency comb with a bandwidth of about 20 nm and a mode spacing of approximately 1 GHz at a pump power threshold of 86 mW. These results establish ${\mathrm{Ba}\mathrm{Mg}\mathrm{F}}_4$ WGM microresonators as a promising platform for nonlinear photonics across a broad spectral range, from the UV to the near-infrared.

Lowering the resource overhead needed to achieve fault-tolerant quantum computation is crucial to building scalable quantum computers. We show that adapting conventional maximum likelihood (ML) decoders to a small subset of efficiently learnable physical error characteristics can significantly improve the logical performance of a quantum error-correcting code. Specifically, we leverage error information obtained from efficient characterization methods based on cycle error reconstruction (CER), which yields Pauli error rates on the $n$ qubits of an error-correcting code. Although the total number of Pauli error rates needed to describe a general noise process is exponentially large in $n$, we show that only a few of the largest few Pauli error rates are needed and that a heuristic technique can complete the Pauli error distribution for ML decoding from this restricted dataset. Using these techniques, we demonstrate significant performance improvements for decoding quantum codes under a variety of physically relevant error models. For instance, with CER data that constitute merely 1% of the Pauli error rates in the system, we achieve a 10 times gain in performance compared with the case where decoding is based solely on the fidelity of the underlying noise process. Our conclusions underscore the promise of recent error characterization methods for improving quantum error correction and lowering overheads.

We present a differential technique for vector magnetic sensing based on a cold-atom cloud in a magnetic quadrupole trap. An external homogeneous magnetic field displaces the trap center in a direction and with a magnitude proportional to the field. By reversing the quadrupole polarity between experimental shots and comparing the resulting cloud positions, we extract a differential displacement signal that is free from common-mode effects such as gravity and weak magnetic field inhomogeneities. The signal is directionally proportional to the external field and requires only absorption imaging, without spectroscopic interrogation. Assuming micron-scale position resolution, the technique enables field resolution at the milligauss level. It offers a practical tool for field compensation in magnetically sensitive experimental stages, bridging operational regimes from Earth-level fields to atomic magnetometry. A straightforward extension to full three-dimensional sensing is possible with only a minimal addition to standard cold-atom infrastructure.

Laser-generated surface acoustic waves (SAWs) facilitate efficient information processing in modern spintronics and magnonics. The ability to tune the SAW parameters such as the amplitude is crucial to achieve acoustic control over magnonic properties. Such tunability can be achieved in phase-changing magnetic materials that accommodate both spin waves and SAWs. A promising material is the $\mathrm{Fe}$-$\mathrm{Rh}$ alloy, a metallic antiferromagnet at room temperature that undergoes a phase transition to the ferromagnetic state accompanied by a crystal lattice expansion at 370 K. This transition can also be induced by femtosecond laser pulses. In this paper, we use the phase transition in a 60-nm $\mathrm{Fe}$${}_{49}$$\mathrm{Rh}$${}_{51}$ film to optically generate pulses of Gigahertz quasi-Rayleigh SAWs. We detect them via the photoelastic effect and show that the lattice transformation during the phase transition is a dominant strain-generation mechanism for above-threshold excitation. The weight of this contribution rises as the sample is heated closer to the antiferromagnetic-ferromagnetic transition temperature and “switches off” when heated above it, allowing for control of the SAW amplitude. A model based on thermodynamic parameters of $\mathrm{Fe}$${}_{49}$$\mathrm{Rh}$${}_{51}$ shows that the lattice transformation occurring within 95 ps effectively contributes to SAW generation happening on a comparable timescale, while nonequilibrium fast kinetics of the phase transition does not.

Point defects, including intentional dopants, compensating impurities, and native point defects, as well as extended defects have a large impact on semiconductor devices and their performance. Some point defects are intentionally incorporated as dopants to provide free carriers or intentionally compensate material, and others serve as nonradiative and scattering centers that are deleterious to device performance. Shockley-Read-Hall (SRH) recombination is commonly used to determine the recombination rate associated with point defects when simulating devices. As the SRH model was developed treating only the capture processes of carriers with defects that scale linearly with carrier density, such as multiphonon emission and radiative capture, the defect-mediated recombination rates and currents it predicts are accurate only in the low-carrier-density regimes. Our recent experimental observation of hot electrons generated by trap-assisted Auger-Meitner recombination (TAAR) from a shallow impurity [Phys. Rev. B 111, 155308 (2025)], whose emission currents had a strong dependence on the operating device currents, raises a question regarding whether only a single type of capture and emission process can be ascribed to a given defect, or instead if several possible capture and emission processes with an appreciable rate must be considered for the same defect. In this work, we extend the conventional SRH analysis to include trap-assisted Auger-Meitner processes in defect-assisted recombination cycles (DARCs). The inclusion of TAAR processes in DARCs demonstrates that defect-mediated recombination rates and currents can scale quadratically with carrier density and can significantly deviate from the predictions of the conventional SRH model, especially in the higher-carrier-density regimes. We perform a case study for the recombination rates involving the ${\mathrm{Ca}}_{\mathrm{Ga}}$ impurities in $\mathrm{Ga}\mathrm{N}$ using our formalism, where ${\mathrm{Ca}}_{\mathrm{Ga}}$ is chosen because hot electrons from ee TAAR involving ${\mathrm{Ca}}_{\mathrm{Ga}}$ have been measured using electron emission spectroscopy. Implementation of DARCs using the analytical framework presented in this article can result in the increased accuracy of simulated defect-mediated recombination rates, especially for situations where there are large excess carrier densities such as in quantum-well-based light-emitting diodes and lasers.

Artificial atoms nonlocally coupled to waveguides—the so-called giant atoms—offer opportunities for the control of light and matter. In this work, we show how to use an array of nonlocally coupled transmon “molecules” to engineer a passive photonic controlled gate for waveguide photons. In particular, we show that a conditional elastic phase shift between counterpropagating photons arises from the interplay between direction-dependent couplings, engineered through an interplay of nonlocal interactions and molecular binding strength; and the nonlinearity of the transmon array. We analyze the conditions under which a maximal $\pi$-phase shift—and hence a CZ gate—is obtained, and characterize the gate fidelity as a function of key experimental parameters, including finite transmon nonlinearities, emitter spectral inhomogeneities, and limited cooperativity. Our work opens the use of giant atoms as key elements of microwave photonic quantum computing devices.

In recent years, multilayer structures that tune topological phases through the regulation of the layer degree of freedom have attracted significant attention. Compared with monolayer systems, multilayer systems with interlayer coupling can host a richer variety of topological phases, among which those with heterogeneous layers remain insufficiently explored. In this paper, based on the two-dimensional Su-Schrieffer-Heeger model, we investigate bilayer and trilayer heterostructures composed of vertically stacked layers with different topological properties. We find that variations in the interlayer coupling strength can induce topological phase transitions in the system, significantly altering the number of corner states in these topological structures. The evolution of the number of corner states is further directly demonstrated by calculating the multipole chiral numbers. We performed acoustic simulations to verify the variation in the number of corner states in bilayer and trilayer heterostructures, and further proposed a new scheme for constructing topological bound states in the continuum. Our work experimentally demonstrates the effectiveness of this phenomenon in acoustic systems and offers a practical route to realize reconfigurable acoustic devices for wave-energy confinement, topological filtering, and sensing, leveraging controllable layer coupling in compact architectures.

Retrieving information through disordered scattering systems remains a major challenge in wireless communication and sensing due to the severe distortion and attenuation caused by multiple scattering. Here, we demonstrate robust focusing through random media using a leaky cavity made programmable by reconfigurable metasurfaces. We show that the leaky cavity leverages backscattering from the disordered medium to enhance the degree of control over the transmitted field. We achieve an enhancement in focused intensity by an order of magnitude compared to that of a horn antenna. We further demonstrate robust communication through the medium using low-power amplitude-modulated signals and finally implement a backscatter communication scheme in which the same cavity illuminates and decodes data from a passive reflectivity-modulating target embedded within the disorder. Our results highlight the potential for reliable communication and sensing in complex environments.