Photonic crystal (PhC) nanocavities, which offer ultimate light confinement in both time and space, play an indispensable role in enhancing light-matter interactions. They provide an effective pathway to study solid-state quantum photonics with embedded quantum dots (QDs). However, during the nanocavity design, the balance between the QD and cavity performance is rarely considered. Here, we propose an $\mathrm{H}0/1$ photonic crystal cavity by introducing an additional air hole at the center of an H0-type cavity. Using automated optimization based on the covariance matrix adaptation evolution strategy, the cavity simultaneously achieves a high quality factor $Q$ of approximately ${10}^6$ and a small mode volume ($V$) of $0.317(\lambda /n{)}^3$, while preserving a sufficiently large effective dielectric area that is essential to achieve high spatial field-QD overlap and maintain the exciton coherence of the QD theoretically. The Purcell enhancement of a single QD in the $\mathrm{H}0/1$ cavity is realized experimentally. Compared with cavities possessing a single field maximum, the high-$Q$ low-$V$ $\mathrm{H}0/1$ cavity mode supports two spatially separated field maxima. It enables cavity-mediated collective interactions between distinct QDs when taking full advantage of the extremely strong light confinement capability. The potential of the proposed design for studying superradiance and subradiance is further discussed, offering a platform for quantum information applications.

Strong coupling in wave-based systems often causes level repulsion, leading to mode splitting and reduced response at the target frequency. This problem is pronounced in magnetic resonance imaging, where strong mutual inductance between a receive coil (RC) and a metamaterial (MM) degrades $B_1$ performance. Here, we introduce a non-Hermitian complex-coupling decoupling strategy based on a dual-resonator model. By engineering a phase delay in the coupling pathway, an imaginary coupling component is created, driving the system from the PT-symmetric to the anti-PT-symmetric phase and enabling eigenmode degeneracy without added dissipation. Implemented through a high-permittivity ceramic layer, this mechanism restores single-mode resonance in the MM-RC system and suppresses frequency splitting. Simulations indicate that the proposed strategy substantially mitigates the severe $B_1$ degradation in the strongly repulsive regime. The recovered $B_1$ efficiency corresponds to an approximately 14-fold increase relative to that worst-case condition, and to an approximately 1.4-fold enhancement relative to the standalone birdcage coil. This passive, compact, and hardware-compatible approach offers a general route for coupling control in electromagnetic, acoustic, optical, and quantum systems.

We report the experimental control of Floquet magnons in a magnetic vortex. Using microwave spectroscopy of vortex-state magnetic tunnel junctions, we find that self-induced Floquet sidebands form frequency combs whose existence depends on the vortex core orbit. By shifting the vortex core with an applied magnetic field, we switch the system between regular and Floquet magnons at identical drive conditions, demonstrating hysteretic control of the Floquet spectrum. A nonlinear vortex-magnon model shows that this behavior originates from multiple stable vortex gyration radii created by Floquet-mediated feedback. These results establish magnetic state initialization as a means to switch between regular and Floquet magnons.

Monolithic three-dimensional (3D) Paul traps combine the high-precision microfabrication of two-dimensional (2D) chip traps with the deep trapping potentials and low heating rates characteristic of macroscopic 3D Paul traps, which are typically machined by traditional means and mechanically assembled. However, achieving low motional heating rates and optical access with a high numerical aperture (NA) while maintaining the high radio-frequency (rf) voltages required for trapping heavy ionic species, such as ${\text{Yb}}^{+}$ and ${\text{Ba}}^{+}$, remains a significant technical challenge. In this work, we present a fused silica, monolithic segmented 3D Paul trap with an ion-electrode distance of $250\mathrm{\mu }\mathrm{m}$, and stable operation at high rf voltages. We benchmark the trap’s performance using ${\text{Yb}}^{+}$ ions, demonstrating axially homogeneous trapping potentials spanning over $200\mathrm{\mu }\mathrm{m}$ about the trap’s axial center, high multidirectional optical access (up to 0.7 NA), and radial motional heating as low as $\dot{\overline{n}}=1.1\pm 0.1\mathrm{quanta}/\mathrm{s}$ at radial trap frequencies about $3\mathrm{MHz}$ near room temperature. Furthermore, we observe a motional Ramsey coherence time, $T_2$, of about $96\mathrm{ms}$ for the radial center-of-mass mode. We demonstrate the generation of a two-qubit Bell state with a parity contrast of ${99.3}_{-1.5}^{+0.7}\%$ with state preparation and measurement correction. These results establish fused-silica monolithic 3D Paul traps as a scalable, modular platform for quantum simulation, computation, metrology, and networking with heavy ionic species.

Scalable, high-fidelity quantum-state readout remains a central challenge in the development of large-scale superconducting quantum processors. Conventional dispersive readout architectures depend on bulky isolators and external amplifiers, introducing significant hardware overhead and limiting opportunities for on-chip information processing. In this work, we propose an approach that embeds a superconducting nonlinear asymmetric inductive element (SNAIL) into the readout chain, enabling coherent and directional processing of readout signals directly on-chip. This embedded SNAIL platform allows frequency-multiplexed resonators to interact through engineered couplings, forming a tunable readout-amplifier-output architecture that can manipulate quantum readout data in situ. Through theoretical modeling and numerical optimization, we show that this platform enhances fidelity, suppresses measurement-induced decoherence, and simplifies hardware complexity. These results establish the hybridized SNAIL as a promising building block for scalable and coherent quantum-state readout in next-generation processors.

Hong-Ou-Mandel (HOM) interference offers robustness in high-noise environments due to its phase-insensitive nature, while N00N-state interference provides enhanced phase sensitivity for precision measurements in low-noise settings. However, their realizations have typically required separate experimental platforms. Here, we report a single hybrid quantum interferometer that can dynamically transition between HOM and N00N-state interference by adjusting two time delays, ${\tau }_1$ and ${\tau }_2$. This tunability enables operation in phase-insensitive, phase-sensitive, or hybrid modes within a unified setup, as confirmed by theoretical analysis and experimental demonstration. Our system offers a versatile platform with potential for quantum sensing applications, paving the way for integrated quantum technologies capable of adapting to diverse noise conditions.

The short quantum link regime, where the photon travel time $\tau$ is comparable to the emitter lifetime $1/\gamma$, is experimentally relevant but theoretically underexplored: existing few-mode descriptions lose validity as retardation and multimode effects become significant. Using a delay differential equation (DDE) framework that admits exact analytical solutions from the single-mode cavity limit to the multimode waveguide continuum, we show that emitters coupled to a short link spontaneously lock into self-synchronized Rabi oscillations driven by coherent photon echoes, breaking the link’s discrete time-displacement symmetry. The resulting spectral structure—persistent quasidark states and vacuum Rabi splitting, including in the superstrong coupling regime—enables efficient quantum state transfer (QST): benchmarking three protocols across the full $\gamma \tau$ parameter space, we find that STIRAP exploits the quasi-dark-state structure to achieve a quadratic infidelity floor $\mathcal{O}[(\gamma \tau {)}^2]$, outperforming both SWAP (linear error $\mathcal{O}(\gamma \tau )$) and wave-packet engineering for $\gamma \tau \lesssim 1.44$, even in regimes where retardation cannot be neglected. These results establish photon-echo synchronization as an engineering resource for quantum state transfer, with DDE modeling providing the exact analytical predictions needed to design and optimize short-link experiments on current circuit-QED hardware.

Conventional optical materials are characterized by either a dissipative response, which results in polarization-independent absorption, or by a gain response that leads to wave amplification. In this work, we study a peculiar class of materials with chiral-gain properties, where gain selectively amplifies waves of one polarization handedness, while dissipation suppresses the opposite handedness. We uncover a novel phenomenon, “gain-momentum locking,” at the boundary of chiral-gain media, where surface plasmons are amplified or attenuated based on their direction of propagation. This effect, driven by the interplay between spin-momentum locking and polarization-sensitive non-Hermitian responses, enables precise control over unidirectional wave propagation. Our findings open the door to the design of unidirectional photonic devices with compensated attenuation and the generation of light with intrinsic orbital angular momentum.

With a growing interest in securing user data within the internet of things (IoT), embedded encryption has become of paramount importance, requiring light-weight high-quality random-number generators (RNGs). Emerging stochastic device technologies produce random numbers from stochastic physical processes at high quality; however, their generated random-number streams are adversely affected by process and supply-voltage variations, which can lead to bias in the generated streams. In this work, we present an adaptive variation-resilient RNG capable of extracting unbiased encryption-grade random-number streams from physically driven entropy sources, for embedded cryptography applications. The system’s key feature is its adaptive digitizer with an adaptive reference voltage. As a proof of concept, we employ a stochastic magnetic tunnel junction (sMTJ) device as an entropy source. The impact of variations in the sMTJ is mitigated by the adaptive digitizer, which generates an adaptive short-term average reference voltage that dynamically tracks any stochastic signal drift or deviation, leading to unbiased random bit stream generation. The generated bit streams, due to their higher entropy, then only need to undergo simplified postprocessing. A prototype of the adaptive RNG system was experimentally implemented using discrete electronic components and a field programmable gate array for entropy source emulation. Statistical randomness tests based on the National Institute of Standards and Technology (NIST) test suite are conducted on bit streams obtained using the simulations as well as the discrete electronic component implementation, demonstrating that the bit streams consistently pass all 16 tests of the NIST SP 800-22 test suite with a 100% pass rate. Leveraging its simplified postprocessing, the adaptive RNG shows consistent operation across a wide range of throughputs from 5 to 182 Mbps. Our results validate the system’s ability to generate encryption-grade random bit streams at reduced hardware cost for IoT devices.

Since the first proofs of concept in electromagnetics concerning the possibility of invisibilizing the presence of an inclusion in a field, a considerable amount of research has been carried out with the objective of generalizing these properties to other areas of physics. The case of waves in elastic solids is still an open problem, since it has been shown that traditional theory cannot be applied to this more complex type of wave propagation. We propose a design methodology still based on the geometrical transformation initially used, no longer with the aim of transforming the governing equation of Kirchhoff–Love plates, but with the aim of generating curved waveguides that force bending waves to propagate in the direction advocated by the preliminary idea of cloaking. Numerical results show that the resulting metamaterial is capable of making an inclusion invisible over a wide frequency band for a unidirectional incident wave. In addition to the numerical results, we provide results from experiments conducted on the manufactured cloak, confirming the relevance of the proposed design.

Interfacial engineering provides an effective route to tailor chiral magnetic interactions in thin-film heterostructures relevant for spintronic applications. In this work, we investigate the influence of top capping layers on perpendicular magnetic anisotropy (PMA) and interfacial Dzyaloshinskii-Moriya interaction (iDMI) in ultrathin Co films. By depositing Ru, Ta, W, and Pt on a 1.7 nm Co layer, we selectively modify the top interface while preserving the intrinsic growth of the ferromagnetic layer. Ferromagnetic resonance, Brillouin light scattering, vibrating sample magnetometry, and magneto-optical Kerr effect measurements are used to quantify the magnetic anisotropy and chiral exchange. We find that Ta capping yields a strong PMA, leading to perpendicular, spontaneously oriented magnetization and an iDMI of $-1.23\mathrm{pJ}/\mathrm{m}$, exceeding that obtained with W. In contrast, Ru and Pt capping layers lead to in-plane and canted magnetization spontaneously, respectively. The large PMA observed in Ta-capped films allows increased Co thickness while maintaining perpendicular anisotropy, which is expected to enhance spin polarization. These results demonstrate that top-interface engineering enables simultaneous tuning of magnetic anisotropy and iDMI, providing a practical pathway toward the design of magnetic tunnel junctions incorporating stabilized skyrmions.

Faster random telegraph noise (RTN) in magnetic tunnel junctions (MTJs) would be beneficial for probabilistic computing applications. However, the interactions between the macrospin and spin waves with finite wave numbers reduce the RTN attempt frequency. We theoretically show that mode-selective heating and cooling by parametric excitation of Kittel mode or propagating spin waves can substantially increase or decrease the RTN frequency, respectively, and propose a nonlinear cooling mechanism that accelerates the switching dynamics. We outline experimental pathways to characterize the nonlinear processes that maximize the operation speed of MTJ-based probabilistic (p-) bits.

The quantum sensing landscape has been revolutionized by advanced technologies like superconducting circuits and qubit-based systems, which have furthered the ability to probe and understand fundamental properties of quantum matter. Here, we propose an integrated photonic device where a transmon qubit capacitively couples to a microwave cross-resonator, and the setup is employed for sensing of time-reversal-broken order in materials. In this sensing scheme, the transmon qubit plays a dual role as both a control element and a passive detector, while the photonic cross-resonator serves as the host for the sample, enabling a contact-free spectroscopic method suitable for studying materials where reliable electrical contacts are challenging to obtain, e.g., in van der Waal 2D heterostructures. We show that by tuning the coupling strength and phase between the transmon and the cross-resonator, the system allows selective control over the interaction dynamics and leads to a highly sensitive detection method that can be compactly understood in terms of the evolution of excited state population and quantum metric of the resonator-transmon hybrid state. This architecture has the potential to host a wide range of quantum phenomena that can be precisely encoded in the dynamics of the transmon qubit and, in this way, potentially allows access to elusive aspects of correlated materials.

Attosecond and sub-attosecond pulses in the deep-ultraviolet (DUV), vacuum-ultraviolet (VUV), and soft-x-ray regimes provide direct access to electron dynamics in different electronic shells on their natural timescales. Despite rapid experimental progress, the temporal characterization of broadband VUV pulses and ultrabroadband soft-x-ray attosecond pulses remains a central and largely unresolved challenge. Here, we introduce a single-shot pulse-reconstruction framework that, for the first time, combines direct numerical solutions of the three-dimensional time-dependent Schrödinger equation (3D-TDSE) with data-driven optimization. By abandoning semi-analytical response models and instead employing full electron dynamics as the forward mapping, the reconstruction signal acquires substantially enhanced sensitivity to ultrabroadband waveforms, even in the presence of strong Coulomb and strong-field effects. We demonstrate accurate and noise-robust reconstructions of isolated attosecond pulses, attosecond pulse trains, and femtosecond-to-attosecond VUV pulses in regimes where conventional strong-field-approximation (SFA) or perturbative model-based approaches fail. Our work establishes a fundamentally different paradigm for attosecond pulse metrology, enabling reliable single-shot characterization across the VUV and soft-x-ray spectral regions.

Hydrodynamic cloak design aiming to suppress water flow disturbance by objects has become a popular research topic, with promising applications in drag reduction and stealth technology for marine engineering, bioengineering, and chemical engineering. Existing methods primarily utilize transformation optics theory (TOT) to derive analytical solutions for anisotropic viscosity tensors, which then inform the design process. However, they are limited to the Stokes equations, i.e., a simplified form derived from the full Navier-Stokes (NS) equations at Reynolds number (i.e., $\mathrm{Re}$) $\ll 1$, which neglects the important nonlinear flow convection term. In this study, we propose a framework based on the physics-informed neural network (PINN) to guide the design of hydrodynamic cloaks under the full NS equations, thereby enabling the characterization of effects across a wide range of Reynolds numbers. Within this framework, the PINN is employed to learn the anisotropic viscosity tensor necessary to achieve the design objective of enhancing upstream and downstream velocity field similarity, effectively weakening wake disturbance. Based on the learned anisotropic viscosity tensor, multiple candidate cloaks can be designed and evaluated. The optimal cloaks are then determined by implementing computational fluid dynamics (CFD) validation. Additionally, CFD results for the optimal cloaks demonstrate that the proposed method is effective for both two-dimensional (2D) and three-dimensional (3D) flows at $\mathrm{Re}=1$, 100, and 400, achieving up to a 64.46% reduction in the relative root mean square error of the downstream velocity profile compared to the upstream one. Furthermore, the analysis of the cloak mechanism using the $Q$-criterion reveals that the cloaked object generates an expanded zero-$Q$-criterion region, where the deformation of the fluid parcel compensates for its rigid-body rotation. As a result, flow disturbances around the object are effectively minimized.

Multivalued quantum encoding maps a classical alphabet of $M>2$ symbols onto multiple prescribed states. Here, we experimentally demonstrate multivalued quantum encoding in an effective two-level subspace of the electron spin of a nitrogen-vacancy center in diamond at room temperature. Classical symbols are mapped onto either the qubit population (polar angle $\theta$) or the coherence (azimuthal angle $\varphi$) via microwave pulses with controlled durations or phases. By coherently preparing four distinct states within the electron-spin qubit, we demonstrate image reconstruction symbol by symbol. No decoding errors are observed for the tested finite datasets under the reported repetition settings. To enhance robustness to channel noise, we further integrate an error-adaptive joint source-channel coding (EAJSCC) neural codec, which achieves a 2% compression ratio with a structural similarity index (SSIM) of 0.78, compared with SSIM approximately equal to $0.24$ for a conventional baseline. These results establish a viable route toward higher information density in room-temperature solid-state spin platforms.

Phase boundary, the interface between neighboring physical phases in matter, hosts various emergent phenomena and has been a pivotal subject of research interest for decades. Conventional techniques for the spatial resolution of phase boundaries rely on the interaction between the sample and certain probing particles, in which a pristine surface after stringent sample preparation and high vacuum are usually mandatory. Here we show that phase boundaries in metallic alloys can be resolved by lock-in thermography (LIT) in an ambient environment, even in the presence of a coating layer. An alternating charge current is applied through the sample, and the phase boundaries are revealed by the Peltier effect therein. We employ the LIT to visualize the propagation of phase boundaries in superelastic NiTi wires during the martensitic phase transition and demonstrate its capability to detect the martensite phase in a dental rotary file during mechanical bending. Furthermore, imaging of the phase boundaries in FeRh is successfully achieved using the same method, thereby demonstrating its broad applicability. This work offers a general technique for phase-boundary visualization in metallic materials, enabling versatile in situ nondestructive defectoscopy of phase-transition alloys in service.