In non-Hermitian physics, exceptional points (EPs) hold great potential for quantum technologies, while optomagnomechanical (OMM) systems offer a versatile platform for exploring such effects. Here, we propose a third-order EP-enhanced OMM mass sensor, where the eigenfrequency evolution of the system is directly mapped to the optical cavity output spectrum. We demonstrate that the third-order EP delivers a strongly enhanced eigenfrequency response to tiny mass perturbations, achieving over two orders of magnitude higher frequency sensitivity than conventional EP-free OMM systems, without requiring strong optomagnomechanical coupling or high-intensity driving. The sensing mechanism relies on mass-induced mechanical frequency shifts that lift the EP degeneracy and split eigenfrequencies, enabling high-sensitivity detection via the linear scaling between the cube of the eigenfrequency shift and target adsorbed mass. Spectral analysis confirms optimal measured spectral resolution (MSR) at the EP under gain-dissipation balance, with the performance enhancement originating from the intrinsic properties of the third-order EP rather than cavity gain. This scheme breaks the sensitivity bottleneck of traditional OMM sensors, paving the way for ultrasensitive nanoparticle detection and quantum metrology.
The bulk photovoltaic effect (BPVE) is mostly studied in ferroelectric and piezoelectric systems with a sizable intrinsic and induced electric dipole moment. While most studies of BPVE are based on the conventional positive piezoelectric materials, their responses in negative piezoelectric systems remain rare. In this work, based on a minimum tight-binding model simulation, we adopt a chain model to illustrate how the BPVE evolves under mechanical deformation in negative piezoelectrics. We find that the BPVE responses are mainly governed by strain-induced shift vector variations. This is in contrast to the conventional positive piezoelectrics. Moreover, such a mechanism is further illustrated in realistic Te), via density functional theory calculations. Our work provides in-depth insights into BPVE engineering in unconventional negative piezoelectrics.
Machine-learning-driven molecular dynamics, powered by machine learning potentials (MLPs), is transforming the simulation of aqueous systems. By overcoming the long-standing trade-off between accuracy and efficiency inherent to traditional approaches, MLPs enable molecular simulations that achieve near-ab initio accuracy while reaching spatial and temporal scales relevant to complex water phenomena, such as hydrogen-bond dynamics, ion solvation, and chemical reactivity. This review synthesizes recent methodological and conceptual advances in MLP-based simulations of bulk water, aqueous solutions, and confined or interfacial environments, as well as reactive processes such as proton transfer and acid-base chemistry. Together, these developments establish MLPs as a unifying framework for elucidating the physics and chemistry of aqueous systems.
With the rapid development of sixth-generation (6G) intelligent wireless networks, environmental sensing has become a core requirement for many applications such as autonomous driving, drones, and intelligent robotics. Here, we propose a passive sensing method based on beam-focusing algorithms and a large-scale programmable metasurface composed of 64 & times; 96 effective elements. The coding patterns on the 1-bit programmable metasurface are dynamically switched via a field-programmable gate array (FPGA) to achieve real-time beam focusing and scanning at specific spatial locations. The reflected signal strength is then used to determine the target angle and distance. Requiring only a single RF channel and signal strength information, the system features a simple hardware architecture and low computational complexity. To verify the effectiveness and robustness of the proposed method, experiments are conducted across 74 positions within an azimuth-angle range from-70 degrees to 70 degrees and a distance range from 1 m to 3 m. The experimental results demonstrate that the proposed sensing method achieves high precision in both angle and distance for passive targets, with an average absolute angle error of 0.904 degrees and an average absolute distance error of 0.101 m. The proposed system provides a promising solution for applications in the Internet of Things, directional communication, and biomedical fields.
Conventional differential interference contrast (DIC) microscopy is inherently qualitative and lacks metrological capability, whereas high-precision techniques such as weak value amplification impose stringent experimental requirements. Here, we present a compact transmissive differential interferometric measurement system based on a birefringent crystal. By functioning as an interference element, the crystal enables quantitative differential interference measurements in both real space and momentum space. This approach avoids the dependence of weak value amplification on weak coupling and non-orthogonal state selection, while retaining and utilizing the inherent birefringent phase information of the crystal. We propose two modulation strategies and establish a unified theoretical model linking microscopic crystal parameters to macroscopic interferometric observations. Based on this model, the system can achieve an angular resolution on the order of 10-9 rad, which exceeds that of typical commercial polarimeters, and detects displacements as small as 0.35 nm, demonstrating nanometer-scale sensing capability. Owing to its compact design and tunable parameters, this system offers a compact quantitative approach for high-precision applications, including chiral sensing, nanometrology, and quantum material analysis.
The KV2Se2O Rb1-delta V2Te2O , and Cs1-delta V2Te2O are experimentally confirmed to adopt either C-type or G-type antiferromagnetic configuration, corresponding to apparent or hidden altermagnetism. However, their nearly degenerate energies lead to inconsistent experimental assignments between the two antiferromagnetic configurations. Here, we predict that the experimentally synthesized is a robust d-wave altermagnetic RbCr2Se2O metal, since the energy difference between C-type and G-type configurations is large, which is independent of electron correlation strength and van der Waals interaction. Upon applying in-plane uniaxial strain, RbCr2Se2O magnetic effect, which is distinct from semiconductor that typically requires carrier doping in addition to strain. This provides an experimental strategy for distinguishing the G-type antiferromagnetic configuration, in which the total magnetic moment remains zero under uniaxial strain. Our work presents an isostructural d-wave altermagnetic analogous RbCr2Se2O to KV2Se2O Rb1-delta V2Te2O , and Cs1-delta V2Te2O, which can facilitate further experimental verification. Furthermore, these results are universal across materials of this family (X = K, Rb, Cs; Y = S, Se, Te), thus expand-XCr2Y2O ing the family of altermagnets.
Vortex beams carrying orbital angular momentum (OAM) possess infinite-dimensional orthogonal eigenstates, rendering them exceptionally valuable for optical communication and information transmission applications. However, the sorting and recognition of OAM encounter formidable challenges in practical scenarios, especially when propagating through dynamic scattering media. Mode mixing and decoherence induced by time-varying perturbations severely restrict the effective exploitation of OAM. Traditional studies have predominantly focused on the interaction between vortex beams and static scattering media. Even for dynamic scattering media, existing investigations generally rely on synchronous speckle acquisition or deep learning for information retrieval, which inevitably results in complex system configurations or prohibitive computational overheads. To address these issues, this paper proposes an OAM sorting and recognition method for randomly rotating scattering media. By integrating the angularly averaged intensity cross-correlation function with a normalized cross-correlation screening (NCCS) algorithm, we establish a mapping relationship between the topological charge difference and the characteristic features of the cross-correlation ring (CCR). Furthermore, complete sorting and recognition of OAM modes are realized through the dual-reference perfect vortex beam (DRPVB) approach. Experimental results demonstrate that our method successfully overcomes the technical limitations of conventional synchronous speckle acquisition, enabling OAM sorting and recognition under randomly rotating media conditions and thus facilitating the practical application of vortex beams in optical communication and information processing applications.
Valley degree of freedom, an intrinsic property of electrons, provides a novel dimension for information storage and processing. For most conventional valleytronic materials, however, stable and tunable valley polarization (VP) is usually realized based on spin-orbit coupling (SOC), which significantly limits material choices and operational flexibility. Altermagnetism - a novel magnetic order characterized by compensated magnetic order with vanishing net magnetization, broken inversion symmetry, and momentum-dependent spin splitting - offers a revolutionary solution to overcome this bottleneck. Originating from the coupling of altermagnetism and ferrovalley (FV) physics, the altermagnetic ferrovalley (AMFV) materials enable robust, tunable, and spontaneous spin-valley locking independently of strong SOC. This review systematically outlines the advances in AMFV materials. It begins by revisiting the types and limitations of traditional FV systems, then delves into the physical nature of altermagnetism and the symmetry principles underlying its integration with valley physics. Subsequently, it categorizes and reviews the latest theoretical and experimental progress on representative AMFV materials (e.g., V2Se2O, Fe2MX4), focusing on elucidating their multi-degree-of-freedom coupling characteristics (such as spin-valley-optical coupling) and their modulation mechanisms under external stimuli, including strain, electric field, sliding, twisting, and proximity effects. These AMFV systems hold enormous application potential in valley tunnel junctions and non-volatile memory, yet they still face challenges such as material scarcity, unclear mechanisms, and a lack of device-level exploration. Future efforts should leverage the synergy of high-throughput computation, advanced characterization techniques, and device development to drive breakthroughs and accelerate the development of next-generation information technologies.
Non-Hermitian quantum systems - characterized by parity-time symmetry and the emergence of exceptional points - have attracted increasing interest, particularly in light-matter interaction platforms where dissipation and radiative losses play a fundamental role. In this work, we investigate the modulation of coupling states between atomic energy levels during the generation of backward W-state triphotons via a spontaneous six-wave mixing (SSWM) process. By employing tunable external control beams, we realize dynamic modulation from the weak to the strong coupling regime, accompanied by a qualitative transition in triphoton coincidence statistics from anti-bunching to damped Rabi oscillations. Remarkably, the appearance of single exponential decays in the triphoton coincidence count traces marks the onset of an exceptional point in the non-Hermitian system. Furthermore, triphoton correlations in the tau 21 and tau 31 directions can be independently modulated by selectively tuning of the coupling state via and , respectively. These results provide a versa-ED1 ED2 tile and coherent platform for the one-step generation of backward entangled triphoton states and offer a promising approach to engineering high-dimensional entanglement, with potential applications in quantum communication and quantum information processing.
Two-dimensional (2D) photoinduced lattices in atomic ensembles constitute an ideal platform for the systematic investigation of light-matter interactions and controllable diffraction phenomena. Nevertheless, existing research efforts have primarily concentrated on fixed or symmetric lattice configurations, resulting in insufficient exploration of asymmetric diffraction behaviors. Herein, we theoretically propose a 2D phase-controllable photoinduced lattice, which is constructed by overlapping two identical sublattices with independently tunable spatial phases within an atomic ensemble. Spatial phase difference between the two sublattices can be controlled directly by tuning the initial phase of the lattice-forming beams, eliminating the need for complex optical path designs and tedious system optimization. We demonstrate that the absorption, dispersion, and transmission properties of the proposed lattice can be dynamically tuned via photon detuning, leading to the generation of both amplitude-and phase-type lattices. Notably, the amplitude-type lattices exhibit insensitivity to phase variations, whereas the phase-type lattices demonstrate remarkable phase-dependent energy transfer effects and pronounced directional asymmetry. Specifically, a one-dimensional (1D) spatial phase difference between the two identical sublattices induces stripe-like modulation, whereas a 2D spatial phase difference yields reconfigurable anisotropic 2D modulation patterns. Furthermore, we demonstrate that the combined modulation of detuning and spatial phase difference induces periodic asymmetric oscillations in diffraction energy, enabling precisely controllable asymmetric distribution of diffraction. Our work establishes a comprehensive theoretical framework for phase-driven asymmetric diffraction in photoinduced lattices and provides an effective strategy for the development of dynamically reconfigurable all-optical nonreciprocal photonic devices.
