Quantum anomalous Hall insulators (QAHIs) are an ideal platform for exploring exotic quantum phenomena, yet typically depend on strong relativistic effects to achieve a substantial bandgap. Here, we propose a symmetry-lowering strategy for designing robust QAHIs without introducing heavy elements. Using the tetragonal space group as a prototypical system, we find that reducing symmetry from P4/nmm to Pmmn activates hybridization of distinct orbital sets near the Dirac cone, producing a large topological bandgap in correlated systems. First-principles calculations identify the Pmmn VAs monolayer as a high-temperature QAHI with a bandgap of 1018 meV, much larger than 857 meV of its P4/nmm counterpart. This strategy also facilitates bandgap engineering in QAHIs via symmetry manipulation, such as strain and substrate applications.

Optically levitated nanoparticles in vacuum experience both electrostatic and light-induced dipole-dipole interactions, offering a versatile platform to explore mesoscopic entanglement and many-body dynamics. A significant challenge in optical trap arrays is to achieve site-resolved, point-to-point tunability: adjusting the laser parameters of a single trap typically induces global cross-talk to neighboring sites, hindering independent control. Inspired by tunable couplers in superconducting circuits, we implement an ancillary nanoparticle that functions as a coupler between two target nanoparticles. Within a reconfigurable three-particle array, we demonstrate broad tunability of the direct dipole-dipole interaction by controlling the phase and position of the traps. In addition, we observe spectral signatures consistent with mediated interactions between the target particles via the ancillary one, manifested as mode participation beyond the uncoupled response. Our results establish a practical route to tailored, site-resolved control in multi-particle optical trap arrays, expanding the optical-binding toolbox and opening opportunities for programmable oscillator networks relevant to macroscopic quantum mechanics and precision sensing.

Label-free optical microscopy through absorption or scattering spectroscopy provides fundamental insights across biology and materials science, yet its sensitivity remains fundamentally limited by photon shot noise. While recent demonstrations of quantum nonlinear microscopy show sub-shot-limited sensitivity, they are intrinsically limited by availability of high peak-power squeezed light sources. Here, we introduce squeezing-enhanced photothermal (SEPT) microscopy, a quantum imaging technique that leverages twin-beam quantum correlations to detect absorption induced signals with unprecedented sensitivity. SEPT achieves 3.5 dB noise suppression beyond the standard quantum limit, enabling a 2.5-fold increase in imaging throughput or 31

The quantized Hall response of Landau levels (LLs) provides a paradigmatic mechanism for the quantum Hall effect, where successive LLs contribute chiral edge channels. Pseudo Landau levels (pLLs), generated by strain in Dirac materials, faithfully mimic the LL spectrum but are widely believed to be incapable of supporting a quantized Hall conductivity because the associated pseudomagnetic field preserves time-reversal symmetry and the Hall response at the two valleys cancel. A natural question is whether pLLs can induce a quantum Hall effect without requiring a real magnetic field. By introducing a modified Haldane term, we lift the valley degeneracy of the pLL ladders without distorting the pLL quantization. As a result, multiple pLL branches with the same chirality induce a quantized Hall effect with high plateaus at zero magnetic flux. We establish this mechanism using an analytically solvable Fock-state lattice model and demonstrate its robustness in a strained honeycomb tight-binding lattice. Furthermore, we propose a feasible implementation in a cavity quantum electrodynamics platform, where strain and synthetic gauge fields can be programmably engineered.

Advances in spectroscopic measurement and imaging technologies have become key tools in life sciences and materials science.However,for samples with weak optical responses,such as low-dimensional materials and living cells,high-power excitation light often introduces significant classical noise and causes non-negligible photodamage,thereby limiting the achievable signal-to-noise ratio(SNR)and the application scope.In this context,nonclassical light sources with unique quantum properties,such as entangled light and squeezed light,provide a promising route to surpass classical limits in SNR.This review focuses on the field of quantum-enhanced spectroscopy and imaging,and systematically reviews recent progress based on two important types of quantum light sources:entangled light and squeezed light.Owing to quantum correlations between photons,entangled light exhibits remarkable robustness against noise in applications such as correlation imaging,undetected-photon imaging,and ultrafast interferometric measurements.In contrast,squeezed light improves detection sensitivity and SNR by reducing quantum noise in the optical field,enabling enhanced performance in displacement sensing,plasmonic detection,and nonlinear microscopic imaging.Furthermore,this article systematically discusses the unique advantages of quantum light sources in improving SNR,reducing photodamage,enhancing temporal resolution,and increasing nonlinear conversion efficiency.It also analyzes key challenges that currently limit the practical implementation of quantum imaging technologies,including the low brightness of quantum light sources and large system losses.Finally,we discuss the future directions in this field.

We theoretically study the impact of magnetic sublevels on superradiance lattices (SLs) in room temperature 87Rb vapor. By incorporating the full Zeeman manifold into the master-equation framework, we demonstrate that the presence of magnetic sublevels significantly modifies the velocity-scanning tomography spectra of SLs. Our simulations reveal that two specific optical configurations exhibit clear lattice features while being robust against collision effects, making them favorable for experimental realization. Furthermore, we explore the influence of an external magnetic field, which lifts the degeneracy of Zeeman sublevels and enables multiple distinguishable SLs. These findings not only clarify the discrepancies between simplified SL models and experimental observations, but also pave the way for constructing spin-dependent SLs.

Floquet modulation plays a crucial role in manipulating the phases of quantum matter. However, experimentally characterizing the Floquet topological phase transition, particularly in one-dimensional systems, remains challenging. In this study, we investigate the Floquet topological phase transition within the Su-Schrieffer-Heeger model in room-temperature superradiance lattices. Due to their resilience to thermal noise, superradiance lattices can undergo strong phase modulation to synthesize an effective AC electric field via Peierls substitution. Since the one-dimensional momentum-space Su-Schrieffer-Heeger model breaks time-reversal symmetry, we can classify the topologically distinct phases through optical nonreciprocity. We observe the topological phase transition induced by effective AC and DC electric fields, successfully mapping the complete phase diagram. Our results provide a novel spectroscopic approach to characterizing the topological phase transitions of Zak phases, which can contribute to the exploration of other non-equilibrium topological phases under strong modulation.

Topological physics provides novel insights for designing functional photonic devices, such as magnetic-free optical diodes, which are important in optical engineering and quantum information processing. Past efforts mostly focus on the topological edge modes in two-dimensional (2D) photonic Chern lattices, which, however, require delicate fabrication and temporal modulation. In particular, the 1D nonreciprocal edge mode needs to be embedded in a 2D lattice, contradicting with the compactness of integrated photonics. To address these challenges, we investigate the optical nonreciprocity of the 1D Su-Schrieffer-Heeger (SSH) superradiance lattices in room-temperature atoms. The probe fields propagating in two opposite directions perceive two different SSH topological phases, which have different absorption spectra due to the interplay between the Zak phase and the thermal motion of atoms, resulting in optical nonreciprocity. Our findings reveal the relationship between 1D topological matter and optical nonreciprocity, simplifying the design of topologically resilient nonreciprocal devices.

An optical levitation system in a vacuum is an efficient system to investigate the dynamics of isolated micro- and nanoparticles. However, the motion and stability of the trapped particles in this system can be affected by the internal temperature, which remains a challenge to measure. Conventional methods are constrained by material specificity or lack the capability for direct temperature measurement. Here, we demonstrate the application of Raman thermometry for non-contact temperature detection of an optically levitated fused silica sphere in vacuum. In addition, the experimental results reveal a linear increase in particle temperature with laser power, consistent with photothermal theory. The integration of Raman thermometry with the optical levitation system enables high-precision thermal sensing at the microscale, offering significant potential for applications in precision metrology and fundamental physics.

Topological materials hold great promise for developing next-generation devices with transport properties that remain resilient in the presence of local imperfections. However, their susceptibility to thermal noise has posed a major challenge. In particular, the Haldane model, a cornerstone in topological physics, generally requires cryogenic temperatures for experimental realization, limiting both the investigation of topologically robust quantum phenomena and their practical applications. In this work, we demonstrate a room-temperature realization of the Haldane model using atomic ensembles in momentum-space superradiance lattices, a platform intrinsically resistant to thermal noise. The topological phase transition is revealed through the superradiant emission contrast between two timed Dicke states in the lattice. Crucially, the thermal resilience of this platform allows us to access a deep modulation regime, where topological transitions to high Chern number phases emerge – going beyond the traditional Haldane model. Our results not only deepen the understanding of exotic topological phases, but also offer a robust, reconfigurable, and room-temperature-compatible platform that connects quantum simulation to real-world quantum technologies.

Optically levitated particles in high vacuum offer an exceptionally isolated mechanical platform for photonic control. Effective cooling of their center-of-mass motion is essential not only for enabling ultrasensitive precision sensing but also for opening access to the quantum regime where macroscopic superposition and nonclassical states can be realized. In this review, we present a comprehensive overview of recent advances in active feedback cooling, based on real-time photonic modulation, and passive feedback cooling, driven by optomechanical interactions within optical resonators. We highlight key experimental milestones, including ground state cooling in one and two dimensions, and discuss the emerging applications of these systems in force sensing, inertial metrology, and macroscopic quantum state preparation. Particular attention is given to novel proposals for probing quantum gravity, detecting dark matter and dark energy candidates, and exploring high-frequency gravitational waves. These advancements establish levitated optomechanical systems as a powerful platform for both high-precision metrology and the investigation of fundamental quantum phenomena. Finally, we discuss the current challenges and future prospects in cooling multiple degrees of freedom, device integration, and scalability toward future quantum technologies.

Low-frequency (LF) wireless communications play a crucial role in ensuring anti-interference, long-range, and efficient communication across various environments. However, in conventional LF communication systems, their antenna size is required to be inversely proportional to the frequency, so that their mobility and flexibility are greatly limited. Here we introduce a novel prototype of LF receiving antennas based on optically levitated nanoparticles, which overcomes the size-frequency limitation to reduce the antenna size to the hundred-nanometer scale. These charged particles are extremely sensitive to external electric field as mechanical resonators, and their resonant frequencies are adjustable. The effectiveness of these antennas was experimentally demonstrated by using the frequency shift keying (2FSK) modulation scheme. The experimental results indicate a correlation between error rate and factors such as transmission rate, signal strength, and vacuum degree with a signal strength of approximately 0.1V/m and a bit error rate below 0.1%. We extend the application of levitated particle mechanical resonators as an entirely new type of compact LF antennas, which may be utilized in long-distance communications in extreme environments.

For three-dimensional systems, discussing the possibility of implementing quantum Hall physics has been an enduring topic. Based on Weyl semimetals, pioneering works have proposed chiral Landau levels and three-dimensional quantum Hall effect. When the degenerate band extends from nodal points to nodal lines, the magnetic field can lead to various quantum Hall phenomena, such as the three-dimensional flat Landau levels. Usually, the above exotic phenomena are explored under a uniform magnetic field with a fixed direction and magnitude. Here, we obtain a momentum-dependent pseudomagnetic field in a nodal line semimetal by designing a gradient coupling. The resulting quantum Hall surface states exhibit momentum-dependent chiral and helical transport features. These findings are experimentally confirmed in the phononic crystal platform. The novel sound transport may pave the way for acoustic devices with unconventional functions.

Landau levels (LLs) are of great importance for understanding the quantum Hall effect and associated many-body physics. Recently, their three-dimensional (3D) counterparts, i.e., dispersionless 3D LLs with well-defined quantum numbers, have attracted significant attention but have not yet been reported. Here we theoretically propose and experimentally observe 3D LLs with a sharply quantized spectrum in a diamond acoustic lattice, where the eigenstates are characterized by SU(3) quantum numbers. The engineered inhomogeneous hopping strengths not only introduce pseudomagnetic fields that quantize the nodal lines into LLs but also provide three bosonic degrees of freedom, embedding a generic SU(3) symmetry into the LLs. Using a phased array of acoustic sources, we selectively excite distinct eigenstates within the degenerate LL multiplets and visualize their 3D eigenmodes. Importantly, our approach enables the precise reconstruction of SU(3) quantum numbers directly from eigenmode correlations. Our results establish SU(3) LLs as a tractable model in artificial platforms, and pave the way for synthesizing LLs with zero dispersion and countable quantum numbers in arbitrary dimensions.

Topologically protected boundary transport is a promising route to realize robust quantum manipulation between distant nodes. Conventional topological transports require a long transmission time to meet adiabatic evolution, which unfortunately becomes a significant obstacle for practical quantum systems with decoherence. Here, we report a fast and robust phonon transfer by breaking this adiabatic limitation in a one-dimensional nanomechanical topological interface lattice. The high-fidelity nonadiabatic topological transfer (NTT) can be predicted accurately via the localized mode and bulk levels. A dynamical method is then put forward to characterize the nonadiabatic oscillation of the NTT according to the chiral symmetry, and the oscillation of the instantaneous adiabaticity is measured by the phonon population on the even nanomechanical resonators. Furthermore, we confirm the robustness under various noises and the scalability of the NTT. Our results open the door to accelerating topological transport, which is valuable for developing fast and robust quantum information transfer protocols.

Topology has become important in understanding condensed matter physics and photonics, such as the quantum Hall effect. Recently, interest has grown in applying topology to stochastic systems, including biological active matter. In this study, we explore stochastic topological physics using optically levitated particles in arrays of optical tweezers. We describe the particle dynamics with the Langevin and master equations, mapping the latter to a tight-binding model called the Markov network. By changing the escape rates between traps, we create the Su-Schrieffer-Heeger (SSH) model and show the existence of topologically protected edge states. Our theoretical and simulation results connect the decay rates of particles at certain sites to these topological states. This research provides, to our knowledge, a new way to study topological physics in stochastic systems with the precise control and measurement capabilities of optical tweezers. (c) 2024 Optica Publishing Group. All rights, including for text and data mining (TDM), Artificial Intelligence (AI) training, and similar technologies, are reserved.

Fock-state lattices (FSLs) consist of the Fock states of photons and atoms, establishing a quantum photonic platform for simulating condensed matter physics. Remarkably, various topological phenomena, such as topological edge states, strain-induced Landau levels, the valley Hall effect, and the quantum anomalous Hall effect, are intricately linked to the quantum properties of light. Recent advancements in state-of-the-art superconducting circuits have enabled the observation of these topological quantum photonic phenomena. With scalable dimensions and flexible structure engineering, FSLs offer a novel tool for investigating high-dimensional topological physics and devising innovative devices for quantum information processing. This review delves into the latest theoretical and experimental developments in this emerging field, situated at the intersection of quantum optics, topological physics, and quantum information. {GRAPHIACAL ABSTRACT}

Quantum simulation offers an analog approach for exploring exotic quantum phenomena using controllable platforms, typically necessitating ultracold temperatures to maintain the quantum coherence. Superradiance lattices (SLs) have been harnessed to simulate coherent topological physics at room temperature, but the thermal motion of atoms remains a notable challenge in accurately measuring the physical quantities. To overcome this obstacle, we implement a velocity scanning tomography technique to discern the responses of atoms with different velocities, allowing cold-atom spectroscopic resolution within room-temperature SLs. By comparing absorption spectra with and without atoms moving at specific velocities, we can derive the Wannier-Stark ladders of the SL across various effective static electric fields, their strengths being proportional to the atomic velocities. We extract the Zak phase of the SL by monitoring the ladder frequency shift as a function of the atomic velocity, effectively demonstrating the topological winding of the energy bands. Our research signifies the feasibility of room-temperature quantum simulation and facilitates their applications in quantum information processing.

As a typical application of photon momentum transfer, optically levitated systems are known for their ideal isolation from mechanical dissipation and thermal noise. These characteristics offer extraordinary potential for acceleration precision sensing and have attracted extensive attention in both fundamental and applied physics. Although considerable improvements of optically levitated accelerometers have been reported, the dynamic testing of the sensing performance remains a crucial challenge before utilization in practical application scenarios. In this work, we present a dual-beam optically levitated accelerometer and demonstrate a test with dynamic inputs for the first time. An acceleration sensing sensitivity of 0.1 mu g (g = 9.8 m/s2) and a measurement range of 1 g are achieved. These advancements solidify the potential of optically levitated accelerometers for deployment in practical domains, including navigation, intelligent driving, and industrial automation, building a bridge between laboratory systems and real-world applications.

As a typical application of photon momentum transfer, optical levitation systems are known for their ideal isolation from mechanical dissipation and thermal noise. These characters offer extraordinary potential for acceleration precision sensing and have attracted extensive attention in both fundamental and applied physics. Although considerable improvements of optical levitation accelerometers has been reported, the dynamic testing of the sensing performance remains a crucial challenge before the utilization in practical application scenarios. In this work, we present a dual-beam optical levitation accelerometer and demonstrate the test with dynamic inputs for the first time. An acceleration sensing sensitivity of $0.1\mu g$ and a measurement range of $ 1g$ are achieved. These advancements solidify the potential of optical levitation accelerometer for deployment in practical domains, including navigation, intelligent driving, and industrial automation, building a bridge between the laboratory systems and real-world applications.