The ingenious scheme we propose for achieving unidirectional reflection lasing (URL) onset involves integrating a one-dimensional defective atomic lattice with a coherent-gain atomic system. Its physical essence lies in the fact that the right-side reflectivity is drastically reduced due to the destructive interference between direct and secondary reflections, whereas on the left-side direct reflection is effectively suppressed and the secondary reflection is efficiently enhanced, ultimately reaching the lasing threshold. Through numerical results and further analyses, we have elucidated how to precisely tailor the lattice parameters and coupling fields to control the destructive-interference point, thereby enabling the onset and active modulation of URL. Our scheme not only effectively circumvents the stringent structural-parameter tuning process required to directly reach the URL onset, but also benefits the integration of active photonic devices into compact quantum networks and may improve the efficiency of optical information transmission.

We propose an efficient scheme for achieving mode-tunable unidirectional reflection lasing (URL) by establishing a coherent gain atomic system to amplify the probe field and ingeniously designing a one-dimensional (1D) defective atomic lattice. This lattice not only replaces the resonant cavity to provide a distributed feedback mechanism but also breaks the spatial symmetry of the probe susceptibility. Correspondingly, the URL can be characterized by a non-Hermitian degenerate spectral singularity (NHDSS), where the two eigenvalues of the inverse scattering matrix are engineered to satisfy λS-1+≃λS-1-→0. This intriguing NHDSS depends on the probe susceptibility and the Bragg condition, both of which can be modulated by adjusting the external driving fields and lattice structure, rendering the scheme experimentally feasible. Our approach achieves both nonreciprocity and lasing oscillation in a single system, significantly enhancing the efficiency of optical information transmission and facilitating the integration of active photonic devices into compact quantum networks.

We investigate entanglement transfer in a multi-giant-atom waveguide system. By tailoring chiral spontaneous emission and exploiting dark-state dynamics, the setup enables perfect, unidirectional sequential or selective transfer of quantum states and their associated entanglement. The distance between two entangled atoms, i.e., the entanglement length, can be dynamically adjusted, allowing robust conversion between long-range and short-range entanglement during propagation. The system inherently converges to a dark state, guaranteeing high-fidelity directional transfer. When the additional phase is modulated as a periodic piecewise function, spatially separated giant atoms exhibit stable, nearly lossless state exchange and maintain steady entanglement even under non-Markovian conditions. This behavior mimics conventional braided architectures without suffering from propagation delays or spatial restrictions. Our proposal offers a scalable pathway for continuous long-distance entanglement transport and resilient state exchange in quantum networks.

Unidirectional reflection amplification is a desirable functionality for nonreciprocal photonic components. We propose an inversionless route to this effect in a homogeneous ensemble of a three-level A-type atomic system using a spatially graded coupling field. The linear position dependence of the coupling strength breaks the spatial symmetry of the optical susceptibility, enabling strong reflection from one side while suppressing the counterpropagating reflection channel. With the assistance of spontaneously generated coherence and a weak incoherent pumping field, the medium provides coherent gain without population inversion, resulting in essentially unidirectional reflection amplification, including the emergence of dual amplification bands. Moreover, both the magnitude and spectral location of the amplification can be reconfigured by tuning the relative phase, detuning, and intensity of the coupling field, offering flexible control over the nonreciprocal response. These results establish a simple, nonmagnetic, and highly tunable platform for realizing reflection-type nonreciprocal amplifiers and related functionalities, with potential applications in quantum optics and integrated photonic devices.

To emulate the human color vision system, developing artificial optoelectronic synapses with multiwavelength discrimination capability is highly desired. In this work, we propose a novel optoelectronic memristor based on a Gelatin-ZnO@Sodium copper chlorophyllin (SCC) nanocomposite film. The device exhibits distinguishable response behaviors under red (680 nm), green (540 nm), and blue (430 nm) light stimuli, which enables color image perception and memory functions. Furthermore, by integrating optical potentiation and electrical depression behaviors, we implement the functionality of color image recognition in artificial neural networks. The accuracy exceeds 97.7% after only 350 training epochs. The wavelength-dependent photoresponse can be attributed to the wide absorption range of SCC and efficient carrier separation at the ZnO/SCC interface. This work provides new insights for developing efficient, multiwavelength neuromorphic vision system.

Unidirectional lasing is highly desirable for practical high-performance quantum information processing platforms, while most existing schemes still rely on the combination of resonant cavities and nonreciprocal mechanisms. Here, we propose a cavity-free scheme for achieving the onset of narrowband unidirectional reflection lasing (URL) in a single physical system by introducing a coherent gain atomic medium into a one-dimensional defective atomic lattice, where the former amplifies the probe field and the latter provides spatial symmetry breaking and a distributed-feedback mechanism. We show that the threshold condition for URL, characterized by λ+-1≃λ--1→0, can be tuned from single-mode to dual-mode by varying the microwave field and the lattice structure. Its underlying mechanism lies in the constructive or destructive interference between the reflections from both sides under distinct Bragg conditions.

Electrochemical metallization (ECM) memristors, with their advantages of high ON/OFF ratio, fast switching speeds, and low power consumption, have shown broad prospects in emerging applications such as neuromorphic computing, low-power logic computing, and artificial intelligence hardware. To fully realize the potential of ECM memristors, it is necessary to gain a deep understanding of the complexity of ion migration and redox reactions associated with resistive switching at the nanoscale. This review first systematically elucidates the resistive switching mechanism of ECM memristors, then focuses on discussing various novel physical effects emerging at the nanoscale, including the nanobattery effect, quantized conductance effect, diffusion effect, photo-induced resistive switching effect, and bio-voltage effect. A further review of the latest application advancements of these effects in cutting-edge fields such as artificial synapses, bioelectronic interfaces, in-memory computing, and neuromorphic perception. Finally, we explored the key challenges and potential opportunities facing ECM memristors in their future development, aiming to lay the groundwork for future neuromorphic computing research.

Simultaneously realizing nonreciprocity and signal amplification in the same physical system cannot only greatly enhance the efficiency of nonreciprocal photonic devices but also facilitate their integration. We propose a scheme to achieve gain-assisted nonreciprocal or even unidirectional reflection amplification by exploring spontaneously generated coherence (SGC) activated by a weak incoherent pump in a defective atomic lattice. The numerical results show that the monochromatic to two-color nonreciprocal reflection amplification (the maximum of reflectivities Rl similar or equal to 104 and Rr similar or equal to 102), and even unidirectional reflection amplification (Rl similar or equal to 102 and Rr similar or equal to 10-4) can be modulated freely by adjusting the relative phase phi, the dipole moment angle theta and the parameters of defective atomic lattice, e.g., the number and period of vacant lattice cells, the period of filled lattice cells, and so on. This indicates that nonreciprocal reflection amplification can be enhanced and modulated via the SGC effect and multiple reflections within the atomic lattice. Such efficient nonreciprocal amplification can be effectively applied to integrated chips, thereby advancing the development of quantum information technology. (c) 2026 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement

We skillfully utilized vacuum induced coherence to amplify the probe light, and then successfully achieved both nonreciprocal reflection and lasing oscillation in a single physical system by leveraging the distributed feedback and spatial symmetry breaking effect of the one-dimensional defective atomic lattice. This innovative scheme for realizing unidirectional reflection lasing (URL) is based on both non-Hermitian degeneracy and spectral singularity (NHDSS, means λ_+^-1_-^-1→0). Therefore, we analyze the modulation of parameters such as the lattice structure and external optical fields in this system to find NHDSS point, and further verified the conditions for its occurrence by solving the transcendental equation of susceptibility satisfying the NHDSS point, as well as analyzed its physical essence. Our mechanism is not only beneficial for the integration of photonic devices in quantum networks, but also greatly improves the efficiency of optical information transmission.

The novel and ingenious scheme we propose for achieving unidirectional reflection lasing (URL) involves integrating a one-dimensional (1D) defective atomic lattice with a coherent gain atomic system. Its physical essence lies in the fact that the right-side reflectivity is drastically reduced due to the destructive interference between primary and secondary reflections, whereas on the left-side primary reflection is effectively suppressed and the secondary reflection is efficiently enhanced, ultimately reaching the lasing threshold. Through numerical results and further analyses, we have elucidated how to precisely tailor the lattice parameters and coupling fields to control destructive interference point (DIP), thereby realizing URL and enabling its active modulation. Our scheme is experimentally feasible and not only effectively circumvents the stringent conditions faced in directly realizing URL, providing a new pathway, but also beneficial for integrating active photonic devices into compact quantum networks and may improve the efficiency of optical information transmission.

In order to further investigate the non-reciprocity of light propagation in the defective atomic lattices,and due to its effective application in designing novel photonic devices,such as all-optical diodes and isolators,which are powerful tools for information processing and quantum simulation,we innovatively propose to use the Fibonacci sequence to modulate the arrangement of empty lattice cells that form a quasi periodic defective atomic lattices.In the electromagnetically induced transparency window,the probe light is almost not absorbed under the control of a strong coupling field(see Fig.1).The numerical simulation indicates that a wide nonreciprocal reflection band can be achieved by modulating the number of filled lattice cells,Fibonacci sequence,the period number in a single quasi period(see Fig.2).These results provide more degrees of freedom for regulating nonreciprocal reflection with wide bandwidth and high contrast,and have potential applications in quantum computing and information processing.

In the regime of Rydberg electromagnetically induced transparency, we study the correlated behaviors between the transmission spectra of a pair of probe fields passing through respective parallel one-dimensional cold Rydberg ensembles. Due to the van der Waals (vdW) interactions between Rydberg atoms, each ensemble exhibits a local optical nonlinearity, where the output EIT spectra are sensitive to both the input probe intensity and the photonic statistics. More interestingly, a nonlocal optical nonlinearity emerges between two spatially separated ensembles, as the probe transmissivity and probe correlation at the exit of one Rydberg ensemble can be manipulated by the probe field at the input of the other Rydberg ensemble. Realizing correlated Rydberg EITs holds great potential for applications in quantum control, quantum network, quantum walk and so on.

We developed an effective theoretical method to examine the successive propagation dynamics of a gate field and a signal field in an EIT medium of Rydberg atoms exhibiting both self and cross van der Waals (vdW) interactions. It is found that the slow-light storage of this gate field can be achieved with an efficiency up to 73.5% and a negligible modification of photon statistics. More interestingly, even a single stored gate photon can effectively attenuate the otherwise low-loss signal field containing hundreds of photons during its slow-light transport by exploiting the cross vdW interaction. Therefore, benefiting from a direct insight into the simulated propagation dynamics, we have demonstrated that a high-performance all-optical transistor is feasible with its optical gain (22) and contrast (0.999), two important figures of merit, both better than those reported in relevant experiments. More importantly, through the transistor process, we can obtain single photons that exhibit low biphoton correlation and a uniform distribution, distinct from the previous storage process.

Improving the performance of non-reciprocal photonic devices is one of the key factors for promoting the development of quantum networks. To achieve this goal, we propose a scheme to realize multicolored unidirectional reflection amplification in the defective atomic lattice, with all atoms trapped in each filled lattice cell being driven into a four-level diamond-type coherent gain atomic system by two coupling fields and two probe fields. Therefore, this scheme simultaneously achieves light amplification (resulting from the joint effect of the coherent gain atomic system and the distributed feedback mechanism of the atomic lattice) and non-reciprocity (arising from the symmetry-breaking effect of the defective atomic lattice) in a single physical system. Furthermore, we propose a reasonable scheme for obtaining equivalent results by reducing the energy level structure, and through numerical simulations and calculations, it is concluded that perfect unidirectional reflection amplification requires that the two-photon resonance is not only located in the gain region, but also satisfies the Bragg condition. This scheme can be used to design non-reciprocal photonic devices that are easily integrable, high-efficiency, and capable of flexible multi-channel manipulation.

We investigate steady-state entanglement in a hybrid optomechanical cavity coupled to a Rydberg atomic ensemble confined within a single blockade region. The ensemble behaves as one superatom due to the rigid dipole blockade effect. Through optomechanical coupling, three types of bipartite entanglement emerge among the cavity, the Rydberg superatom, and the movable mirror. As the principal quantum number of the Rydberg atoms increases (leading to reduced atomic decay rates), the direct cavity–mirror coupling entanglement is redistributed into direct cavity–superatom coupling entanglement and indirect superatom–mirror coupling entanglement. Counterintuitively, this redistribution culminates in the complete suppression of two direct coupling entanglements, leaving only the indirect coupling entanglement persistent under resonant Stokes sideband conditions. Systematic parameter tuning reveals entanglement transfer pathways and establishes the preference of the superatom–mirror entanglement for specific principal quantum numbers. Furthermore, we demonstrate the thermal robustness of the surviving entanglement up to experimentally accessible temperatures. These findings advance the understanding of quantum entanglement in hybrid quantum systems and suggest applications in quantum information processing.

Nonreciprocal entanglement, characterized by inherently robust operation, is a cornerstone for quantum information processing and communications. However, it remains a great challenge to achieve nonreciprocal entanglement characterized by stability and robustness against environmental fluctuations. Here, we propose a universal nonlinear mechanism to engineer magnetic-free nonreciprocity in dissipative optomechanics by utilizing bistability, a phenomenon ubiquitous across nonlinear physical systems. By dynamically encircling the nexus of bistability, a cusp converged by the bistable surfaces, we obtain nonreciprocal displacement and then utilize it to achieve robust nonreciprocal entanglement. Owing to the unique landscape of bistability, our nonreciprocal displacement and entanglements exhibit stability and robustness through closed-loop operations. Our work presents a foundational framework for leveraging nonlinearity to achieve nonreciprocal quantum information processing. It paves new avenues for exploring nonreciprocal quantum information processing and designing backaction-immune quantum metrology with nonlinearity.

The ability to realize unidirectionality and signal amplification in the same device has become an urgent demand, with the increasingly high requirements for integrating signal processing devices. We propose a feasible scheme to achieve amplified unidirectional reflection in a coherent active atomic system via four-wave mixing (FWM) and spontaneously generated coherence (SGC), based on symmetry breaking caused by the spatially linear modulation of coupling on symmetry breaking caused by the spatially linear modulation of coupling fields. Specifically, a narrowed and amplified unidirectional reflection band can be generated in the weak-coupling regime of light- atom interactions with the combination of FWM and SGC, which can be modulated by the relative phase Phi and dipole angle theta. This high and narrow band yields low out-of-band noise, which can prove more advantageous for many on-chip functionalities.

We investigate single-photon scattering in a system comprising a waveguide coupled to a pair of Rydberg atoms, illuminated by a coherent field. By adjusting the interatomic distance, we can transition between the Rydberg blockade and Rydberg antiblockade regimes, as the van der Waals interaction strength varies with distance. These distinct regimes, manifesting in single-photon scattering, allow flexible reflection control due to their analogy to those of small-and giant-atom interactions with the waveguide. We also derive scattering criteria for Rydberg blockade and Rydberg antiblockade, corresponding to specific features in the single-photon reflection spectrum. Based on these criteria, the blockade and antiblockade distances can be estimated.

We introduce two strategies to enhance quantum synchronization within a triple-cavity optomechanical system, where each cavity contains an oscillator and is interconnected via optical fibers. Our results demonstrate that applying appropriate periodic modulation to the driving fields or the cavity modes can ensure robust quantum synchronization across both open and closed configurations. This approach offers promising avenues for expanding quantum synchronization capabilities in multi-cavity systems and has significant implications for advancing quantum synchronization generation and application in complex networks.

In order to achieve the tunable unidirectional reflection amplification in a uniform atomic medium that is of vital importance to design high-quality nonreciprocal photonic devices, we propose a coherent closed three-level Δ-type atomic system by applying a microwave field, and a strong coupling field of linear variation along the x direction to control a probe field. In our scheme, the linearly increased coupling field destroys the spatial symmetry of probe susceptibility and effectively suppresses the reflection of one side; the microwave field constructs closed loop transitions to amplify the probe field and causes phase changes. The numerical simulation indicates that the unidirectional reflection amplification is sensitive to the relative phase ϕ and the coupling detuning Δ c . Our results will open a new route toward harnessing optical non-reciprocity, which can provide more convenience and possibilities in the experimental realization.