Multipartite Einstein-Podolsky-Rosen (EPR) steering admits multipartite entanglement in the presence of uncharacterized verifiers, enabling practical applications in semi-device-independent protocols. Such applications generally require stronger steerability, while the unavoidable noise weakens steerability and consequently degrades the performance of quantum information processing. Here, we propose the local filtering operation that can maximally distill genuine tripartite EPR steering from N copies of three-qubit generalized Greenberger-Horne-Zeilinger states, in the context of two semi-device-independent scenarios. The optimal filtering operation is determined by the maximization of assemblage fidelity. Analytical and numerical results indicate the advantage of the proposed filtering operation when N is finite and the steerability of initial assemblages is weak. Experimentally, a proof-of-principle demonstration of two-copy distillation is realized with the optical system. The advantage of the optimal local filtering operation is confirmed by the distilled assemblage in terms of higher assemblage fidelity with perfectly genuine tripartite steerable assemblages, as well as the greater violation of the inequality to witness genuine tripartite steerable assemblages. Our results benefit the distillation of multipartite EPR steering in practice, where the number of copies of initial assemblages is generally finite.

Fiber scanners are portable and miniaturized laser scanning devices used for a wide range of applications, such as endoscopic probes for biomedical imaging. However, in order to achieve different resonant frequencies for 2D actuation, existing fiber scanners have complex actuation mechanisms and structures, resulting in being an obstacle for endoscopic imaging. By exploiting the intrinsic difference in bending stiffness of non-symmetrical fibers, we present the most simplified fiber scanner to date, containing only a single piezoelectric bimorph and a single non-symmetrical fiber with a 1D actuator for 2D laser scanning. 5-fps (frames per second) Lissajous scan is achieved with a scanning range of >300μm and a driving voltage of ≤10Vpp. The ultra simplified structure of the fiber scanner enables a miniaturized optical probe with a diameter of 1.9 mm, and image quality comparable to that of commercial microscopes. Taking advantage of its ease of manufacture and low cost, the fiber scanner offers a transformative way forward for disposable endoscopic probes that avoid the risk of cross infection during endoscopic inspections.

The realization of robust coherent energy transfer with a long range from a donor to an acceptor has many important applications in the field of quantum optics. However, it is hard to be realized using conventional schemes. Here, we demonstrate theoretically that robust energy transfer can be achieved using a photonic crystal platform, which includes the topologically protected edge state and zero-dimensional topological corner cavities. When the donor and the acceptor are put into a pair of separated topological cavities, the energy transfer between them can be fulfilled with the assistance of the topologically protected interface state. Such an energy transfer is robust against various kinds of defects, and can also occur over very long distances, which is very beneficial for biological detections, sensors, quantum information science, and so on.