Strong Coupling Between in-Fiber Microcavity and Single Quantum Emitter for Long-Distance Quantum Communication

High-performance single-photon sources (SPSs) are essential components for quantum information technology and have been realized by strong coupling between a single quantum emitter and an optical cavity. However, the configurations of conventional SPSs are not ideal for long-distance quantum communication as they are intrinsically incompatible with optical fibers. Here we propose and design a strong-coupling system based on a single quantum emitter directly coupled with an in-fiber microcavity. The in-fiber microcavity not only achieves a high coupling efficiency of 83% and a high Purcell factor of 360, but also pushes the coupling system to enter the strong-coupling region with a vacuum Rabi splitting up to 4.35 meV. This enables a high quantum efficiency of 99% for a SPS. Our work presents a promising platform for realizing high-performance SPSs for long-distance quantum communication.