Photonic indistinguishability characterization and optimization for cavity-based single-photon source

Indistinguishability of single photons from independent sources is critically important for scalable quantum technologies. We provide a comprehensive comparison of single-photon indistinguishability of different kinds of cavity quantum electrodynamics (CQED) systems by numerically simulating Hong-Ou-Mandel (HOM) two-photon interference. We find that the CQED system using natural atoms exhibits superiority in indistinguishability, benefiting from the inherently identical features. Moreover, a Λ−type three-level atom shows essential robustness against variation of various system parameters because it exploits the two ground states with considerably smaller decay rates for single-photon generation. Furthermore, a machine learning-based framework is proposed to significantly and robustly improve single-photon indistinguishability for two non-identical CQED systems. This work may pave the way for designing and engineering reliable and scalable photon-based quantum technologies.