Purcell enhancement of a single T center in a silicon nanophotonic cavity*

Optically addressable atomic defects in solids are promising building blocks for future quantum communication technologies. The silicon-on-insulator (SOI) platform is an ideal host for such defects as it benefits from technologically mature silicon photonics and electronics. The novel T center in silicon offers telecommunication O-band optical transitions as well as a doublet ground state spin manifold with a long coherence time, making it a prime candidate for building quantum repeater devices. However, T centers’ weak coherent zero phonon line (ZPL) emission rate stands as an obstacle to their use in quantum networking applications. Here, by integrating single T centers with a low-loss, small mode-volume photonic crystal cavity on SOI, we demonstrate cavity-enhanced fluorescence emission from a single T center with an enhancement factor up to F = 6.89. Leveraging nanophotonic circuits and an angle-polished fiber for light coupling, the system achieves efficient ZPL photon extraction reaching an average outcoupling rate of 73.3 kHz. Lastly, by solving the Lindblad master equation, we extract the T-center-cavity coupling parameters and elucidate the cavity quantum electrodynamics of the coupled system. This work represents a major step towards utilizing single T centers in silicon for quantum information processing and networking applications.