High-Efficiency Single Photon Emission from a Silicon T-Center in a Nanobeam

Color centers in Si could serve as both efficient quantum emitters and quantum memories with long coherence times in an all-silicon platform. Of the various known color centers, the T-center holds particular promise because it possesses a spin ground state that has long coherence times, but this color center exhibits a long excited state lifetime that results in a low-photon emission rate, requiring methods to extract photon emission with high efficiency. We demonstrate high-efficiency single-photon emission from a single T-center using a nanobeam. The nanobeam efficiently radiates light in a mode that is well-matched to a lensed fiber, enabling us to couple over 70% of the photons in the nanobeam directly into a single-mode fiber. This efficiency enables us to directly demonstrate single-photon emission from the zero-phonon line, which represents the coherent emission from the T-center. Our results represent an important step toward silicon-integrated spin–photon interfaces for quantum computing and quantum networks.