  Atomic defects in solid-state materials are promising candidates for quantum
interconnect and networking applications. Recently, a series of atomic defects
have been identified in the silicon platform, where scalable device integration
can be enabled by mature silicon photonics and electronics technologies. In
particular, T centers hold great promise due to their telecom band optical
transitions and the doublet ground state electronic spin manifold with long
coherence times. However, an open challenge for advancing the T center platform
is to enhance its weak and slow zero phonon line emission. In this work, we
demonstrate the cavity-enhanced fluorescence emission from a single T center.
This is realized by integrating single T centers with a low-loss, small
mode-volume silicon photonic crystal cavity, which results in an enhancement of
the fluorescence decay rate by a factor of $F$ = 6.89. Efficient photon
extraction enables the system to achieve an average photon outcoupling rate of
73.3 kHz at the zero phonon line. The dynamics of the coupled system is well
modeled by solving the Lindblad master equation. These results represent a
significant step towards building efficient T center spin-photon interfaces for
quantum information processing and networking applications.
