Purcell-Enhanced T Centers in Bus-Coupled Cavity Arrays

Color centers in silicon have emerged as promising candidates for building photonic quantum processors. Among these color centers, the T center's long spin lifetime makes it an attractive platform for realizing quantum repeater nodes at scale due to its compatibility with silicon fabrication and telecom-band emission. However, the T center's long optical lifetime, broad single-emitter linewidth, and lack of optical cycling transitions all present challenges in realizing an efficient quantum repeater node. While cavity enhancement through the Purcell effect can shorten the optical lifetime and increase the cyclicity of a transition, achieving a high yield of bright cavity-enhanced T centers remains a challenge. In this work, we introduce a novel device platform consisting of arrays of 1D photonic crystal cavities (PCCs) evanescently coupled to a common single-mode bus waveguide. We develop an iterative feedback-based tuning method in this platform based on the global deposition and cavity-selective removal of a thin film of nitrogen on the device. Using this method, we achieve programmable cavity resonance tuning with picometer-level precision. We leverage the tunability and connectivity of our platform to align two cavities with their T centers, and demonstrate parallel operation of two spatially and spectrally separated cavity-enhanced T centers through a single waveguide. Using a random-access laser capable of switching between the T center wavelengths in < 2 μs, we multiplex single photons from the T centers, and confirm high quality single-photon emission from both by measuring intensity correlations. Finally, we demonstrate the enhancement of a single T center by a hybridized cavity mode formed between two spatially distinct cavities, and present a theoretical model of the hybridization dynamics in the device. Our work reveals a path to realizing bus waveguide-mediated interactions between distant T centers and multiplexed entanglement generation in a scalable architecture.