All-Optical Spin Initialization via a Cavity Broadened Optical Transition in On-Chip Hybrid Quantum Photonics

Hybrid quantum photonic systems connect classical photonics to the quantum world and promise to deliver efficient light-matter quantum interfaces while leveraging the advantages of both, the classical and the quantum, subsystems. However, combining efficient, scalable photonics and solid state quantum systems with desirable optical and spin properties remains a formidable challenge. In particular the access to individual spin states and coherent mapping to photons remains unsolved for these systems. In this letter, we demonstrate all-optical initialization and readout of the electronic spin of a negatively-charged silicon-vacancy center in a nanodiamond coupled to a silicon nitride photonic crystal cavity. We characterize relevant parameters of the coupled emitter-cavity system and determine the silicon-vacancy center's spin-relaxation and spin-decoherence rate. Our results mark an important step towards the realization of a hybrid spin-photon interface based on silicon nitride photonics and the silicon-vacancy center's electron spin in nanodiamonds with potential use for quantum networks, quantum communication and distributed quantum computation.