Solid-state spin defects are promising qubits for quantum network nodes. A key challenge toward larger networks is creating defects with high yield into nanophotonic devices while maintaining good optical and spin properties. Here, we demonstrate the creation of single V2 centers in nanopillars fabricated from commercial bulk-grown 4H-silicon carbide using a pulsed above-bandgap (UV) laser. We observe an 11-fold increase in the V2 center occurrence after UV laser illumination. These laser-induced V2 centers exhibit narrow optical line widths and spectral diffusion rates comparable to naturally occurring V2 centers in nanopillars of the same material. Furthermore, we measure a spin coherence time of (Formula presented) under dynamical decoupling, consistent with dephasing by the nuclear-spin bath. This demonstration of the in situ, postfabrication generation of coherent V2 centers in nanostructures in widely available bulk-grown 4H-SiC shows the potential for above-bandgap laser illumination for scalable defect creation in integrated photonic devices.

We demonstrate coherent coupling of a single diamond Tin-Vacancy center to a fiber-based microcavity, showing a cavity transmission dip of 50 % on resonance, and altered photon statistics in cavity transmission.

Open microcavities offer great potential for the exploration and utilization of efficient spin-photon interfaces with Purcell-enhanced quantum emitters thanks to their large spectral and spatial tunability combined with high versatility of sample integration. However, a major challenge for this platform is the sensitivity to cavity length fluctuations in the cryogenic environment, which leads to cavity resonance frequency variations and thereby a lowered averaged Purcell enhancement. This work presents a closed-cycle cryogenic fiber-based microcavity setup, which is in particular designed for a low passive vibration level, while still providing large tunability and flexibility in fiber and sample integration, and high photon collection efficiency from the cavity mode. At temperatures below 10 K, a stability level of around 25 pm is reproducibly achieved in different setup configurations, including the extension with microwave control for manipulating the spin of cavity-coupled quantum emitters, enabling a bright photonic interface with optically active qubits.

We show diamond Tin-Vacancy centers, coherently-coupled to a tunable microcavity. The exceptional optical properties of this emitter in combination with a stable, high quality cavity enables a cavity transmission signal modulated by a single emitter.