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The negatively charged tin-vacancy center in diamond ( ${\mathrm{SnV}}^{-}$) is an emerging platform for building the next generation of long-distance quantum networks. This is due to the ${\mathrm{SnV}}^{-}$’s favorable optical and spin properties including bright emission, insensitivity to electronic noise, and long spin coherence times at temperatures above 1 K. Here, we demonstrate measurement of a single ${\mathrm{SnV}}^{-}$electronic spin with a single-shot readout fidelity of 87.4%, which can be further improved to 98.5% by conditioning on multiple readouts. In the process, we develop understanding of the relationship between strain, magnetic field, spin readout, and microwave spin control. We show that high-fidelity readout is compatible with rapid microwave spin control, demonstrating a favorable parameter regime for use of the ${\mathrm{SnV}}^{-}$center as a high-quality spin-photon interface. Finally, we use weak quantum measurement to study measurement-induced dephasing; this illuminates the fundamental interplay between measurement and decoherence in quantum mechanics, and provides a universal method to characterize the efficiency of color-center spin readout. Taken together, these results overcome an important hurdle in the development of the ${\mathrm{SnV}}^{-}$-based quantum technologies and, in the process, develop techniques and understanding broadly applicable to the study of solid-state quantum emitters. Published by the American Physical Society2024 

Integrating solid-state quantum emitters with photonic circuits is essential for realizing large-scale quantum photonic processors. Negatively charged tin-vacancy (SnV−) centers in diamond have emerged as promising candidates for quantum emitters because of their excellent optical and spin properties, including narrow-linewidth emission and long spin coherence times. SnV− centers need to be incorporated in optical waveguides for efficient onchip routing of the photons they generate. However, such integration has yet to be realized. In this Letter, we demonstrate the coupling of SnV− centers to a nanophotonic waveguide. We realize this device by leveraging our recently developed shallow ion implantation and growth method for the generation of high-quality SnV− centers and the advanced quasi-isotropic diamond fabrication technique. We confirm the compatibility and robustness of these techniques through successful coupling of narrow-linewidth SnV− centers (as narrow as 36 ± 2 MHz) to the diamond waveguide. Furthermore, we investigate the stability of waveguide-coupled SnV− centers under resonant excitation. Our results are an important step toward SnV−-based on-chip spin-photon interfaces, single-photon nonlinearity, and photon-mediated spin interactions.