Single-Shot Readout and Weak Measurement of a Tin-Vacancy Qubit in Diamond

The negatively charged tin-vacancy center in diamond (SnV^{-}) is an emerging platform for building the next generation of long-distance quantum networks. This is due to the 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 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 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 SnV^{-}-based quantum technologies and, in the process, develop techniques and understanding broadly applicable to the study of solid-state quantum emitters.