Quantum metrology with a single spin-3/2 defect in silicon carbide

We show that implementations for quantum sensing with exceptional sensitivity and spatial resolution can be made using the novel features of semiconductor high half-spin multiplet defects with easy-to-implement optical detection protocols. To achieve this, we use the spin-$3/2$ silicon monovacancy deep center in hexagonal silicon carbide based on our rigorous derivation of this defect's ground state and of its electronic and optical properties. For a single $\textrm{V}_{\textrm{Si}}^-$ defect, we obtain magnetic field sensitivities capable of detecting individual nuclear magnetic moments. We also show that its zero-field splitting has an exceptional strain and temperature sensitivity within the technologically desirable near-infrared window of biological systems. Other point defects, i.e. 3d transition metal or rare-earth impurities in semiconductors, may also provide similar opportunities in quantum sensing due to their similar high spin ($S\geq 3/2$) configurations.