Room-temperature quantum microwave emitters based on spin defects in silicon carbide

Atomic-scale defects in silicon carbide are always present and usually limit the performance of this material in high-power electronics and radiofrequency communication. Here, we reveal a family of homotypic silicon vacancy defects in silicon carbide exhibiting attractive spin properties. In particular, the defect spins can be initialized and read out even at room temperature by means of optically detected magnetic resonance, suggesting appealing applications such as spin qubits and spin magnetometers. Using this technique we detect two-quantum spin resonances, providing strong evidence for the S = 3/2 ground state of the silicon vacancy defects. The optically induced population inversion of these high-spin ground states leads to stimulated microwave emission, which we directly observed in our silicon carbide crystals. The analysis based on the experimentally obtained parameters shows that this property can be used to implement solid-state masers and extraordinarily sensitive radiofrequency amplifiers.