Theory of Optically Detected Magnetic Resonance of a Silicon Vacancy in Silicon Carbide: A Quantum Sensor of Magnetic Fields

David Fehr; University of Iowa

Silicon carbide (SiC) devices have generated significant interest in the spaceflight industry because of their ability to operate at high temperatures and voltages, due to the wide bandgap and high breakdown electric field strength of SiC, while also having a low size, weight, and power (SWaP) rating. SiC also exhibits an intrinsic resistance to damage from irradiation and hosts localized, atomic-scale defects within the lattice which have potential for quantum sensing applications. One of the most popular atomic-scale defects in SiC for quantum sensing applications is the negatively charged silicon vacancy (V_Si—). V_Si— can be modeled as a synthetic atom with localized spin states that are sensitive to magnetic fields, and its quantum spin dynamics can be read out optically. This makes V_Si— an attractive choice for optically detected magnetic resonance (ODMR) spectroscopy, as its optical response to magnetic fields generates a characteristic and reproducible reference curve. In ODMR, traditional electron spin resonance is combined with a laser resonant on the transition between the ground and first excited state for an optical readout of coherent spin dynamics. In this talk we introduce the foundations of magnetic resonance and ODMR spectroscopies, and show our simulated ODMR spectra of V_Si— in SiC using Lindblad equations and density matrix populations. Furthermore, by fitting our results to experimental data we show how spin Hamiltonian parameters, transition rates, and coherence times may be constrained to inform future experimental designs.