Suppression of electron spin decoherence in Rabi oscillations induced by an inhomogeneous microwave field

摘要

The decay of Rabi oscillations provides direct information about coherence ofelectron spins. When observed in EPR experiments, it is often shortened byspatial inhomogeneity of the microwave field amplitude in a bulk sample. Inorder to suppress this undesired loss of coherence, we propose an additionaldressing of spin states by a weak longitudinal continuous radiofrequency field.Our calculations of the Rabi oscillations between the doubly dressed spinstates show that the maximum suppression of decoherence is achieved at theso-called Rabi resonance when the radio-field frequency is in resonance withthe Rabi frequency of spins in the microwave field. This effect is feasibleeven in the absence of phase matching in the radiofrequency field and fordifferent types of inhomogeneity of the microwave field. The manifestations ofsuch suppression in the published EPR experiments with the bichromatic drivingare discussed. The realization of the Rabi resonance using the radiofrequencyfield could open new possibilities for separating the contributions ofrelaxation mechanisms from those due to the inhomogeneous driving in spindecoherence.