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

TL;DR

This paper proposes a method to suppress electron spin decoherence caused by inhomogeneous microwave fields in EPR experiments by using a weak radiofrequency field at Rabi resonance, enhancing spin coherence.

Contribution

It introduces a novel spin state dressing technique with a radiofrequency field to mitigate inhomogeneity-induced decoherence in Rabi oscillations.

Findings

Maximum decoherence suppression occurs at Rabi resonance.

The method is effective without phase matching and for various inhomogeneity types.

Potential to distinguish relaxation mechanisms from inhomogeneous effects.

Abstract

The decay of Rabi oscillations provides direct information about coherence of electron spins. When observed in EPR experiments, it is often shortened by spatial inhomogeneity of the microwave field amplitude in a bulk sample. In order to suppress this undesired loss of coherence, we propose an additional dressing of spin states by a weak longitudinal continuous radiofrequency field. Our calculations of the Rabi oscillations between the doubly dressed spin states show that the maximum suppression of decoherence is achieved at the so-called Rabi resonance when the radio-field frequency is in resonance with the Rabi frequency of spins in the microwave field. This effect is feasible even in the absence of phase matching in the radiofrequency field and for different types of inhomogeneity of the microwave field. The manifestations of such suppression in the published EPR experiments with the bichromatic driving are discussed. The realization of the Rabi resonance using the radiofrequency field could open new possibilities for separating the contributions of relaxation mechanisms from those due to the inhomogeneous driving in spin decoherence.