Measurement of spin coherence using Raman scattering

Abstract

Measuring spin coherence time is essential in general characterization of a qubit. Here, a novel method to determine the coherence time of a spin qubit is implemented, based on the coherence properties of inelastic Raman scattering obtained with an unbalanced Mach-Zehnder interferometer. The authors demonstrate this method on both a single electron spin and a hole spin confined in a self-assembled quantum dot. The visibility of the first-order coherence of Raman scattered photon in the weak excitation regime exhibits a Gaussian decay as a function of the time delay, allowing a direct extraction of ${T}_{2}^{*}$, which is immune to the limitations that influence standard Ramsey interference with self-assembled quantum dots.