Measurement of spin relaxation time in InGaAs double quantum dots

A proposed spin qubit consists of a single electron residing in a material of selected electron g-factor. For successful implementation the spin relaxation time, T$_{1}$, must be sufficiently long to enable multiple operations. Previously, double quantum dots (DQD) have been used for the detection of spin states. We report measurements of T$_{1}$ in a DQD in In$_{x}$Ga$_{1-x}$As (x = 0.1, 0.2) with g-factors of $\approx$ -0.9 and -1.6 respectively, displaying larger spin-orbit (SO) coupling effects. DQDs are measured in the Pauli spin blockade regime using RF charge detection techniques. Using high frequency pulses applied to electrostatically defined gates T$_{1}$ is calculated from resulting visibility of the triplet spin state. Magnetic field probes the effect of the SO compared to the hyperfine interaction on T$_{1}$. With larger g-factor, splitting of the singlet-triplet energy levels, so supressing hyperfine-mediated relaxation, occurs at comparatively smaller magnetic field and may compensate for increased SO effects. Thus T$_{1}$ in InGaAs is shown to be sufficient for quantum computation applications.