G-factor Anisotropy of a Single Electron in a GaAs Quantum Dot*

Spins in semiconductor quantum dots are among the leading candidates for quantum computing. To lift spin degeneracy, a large in-plane magnetic field is applied. This has sizable effects on the confined electron, allowing the shape and orientation of the orbitals to be inferred in this way, see Camenzind et al. PRL112, 207701 (2019).
Here, we present experiments studying the effect of the strength and direction of in-plane magnetic fields on the spin structure of an electron in a gated GaAs quantum dot. We have measured an anisotropic correction of about 7% and an isotropic correction pushing the average g-factor 10-15% below the bulk value |g|=0.44. The experiment is compared to theory by Stano et al. PRB98, 195314 (2018), finding rather good agreement. The anisotropic correction is given by the Dresselhaus spin-orbit coupling, matching well using a coefficient of 10.6 eVÅ. The isotropic term is dominated by the well-known Rashba term and an additional 43-term appearing in finite B-field. These corrections are predicted to depend strongly on the thickness of the wave function in the z-direction perpendicular to the 2D gas, and may also depend on the strength of the in-plane field.