Isotropic and Anisotropic g-factor Corrections in GaAs Quantum Dots*

The spin splitting is a fundamental property of an electron confined in a semiconductor in an external magnetic field and sets the qubit energy – a key parameter for quantum computation. Here, we experimentally determine isotropic and anisotropic g-factor corrections in lateral GaAs single-electron quantum dots (Camenzind, Svab et al., arXiv:2010.11185 (2020)). We extract Zeeman splittings by measuring tunnel rates into individual spin states of an empty quantum dot for various in-plane magnetic field strengths/directions. We find an anisotropic correction of ≈7% of the average g-factor, in good agreement with recent theory (Stano et al. PRB98, 195314 (2018)), where this is due to Dresselhaus spin-orbit interaction (SOI) using a coefficient of 10.6 eVų. The isotropic correction is measured to reduce the average g-factor 10-15% below the bulk value |g|=0.44, due to Rashba SOI and an additional ''43-term'' SOI. These corrections are predicted to depend strongly on the thickness of the wave function in the z-direction perpendicular to the 2D gas. These findings provide the fundamental physics of the single-electron spin splitting and as such are at the heart of GaAs spin qubits.