An analysis of spin orbit effects on spin dependent tunnel coupling and g-factor tuning in double quantum dots

Self-assembled quantum dots have been sought as semiconductor qubit architecture due to their optical addressability and electrical tunability. Double dot systems have the additional tunability of electrically biasing the two dots in and out of energetic resonance. During resonance, the tunnel coupling strength between the two dots depends on the orientation of the spin state, which, in turn, modifies the effective g-factor of the states. The physical mechanism driving spin-dependent tunneling and the change in effective g-factor has not been well studied. We present results obtained with an atomistic tight-binding model and perturbative analysis of the tight-binding wavefunctions to show that the change in g-factor during resonance arises solely from inclusion of the Peierls contribution. In contrast, the other two magnetic field terms, namely, the spin and atomic orbital contributions do not contribute to the resonance behavior of the g-factor or exhibit and other resonance behavior. Additionally, we contrast electron and holes states, with and without spin-orbit terms in the Hamiltonian, to demonstrate the spin-orbit nature of resonance g-factor tuning.