Improving the tight-binding description of spin-orbit interaction in a Si/Ge heterostructure for qubits applications

Hole spin qubits realized in Ge heterostructures are a promising quantum computing platform. An accurate description of spin-orbit effects is mandatory in numerical methods for device modelling, such as Tight-Binding, to properly describe the spin physics. This work presents a methodology to improve the spin-orbit interaction in Tight-Binding, and to match reference ab initio results. We apply this methodology to a prototypical Si/Ge heterostructure, and we achieve such improvement by tuning the Si/Ge band alignment and the onsite potential of the interface atoms, which indicates that the confinement potential is the primary factor for the accurate description of spin-orbit interaction.