Device specific modelling of hole spin qubits in realistic devices: A Multi-Scale and Multiphysics approach

Hole qubits have attracted significant interest due to their strong spin-orbit coupling (SOC), which enables fast, all electrical control via Electric Dipole Spin Resonance (EDSR). Hole quantum dots are multi-band systems with strong quantum confinement and intricate SOC, influenced by device specific details like strain, interface and disorder. Thermal strain from the metal gates at cryogenic temperatures and the electrostatic environment created by the device specific gate layout affects the qubit properties. Thus, a device specific approach is essential. This work employs the atomistic tight-binding (TB) method, a full-band, full-Brillouin Zone method that captures atomistic granularity and disorder from atomic locations and species. SOC falls out naturally from the atomically constructed latices and interfaces, without requiring additional symmetry constraints or assumptions. We incorporate continuum elastic theory with accurate finite-element modelling (FEM) to capture the thermal strain at cryogenic temperatures. The qubit’s electrostatic environment is also calculated using FEM. Strain is translated into atomic displacements, and voltages are mapped to the atomic locations within the silicon lattice. The electronic structure is then calculated in the TB framework. We explore how gate material, disorder and confinement affect the g tensor, showing good agreement with recent experimental g-factor data.