Single hole-spin qubit optimization in SOI quantum dots via k⋅p simulations

Spin qubits in semiconductor quantum dots (QDs) are attractive solutions for the implementation of quantum computers. In particular, silicon is a promising host for spin qubits due to long electron/hole spin lifetimes. Additionally, silicon is well suited for integrating quantum devices with classical electronics.

Among the various silicon-based approaches, Silicon-on-Insulator (SOI) is a particularly promising technology. In this approach, quantum information is encoded in the spin of charge carriers confined within quantum dots etched into a thin silicon layer on a SiO₂ substrate. Notably, hole spin qubits offer key advantages over their electron counterparts, primarily owing to their stronger spin–orbit coupling, which enables all-electrical control via electric dipole spin resonance.

In this study, we investigate hole spin qubits in SOI QDs, using the k⋅p model within a COMSOL Multiphysics-based simulation framework. The main purpose is to maximize the Rabi frequency for a given RF drive amplitude through optimal choice of geometry and silicon crystal orientation. The optimization is based on the analysis of the interplay between the symmetry of the hole wavefunction and the orientation of the oscillating electric field. Our results demonstrate that Rabi frequencies up to 1 GHz can be achieved, outperforming previous results in literature.