Electric-dipole spin resonance for light-holes in germanium quantum well

Holes in Germanium (Ge) quantum wells (QW) have recently attracted a great deal of attention due to their numerous attractive properties for the realization of quantum processors. In contrast to electrons, holes are affected significantly by the large spin-orbit coupling in Ge, enabling fast all-electrical spin-manipulation schemes such as electric-dipole spin resonance (EDSR). A novel type of two-dimensional hole gas consisting of light-holes can be achieved by applying a significant amount of tensile train (>1%) to the QW. A light-hole based quantum device also benefits of a more efficient photon-to-spin interface. This work discusses the properties of light-hole spins in highly tensile strained Ge QWs, whose strain is caused by coherent growth onto highly relaxed germanium-tin buffer layers. A perturbative framework describing Rabi-flopping of a light hole spin in a parabolic isotropic gate-defined quantum dot is derived from 8-band k·p theory. A quantitative analysis of the Rabi frequency versus physical parameters shows that light-holes can be manipulated 2 to 3 orders of magnitude faster than heavy-holes. The framework explicitly takes in account the spread of the envelope wavefunctions into the barriers and is suitable for any out-of-plane confining potential.