Optimizing spin-orbit splittings in InSb Majorana nanowires

Semiconductor-superconductor heterostructures represent a promising platform for the detection of Majorana zero modes and subsequently the processing of quantum information using their exotic non-Abelian statistics. Theoretical modeling of such low-dimensional heterostructures is generally based on phenomenological effective models. However, a more microscopic understanding of the band structure and, especially, of the spin-orbit coupling of electrons in these devices is important for optimizing their parameters for applications in quantum computing. In this paper, we approach this problem by first obtaining a highly accurate effective tight-binding model of bulk InSb from ab initio calculations. This model is symmetrized and correctly reproduces both the band structure and the wavefunction character. It is then used to simulate slabs of InSb in external electric fields. The results of this simulation are used to determine a growth direction for InSb nanowires that optimizes the conditions for the experimental realization of Majorana zero modes.