Tailoring the Superconductor-Semiconductor Hybridization in Majorana Devices

Recent experiments have provided solid evidence of Majorana quasiparticles in hybrid superconductor-semiconductor (Super-Semi) devices. However, the desired exploitation of Majoranas for quantum manipulations requires a high-degree of device-controllability and -tunability. More importantly, vital aspects of the Super-Semi hybridization which controls the above features, still remain unexplored. In this work, we employ a self-consistent Schrödinger-Poisson (SP) approach for addressing these key issues for Al-InAs interfaces. We obtain the electrostatic potential and the bandstructure via a numerical finite-difference self-consistent SP-method, using experimentally inferred parameters as an input. We also infer the band-resolved: (i) hybridization degree, (ii) Landé g-factor and (iii) Rashba spin-orbit coupling strength. We reveal that the interface coupling not only modifies the preexisting InAs levels, but most importantly, it gives rise to a new band near the Fermi level, solely due to the Al-InAs hybridization. We discuss how to tune the bandstructure characteristics via varying the width of the Al-layer, as also the backgate-voltage. Our numerical analysis is backed by an analytical approach, elucidating further aspects of the hybridization.