Electric field tunable superconductor-semiconductor coupling in Majorana nanowires

TL;DR

This study demonstrates how external electric fields can tune superconductor-semiconductor coupling in Majorana nanowires, affecting key properties like the superconducting gap and spin-orbit coupling, and highlights potential challenges in identifying Majorana zero modes.

Contribution

It provides experimental insights into electric field control of superconductor-semiconductor coupling and its impact on Majorana nanowire properties, advancing understanding of Majorana physics.

Findings

Electric fields significantly modify coupling strength.

Level repulsion can mimic Majorana zero modes.

Electric tuning affects superconducting gap and spin-orbit coupling.

Abstract

We study the effect of external electric fields on superconductor-semiconductor coupling by measuring the electron transport in InSb semiconductor nanowires coupled to an epitaxially grown Al superconductor. We find that the gate voltage induced electric fields can greatly modify the coupling strength, which has consequences for the proximity induced superconducting gap, effective g-factor, and spin-orbit coupling, which all play a key role in understanding Majorana physics. We further show that level repulsion due to spin-orbit coupling in a finite size system can lead to seemingly stable zero bias conductance peaks, which mimic the behavior of Majorana zero modes. Our results improve the understanding of realistic Majorana nanowire systems.