Hard gap in epitaxial semiconductor-superconductor nanowires

TL;DR

This paper demonstrates a hard superconducting gap in epitaxial Al-InAs nanowires, enabling better control and potential for topological quantum computing applications.

Contribution

It reports the first realization of a hard superconducting gap in epitaxial semiconductor-superconductor nanowires, improving prospects for topological quantum devices.

Findings

Hard gap observed in epitaxial Al-InAs nanowires

Enhanced material properties and gate-tunability

Potential for topological quantum computing

Abstract

Many present and future applications of superconductivity would benefit from electrostatic control of carrier density and tunneling rates, the hallmark of semiconductor devices. One particularly exciting application is the realization of topological superconductivity as a basis for quantum information processing. Proposals in this direction based on proximity effect in semiconductor nanowires are appealing because the key ingredients are currently in hand. However, previous instances of proximitized semiconductors show significant tunneling conductance below the superconducting gap, suggesting a continuum of subgap states---a situation that nullifies topological protection. Here, we report a hard superconducting gap induced by proximity effect in a semiconductor, using epitaxial Al-InAs superconductor-semiconductor nanowires. The hard gap, along with favorable material properties and gate-tunability, makes this new hybrid system attractive for a number of applications, as well as fundamental studies of mesoscopic superconductivity.