Tunable Supercurrent Through Semiconductor Nanowires

TL;DR

This paper demonstrates tunable supercurrent in semiconductor nanowires with high contact transparency, enabling control of superconducting states via gate voltage and revealing conductance fluctuations correlated with critical current variations.

Contribution

It introduces a method to electrically tune supercurrent in InAs nanowire-based Josephson junctions, highlighting the relationship between conductance fluctuations and supercurrent.

Findings

Supercurrent can be switched on and off with gate voltage.

Conductance fluctuations are correlated with critical current fluctuations.

Shapiro steps observed under microwave irradiation.

Abstract

Nanoscale superconductor-semiconductor hybrid devices are assembled from InAs semiconductor nanowires individually contacted by aluminum-based superconductor electrodes. Below 1 K, the high transparency of the contacts gives rise to proximity-induced superconductivity. The nanowires form superconducting weak links operating as mesoscopic Josephson junctions with electrically tunable coupling. The supercurrent can be switched on/off by a gate voltage acting on the electron density in the nanowire. A variation in gate voltage induces universal fluctuations in the normal-state conductance which are clearly correlated to critical current fluctuations. The ac Josephson effect gives rise to Shapiro steps in the voltage-current characteristic under microwave irradiation.