Tunable Supercurrent Through Semiconductor Nanowires

TLDR

Hybrid devices combine indium arsenide nanowires with aluminum superconducting contacts to form nanoscale superconductor/semiconductor structures. At temperatures below 1 K, highly transparent contacts induce superconductivity in the nanowires, forming mesoscopic Josephson junctions whose coupling can be tuned electrically. Gate voltage controls the supercurrent, producing on/off switching, correlated conductance fluctuations, and Shapiro steps under microwave irradiation.

Abstract

Nanoscale superconductor/semiconductor hybrid devices are assembled from indium arsenide semiconductor nanowires individually contacted by aluminum-based superconductor electrodes. Below 1 kelvin, 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 alternating-current Josephson effect gives rise to Shapiro steps in the voltage-current characteristic under microwave irradiation.