Anomalous Josephson effect in semiconducting nanowires as a signature of the topologically nontrivial phase

TL;DR

This paper investigates how the anomalous Josephson effect in semiconducting nanowire-based junctions can serve as an indicator of topologically nontrivial superconducting phases, with potential implications for quantum computing.

Contribution

It demonstrates that tuning nanowires into the helical regime enhances the anomalous Josephson current, providing a new signature of topological superconductivity.

Findings

Large anomalous current indicates topologically nontrivial phase

Tuning into the helical regime significantly increases the anomalous current

Short junctions show clear signatures of topological superconductivity

Abstract

We study Josephson junctions made of semiconducting nanowires with Rashba spin-orbit coupling, where superconducting correlations are induced by the proximity effect. In the presence of a suitably directed magnetic field, the system displays the anomalous Josephson effect: a nonzero supercurrent in the absence of a phase bias between two superconductors. We show that this anomalous current can be increased significantly by tuning the nanowire into the helical regime. In particular, in a short junction, a large anomalous current is a signature for topologically nontrivial superconductivity in the nanowire.