Unconventional Josephson signatures of Majorana bound states

TL;DR

This paper discusses unique Josephson effects arising from Majorana bound states in topological superconductor junctions, highlighting a novel fractional effect that can serve as a signature for Majorana modes.

Contribution

It introduces a new fractional Josephson effect caused by spatially separated Majoranas, providing a distinctive experimental signature for detecting Majorana bound states.

Findings

Identification of a new fractional Josephson effect due to Majorana separation

Prediction of unique Shapiro steps as signatures of Majorana modes

Enhanced understanding of Josephson effects in topological superconductors

Abstract

A junction between two topological superconductors containing a pair of Majorana fermions exhibits a `fractional' Josephson effect, $4\pi$ periodic in the superconductors' phase difference. An additional fractional Josephson effect, however, arises when the Majoranas are spatially separated by a superconducting barrier. This new term gives rise to a set of Shapiro steps which are essentially absent without Majorana modes and therefore provides a unique signature for these exotic states.