Microwave spectroscopy of Josephson junctions in topological superconductors

TL;DR

This paper explores microwave spectroscopy of Josephson junctions with Majorana states in topological superconductors, revealing how microwave signals can probe the 4π Josephson effect and switch Shapiro steps.

Contribution

It introduces a method to directly detect the nonequilibrium 4π Josephson effect using microwave driving in topological superconductors.

Findings

Microwave spectroscopy reveals features of Majorana-based Josephson junctions.

Microwave driving can switch between 4π and 2π Shapiro steps.

Proposes a way to probe nonequilibrium states in topological superconductors.

Abstract

We consider microwave spectroscopy of Josephon junctions composed of hybridized Majorana states in topological 1-D superconductors. We point out how spectroscopic features of the junction appear in the current phase relation under microwave irradiation. Moreover, we discuss a way to directly probe the nonequilibrium state associated with the 4{\pi} periodic Josephson effect. In particular, we show how the microwave driving can be used to switch from a 4{\pi} to a 2{\pi} Shapiro step in the current voltage relation.