Dynamic current susceptibility as a probe of Majorana bound states in nanowire-based Josephson junctions

TL;DR

This paper introduces a theoretical method to detect Majorana bound states in nanowire Josephson junctions by analyzing their dynamic susceptibility, revealing a dominant diagonal component linked to Majorana state populations.

Contribution

It develops a density matrix approach to calculate flux-dependent susceptibility, highlighting a new diagonal term as an effective probe of Majorana states in nanowire junctions.

Findings

Diagonal susceptibility component dominates over Kubo contribution.

Diagonal term effectively indicates presence of Majorana bound states.

Method applicable to experimentally relevant parameters.

Abstract

We theoretically study a Josephson junction based on a semiconducting nanowire subject to a time-dependent flux bias. We establish a general density matrix approach for the dynamical response of the Majorana junction and calculate the resulting flux-dependent susceptibility using both microscopic and effective low-energy descriptions for the nanowire. We find that the diagonal component of the susceptibility, associated with the dynamics of the Majorana states populations, dominates over the standard Kubo contribution for a wide range of experimentally relevant parameters. The diagonal term, thus far unexplored in the context of Majorana physics, allows to probe accurately the presence of Majorana bound states in the junction.