Quasiparticle poisoning in trivial and topological Josephson junctions

TL;DR

This paper theoretically investigates how quasiparticle poisoning affects voltage signals in trivial and topological Josephson junctions, providing a method to distinguish between different quantum states and measure poisoning rates.

Contribution

It introduces a novel approach to differentiate trivial and topological phases via voltage signatures caused by quasiparticle poisoning in Josephson junctions.

Findings

Voltage signatures differ significantly between trivial and topological phases.

These signatures enable distinguishing between Andreev and Majorana bound states.

The method allows direct measurement of quasiparticle poisoning rates.

Abstract

We study theoretically a short single-channel Josephson junction between superconductors in the trivial and topological phases. The junction is assumed to be biased by a small current and subjected to quasiparticle poisoning. We find that the presence of quasiparticles leads to a voltage signal from the Josephson junction that can be observed both in the trivial and in the topological phase. Quite remarkably, these voltage signatures are sufficiently different in the two phases such that they can serve as means to clearly distinguish between trivial Andreev and topological Majorana bound states in the system. Moreover, these voltage signatures, in the trivial and topological phase, would allow one to measure directly the quasiparticle poisoning rates and to test various approaches for protection against quasiparticle poisoning.