Signatures of Majorana Fermions in Topological Insulator Josephson Junction Devices

TL;DR

This paper theoretically investigates electrical current and noise in a topological insulator Josephson junction with a ring geometry, identifying signatures of Majorana fermions through conductance jumps and non-local correlations at specific phase differences.

Contribution

It introduces a novel ring geometry setup to detect Majorana fermions via conductance and noise signatures in topological insulator Josephson junctions.

Findings

Conductance jumps at phase difference  in the ring.

Non-local current correlations observed near  phase difference.

Dependence of signatures on temperature, voltage, and device dimensions.

Abstract

We study theoretically the electrical current and low-frequency noise for a linear Josephson junction structure on a topological insulator, in which the superconductor forms a closed ring and currents are injected from normal regions inside and outside the ring. We find that this geometry offers a signature for the presence of gapless 1D Majorana fermion modes that are predicted in the channel when the phase difference \phi, controlled by the magnetic flux through the ring, is \pi. We show that for low temperature the linear conductance jumps when \phi\ passes through \pi, accompanied by non-local correlations between the currents from the inside and outside of the ring. We compute the dependence of these features on temperature, voltage and linear dimensions, and discuss the implications for experiments.