Detection of Majorana Kramers pairs using a quantum point contact

TL;DR

This paper proposes a setup combining a quantum point contact and a Josephson junction on a quantum spin Hall system to detect Majorana Kramers pairs through distinctive transport signatures.

Contribution

It introduces a novel experimental configuration for detecting Majorana Kramers pairs using a QPC and Josephson junction in InAs/GaSb quantum wells.

Findings

Robust switching from normal to Andreev scattering due to Majorana pairs

Detection via differential conductance and current cross-correlation

Applicable to quantum spin Hall systems like InAs/GaSb

Abstract

We propose a setup that integrates a quantum point contact (QPC) and a Josephson junction on a quantum spin Hall sample, experimentally realizable in InAs/GaSb quantum wells. The confinement due to both the QPC and the superconductor results in a Kramers pair of Majorana zero-energy bound states when the superconducting phases in the two arms differ by an odd multiple of $\pi$ across the Josephson junction. We investigate the detection of these Majorana pairs with the integrated QPC, and find a robust switching from normal to Andreev scattering across the edges due to the presence of Majorana Kramers pairs. This transport signature is expected to be exhibited in measurements of differential conductance and/or current cross-correlation at low bias.