Weak measurement protocols for Majorana bound state identification

TL;DR

This paper introduces a weak measurement protocol using shot noise correlations to identify Majorana bound states in topological superconductors, offering a less complex alternative to braiding experiments.

Contribution

It presents a novel continuous weak measurement method based on shot noise to distinguish true Majorana states from trivial ones in a practical setup.

Findings

True Majoranas cause distinctive high or low noise levels.

The protocol provides a simpler alternative to braiding for Majorana detection.

The method is adaptable to various experimental platforms.

Abstract

We propose a continuous weak measurement protocol testing the nonlocality of Majorana bound states through current shot noise correlations. The experimental setup contains a topological superconductor island with three normal-conducting leads weakly coupled to different Majorana states. Putting one lead at finite voltage and measuring the shot noise correlations between the other two (grounded) leads, devices with true Majorana states are distinguished from those without by strong current correlations. The presence of true Majoranas manifests itself in unusually high noise levels or the near absence of noise, depending on the chosen device configuration. Monitoring the noise statistics amounts to a weak continuous measurement of the Majorana qubit and yields information similar to that of a full braiding protocol, but at much lower experimental effort. Our theory can be adapted to different platforms and should allow for clear identification of Majorana states.