Current Correlations in a Majorana Beam Splitter

TL;DR

This paper demonstrates that a Majorana zero mode in a topological superconductor junction causes a universal negative current cross correlation that diminishes as -1/V with increasing bias, unaffected by disorder or temperature.

Contribution

It reveals a universal signature of Majorana zero modes in current correlations, distinguishing them from trivial Andreev bound states.

Findings

Cross correlation is negative and approaches zero as -1/V at high bias.

Universal behavior persists despite disorder and multiple channels.

Accidental Andreev states lead to nonuniversal correlations.

Abstract

We study current correlations in a $T$-junction composed of a grounded topological superconductor and of two normal-metal leads which are biased at a voltage $V$. We show that the existence of an isolated Majorana zero mode in the junction dictates a universal behavior for the cross correlation of the currents through the two normal-metal leads of the junction. The cross correlation is negative and approaches zero at high bias voltages as -1/$V$. This behavior is robust in the presence of disorder and multiple transverse channels, and persists at finite temperatures. In contrast, an accidental low-energy Andreev bound state gives rise to nonuniversal behavior of the cross correlation. We employ numerical transport simulations to corroborate our conclusions.