Currents and current correlations in a topological superconducting nanowire beam splitter

TL;DR

This paper investigates a topological superconducting nanowire beam splitter, revealing how Majorana bound states influence current correlations and exhibit unique particle-hole symmetry, with potential for experimental detection.

Contribution

It demonstrates the sign change in current cross-correlations due to Majorana overlap and identifies a distinctive local particle-hole symmetry in the system.

Findings

Current cross-correlations change sign with Majorana overlap.

Net current is noiseless under symmetric bias voltages.

Unique local particle-hole symmetry can be detected via current measurements.

Abstract

A beam splitter consisting of two normal leads coupled to one end of a topological superconducting nanowire via double quantum dot is investigated. In this geometry, the linear current cross-correlations at zero temperature change signs versus the overlap between the two Majorana bound states hosted by the nanowire. Under symmetric bias voltages the net current flowing through the nanowire is noiseless. These two features highlight the fermionic nature of such exotic Majorana excitations though they are based on the superconductivity. Moreover, there exists a unique local particle-hole symmetry inherited from the self-Hermitian property of Majorana bound states, which is apparently scarce in other systems. We show that such particular symmetry can be revealed through measuring the currents under complementary bias voltages.