Shot noise distinguishes Majorana fermions from vortices injected in the edge mode of a chiral p-wave superconductor

TL;DR

This paper demonstrates that shot noise measurements can distinguish between Majorana fermions and edge vortices in a chiral p-wave superconductor, revealing unique nonlocal noise behavior associated with vortices.

Contribution

It introduces a method to differentiate Majorana fermions from edge vortices using shot noise analysis, highlighting the nonlocality and V log V behavior of vortex-induced noise.

Findings

Shot noise increases logarithmically with vortex spacing.

Vortex shot noise exhibits a V log V dependence in voltage-biased setups.

Majorana fermion shot noise remains linear in voltage, contrasting with vortices.

Abstract

The chiral edge modes of a topological superconductor support two types of excitations: fermionic quasiparticles known as Majorana fermions and $\pi$-phase domain walls known as edge vortices. Edge vortices are injected pairwise into counter-propagating edge modes by a flux bias or voltage bias applied to a Josephson junction. An unpaired edge mode carries zero electrical current on average, but there are time-dependent current fluctuations. We calculate the shot noise power produced by a sequence of edge vortices and find that it increases logarithmically with their spacing - even if the spacing is much larger than the core size so the vortices do not overlap. This nonlocality produces an anomalous V log V increase of the shot noise in a voltage-biased geometry, which serves as a distinguishing feature in comparison with the linear-in-V Majorana fermion shot noise.