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

Abstract

The chiral edge modes of a topological superconductor support two types of excitations: fermionic quasiparticles known as Majorana fermions and \bm\pi𝛑-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 \bm{V\ln V}𝐕ln𝐕 increase of the shot noise in a voltage-biased geometry, which serves as a distinguishing feature in comparison with the linear-in-\bm V𝐕 Majorana fermion shot noise.