SciPost Physics (Nov 2020)

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

  • C. W. J. Beenakker, D. O. Oriekhov

DOI
https://doi.org/10.21468/SciPostPhys.9.5.080
Journal volume & issue
Vol. 9, no. 5
p. 080

Abstract

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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.