Interference of Majorana fermions in NS junctions

TL;DR

This paper derives a formula for charge conductance in NS junctions with Majorana fermions, revealing how interference effects lead to a range of conductance values depending on system symmetry, including complete destructive interference.

Contribution

It provides a general conductance formula for NS junctions with two Majorana fermions and analyzes the symmetry conditions causing destructive interference.

Findings

Conductance varies from 0 to 4e^2/h due to Majorana interference.

Quantized conductance of 2e^2/h for a single Majorana fermion.

Symmetry determines the interference pattern and conductance values.

Abstract

We investigate interference of Majorana fermions (MFs) in NS junctions. A general formula of charge conductance G for NS junctions with two MFs is derived based on the low energy effective model. It is found that G for two MFs takes various values 0 \leq G \leq 4e^2/h owing to interference of the MFs, while G is quantized as G = 2e^2/h for a single MF. The value of G is determined by symmetry of the system. As an example, we investigate the complete destructive interference of two degenerate MFs reported by Ii et al. [A. Ii, A. Yamakage, K. Yada, M. Sato, and Y. Tanaka, Phys. Rev. B 86, 174512 (2012)], and identify the symmetry responsible for the destructive interference.