Fingerprints of Majorana Bound States in Aharonov-Bohm Geometry

Abstract

We study a ring geometry, coupled to two normal metallic leads, which has a Majorana Bound State (MBS) embedded in one of its arms and is threaded by Aharonov-Bohm (AB) flux φ. We show that by varying the AB flux, the two leads go through resonance in an anticorrelated fashion while the resonance conductance is quantized to 2e²/h. We further show that such anticorrelation is completely absent when the MBS is replaced by an Andreev Bound State (ABS). Hence this anti-correlation in conductance when studied as a function of φ provides a unique signature of the MBS which cannot be faked by an ABS. We contrast the phase sensitivity of the MBS and ABS in terms of tunneling conductances. We argue that the relative phase between the tunneling amplitude of the electrons and holes from either lead to the level (MBS or ABS), which is constrained to 0,π for the MBS and unconstrained for the ABS, is responsible for this interesting contrast in the AB effect between the MBS and ABS.