To close or not to close: the fate of the superconducting gap across the topological quantum phase transition in Majorana-carrying semiconductor nanowires

摘要

We investigate theoretically the low energy physics of semiconductor Majoranawires in the vicinity of a magnetic field-driven topological quantum phasetransition (TQPT). The local density of states (LDOS) at the end of the wire,which is directly related to the differential conductance in the limit ofpoint-contact tunneling, is calculated numerically. We find that the dependenceof the end-of-wire LDOS on the magnetic field is non-universal and that thesignatures associated with the closing of the superconducting gap at theMajorana TQPT are essentially invisible within a significant range ofexperimentally relevant parameters. Our results provide an explanation for therecent observation of the apparent non-closure of the gap at the Majorana TQPTin semiconductor nanowires.