Quantized conductance at the Majorana phase transition in a disordered superconducting wire

TL;DR

This paper demonstrates that a topological phase transition in disordered superconducting wires supporting Majorana states can be detected through quantized thermal conductance, shot noise, and magnetoconductance oscillations, regardless of disorder level.

Contribution

It introduces a method to identify the topological phase transition via quantized conductance and noise signatures, independent of disorder effects.

Findings

Quantized thermal conductance signals the phase transition.

Electrical shot noise power also indicates the transition.

Period doubling in magnetoconductance oscillations marks the phase change.

Abstract

Superconducting wires without time-reversal and spin-rotation symmetries can be driven into a topological phase that supports Majorana bound states. Direct detection of these zero-energy states is complicated by the proliferation of low-lying excitations in a disordered multi-mode wire. We show that the phase transition itself is signaled by a quantized thermal conductance and electrical shot noise power, irrespective of the degree of disorder. In a ring geometry, the phase transition is signaled by a period doubling of the magnetoconductance oscillations. These signatures directly follow from the identification of the sign of the determinant of the reflection matrix as a topological quantum number.