Probing the topological character of superconductors via non-local Hanbury-Brown and Twiss correlations

TL;DR

This paper uses non-local Hanbury-Brown and Twiss correlations and conductance measurements to distinguish topological from non-topological superconductors, aiding in the search for Majorana fermions for quantum computing.

Contribution

It introduces a novel method using HBT shot noise correlations to identify topological superconductors and differentiate them from non-topological ones.

Findings

HBT correlations are asymmetric in non-topological superconductors.

HBT correlations are symmetric in topological superconductors regardless of barrier strength.

The method helps in identifying Majorana fermions for quantum computing.

Abstract

Superconductors can be classified as topological or not based on whether time-reversal symmetry (TRS), chiral symmetry, and particle-hole symmetry are preserved or not. Further, topological superconductors can also be classified as chiral or helical. In this paper, using Hanbury-Brown and Twiss (HBT) shot noise correlations and the non-local conductance, we probe metal/2D unconventional superconductor/metal junctions to understand better the pairing topological vs. non-topological or helical vs. chiral or nodal vs. gapful. We see that HBT correlations are asymmetric as a function of bias voltage for non-topological superconductors, whereas they are symmetric for topological superconductors irrespective of the barrier strength. Topological superconductors are associated with Majorana fermions which are important for topological quantum computation. By distinguishing topological superconductors from non-topological superconductors, our study will help search for Majorana fermions, which will aid in designing a topological quantum computer.