Conductance spectroscopy of topological superconductor wire junctions

TL;DR

This paper analyzes the conductance properties of topological superconductor junctions, confirming quantized zero-bias conductance in the topological phase and exploring how conductance spectra evolve with system parameters.

Contribution

It provides an analytical study of tunneling conductance in topological superconductor junctions using generalized BTK formalism for two models.

Findings

Zero-bias conductance is quantized at 2e^2/h in the topological phase.

Conductance spectra show a zero-bias peak in the topological state.

Peak width depends on spin-orbit coupling and barrier transparency.

Abstract

We study the zero-temperature transport properties of one-dimensional normal-superconductor (NS) junctions with topological superconductors across their topological transitions. Working within the Blonder-Tinkham-Klapwijk (BTK) formalism generalized for topological NS junctions, we analytically calculate the differential conductance for tunneling into two models of a topological superconductor: a spinless intrinsic $p$-wave superconductor and a spin-orbit-coupled $s$-wave superconductor in a Zeeman field. In both cases we verify that the zero-bias conductance is robustly quantized at $2e^2/h$ in the topological regime, while it takes nonuniversal values in the non-topological phase. The conductance spectra in the topological state develops a peak at zero bias for certain parameter regimes, with the peak width controlled by the strength of spin-orbit coupling and barrier transparency.