Diagnosing Topological Phase Transitions in 1D Superconductors using Berry Singularity Markers

TL;DR

This paper demonstrates how Berry singularity markers can be used to identify topological phase transitions in 1D superconductors, specifically in the Kitaev chain model and its variants, with potential experimental applications.

Contribution

It introduces the application of Berry singularity markers to characterize topological phase transitions in 1D superconductors, including practical detection methods.

Findings

Berry singularity markers successfully identify topological charges.

External fields like flux and strain can detect topological phase transitions.

Method is experimentally feasible for topological nanowire systems.

Abstract

In this work I demonstrate how to characterize topological phase transitions in BDI symmetry class superconductors (SCs) in 1D, using the recently introduced approach of Berry singularity markers (BSMs). In particular, I apply the BSM method to the celebrated Kitaev chain model, as well as to a variant of it, which contains both nearest and next nearest neighbor equal spin pairings. Depending on the situation, I identify pairs of external fields which can detect the topological charges of the Berry singularities which are responsible for the various topological phase transitions. These pairs of fields consist of either a flux knob which controls the supercurrent flow through the SC, or, strain, combined with a field which can tune the chemical potential of the system. Employing the present BSM approach appears to be within experimental reach for topological nanowire hybrids.