Andreev Bound states in One Dimensional Topological Superconductor

TL;DR

This paper investigates the charge properties of Andreev bound states in one-dimensional topological superconductors, revealing hidden symmetries that determine their charge and proposing experimental detection methods.

Contribution

It uncovers a hidden symmetry in the Bogoliubov de Gennes equations that influences ABS charge, and links charge neutrality to the presence of spatial inversion symmetry.

Findings

ABS charge depends on Fermi velocities in the absence of SIS.

ABS are charge neutral when SIS is present.

Tunneling spectroscopy can measure ABS charge.

Abstract

We study the charge character of the Andreev bound states (ABSs) in one-dimensional topological superconductors with spatial inversion symmetry (SIS) breaking. Despite the absence of the SIS, we show a hidden symmetry for the Bogoliubov de Gennes equations around Fermi points in addition to the particle-hole symmetry. This hidden symmetry protects that the charge of the ABSs is solely dependent on the corresponding Fermi velocities. On the other hand, if the SIS is present, the ABSs are charge neutral, similar to Majorana fermions. We demonstrate that the charge of the ABSs can be experimentally measured in the tunneling transport spectroscopy from the resonant differential tunneling conductance.