Optical response of edge modes in time-reversal symmetric topological superconductors

TL;DR

This paper investigates the optical responses of Majorana and Dirac edge modes in topological superconductors, revealing distinct optical signatures that could aid experimental identification of Majorana modes.

Contribution

The study provides a detailed analysis of optical conductivity in topological superconductors, highlighting differences between Majorana and Dirac edge modes under various symmetries.

Findings

Majorana and Dirac edge modes show different optical responses.

Numerical and analytical calculations confirm distinct optical signatures.

Results applicable to ${ m Z}_2$ topological insulators and superconductors.

Abstract

Topological superconductors and Majorana edge modes at their boundaries have been theoretically predicted. However, their experimental observation remains controversial. Recent theoretical studies suggest that chiral Majorana edge modes exhibit distinct spatially-resolved optical conductivity compared to chiral Dirac edge modes. In this work, we investigate the optical conductivity and spatially-resolved optical conductivity induced by Majorana edge modes and Dirac edge modes under time-reversal symmetry and crystalline symmetry. We conduct numerical calculations and analytical calculations with edge effective theory for two-dimensional ${\mathbb Z}_2$ topological insulators, strong topological superconductors, and topological crystalline superconductors. Our results show that even under time-reversal symmetry and crystalline symmetry, Majorana edge modes and Dirac edge modes exhibit different optical responses.