Circular dichroism of chiral Majoranas

Abstract

Majorana states in condensed matter devices may be of a localized nature, such as in hybrid semiconductor/superconductor nanowires, or chirally propagating along the edges such as in hybrid 2D quantum-anomalous-Hall/superconductor structures. We calculate the circular dichroism due to chiral Majorana states in a hybrid structure made of a quantum-anomalous-Hall-insulator and a superconductor. The optical absorption of chiral Majoranas is characterized by equally spaced absorption peaks of both positive and negative dichroism. In the limit of a very long structure (a 2D ribbon) peaks of a single sign are favored. Circular-dichroism spectroscopy of chiral Majoranas is suggested as a relevant probe for these peculiar states of topological matter.