On the Electromagnetic Response of Topological Superconductors

TL;DR

This paper clarifies the electromagnetic response of 3+1D topological superconductors, showing that their interfaces do not exhibit quantum Hall effects under time reversal symmetry, contrasting with topological insulators.

Contribution

It analytically demonstrates the absence of quantum Hall effect at topological superconductor interfaces under time reversal invariance, contrasting with topological insulators.

Findings

Interface between topological and normal superconductor shows no quantum Hall effect.

Electromagnetic coupling differs between topological insulators and superconductors due to fermion mass types.

Topological superconductor interfaces preserve time reversal symmetry, affecting electromagnetic response.

Abstract

We resolve several puzzles related to the electromagnetic response of topological superconductors in 3+1 dimensions. In particular we show by an analytical calculation that the interface between a topological and normal superconductor does not exhibit any quantum Hall effect as long as time reversal invariance is preserved. We contrast this with the analogous case of a topological insulator to normal insulator interface. The difference is that in the topological insulator the electromagnetic vector potential couples to a vector current in a theory with a Dirac mass, while in the superconductor a pair of Weyl fermions are gapped by Majorana masses and the electromagnetic vector potential couples to their axial currents.