Axion topological field theory of topological superconductors

TL;DR

This paper develops a topological field theory for three-dimensional time-reversal invariant topological superconductors, revealing novel axion-like couplings and predicting level crossings induced by chiral vortex lines.

Contribution

It introduces a topological field theory description using axion-like couplings for 3D topological superconductors, linking electromagnetic and phase fluctuations.

Findings

Predicts level crossing induced by chiral vortex lines.

Establishes a topological coupling between electromagnetic field and superconducting phase.

Generalizes to include gravitational field coupling.

Abstract

Topological superconductors are gapped superconductors with gapless and topologically robust quasiparticles propagating on the boundary. In this paper, we present a topological field theory description of three-dimensional time-reversal invariant topological superconductors. In our theory the topological superconductor is characterized by a topological coupling between the electromagnetic field and the superconducting phase fluctuation, which has the same form as the coupling of "axions" with an Abelian gauge field. As a physical consequence of our theory, we predict the level crossing induced by the crossing of special "chiral" vortex lines, which can be realized by considering s-wave superconductors in proximity with the topological superconductor. Our theory can also be generalized to the coupling with a gravitational field.