Read-Green resonances in a topological superconductor coupled to a bath

TL;DR

This paper investigates how particle exchange with an environment affects a topological superconductor, revealing resonances at Read-Green points that are not captured by mean-field theory, thus highlighting the importance of exact solutions.

Contribution

It introduces an integrable model for a topological superconductor coupled to a bath, showing the persistence of Read-Green resonances beyond mean-field approximations.

Findings

Resonances occur at Read-Green points during particle exchange.

Zero-energy modes influence system-environment particle exchange.

Mean-field theory fails to capture these topologically protected resonances.

Abstract

We study a topological superconductor capable of exchanging particles with an environment. This additional interaction breaks particle-number symmetry and can be modelled by means of an integrable Hamiltonian, building on the class of Richardson-Gaudin pairing models. The isolated system supports zero-energy modes at a topological phase transition, which disappear when allowing for particle exchange with an environment. However, it is shown from the exact solution that these still play an important role in system-environment particle exchange, which can be observed through resonances in low-energy and -momentum level occupations. These fluctuations signal topologically protected Read-Green points and cannot be observed within traditional mean-field theory.