Thermopower of three-terminal topological superconducting systems

TL;DR

This paper investigates the thermopower behavior in a three-terminal quantum dot system with either trivial or topological superconductors, revealing temperature-dependent sign changes linked to the superconductor type.

Contribution

It provides a comparative analysis of thermopower in systems with s-wave and p-wave superconductors, highlighting the influence of topological properties on thermoelectric response.

Findings

Thermopower sign differs between trivial and topological superconductors at low temperatures.

The sign change depends on an energy scale proportional to the square root of the superconducting gap.

Results from a simple 1D model are validated by a more realistic tight-binding model.

Abstract

We study the thermopower of a three-terminal setup composed of a quantum dot attached to three electrodes, one of which is a topological superconductor. In the model, superconductivity is explicitly taken into account. We compare the results for s-wave (trivial) and p-wave (topological) superconductors and observe that for small temperatures the thermopower has different sign in the two cases. This behavior is strongly dependent on temperature and we estimate an energy scale that controls the sign in the p-wave case, which results proportional to the square root of the gap and the coupling to superconductor. The analytical results obtained with a simple 1D model are confirmed by a more realistic tight-binding model.