# Thermopower and thermal conductance of a superconducting quantum point contact

## TL;DR

This paper develops a comprehensive theory for charge and heat currents in superconducting quantum point contacts, valid across transmission regimes, and clarifies the limits of existing tunneling approaches.

## Contribution

It introduces a new theoretical framework relating currents to the scattering matrix, applicable at any transmission, especially improving understanding in low-transmission scenarios.

## Key findings

- Derived formulas for charge and heat currents based on scattering matrices.
- Validated the theory's reliability in the low-transmission limit.
- Clarified the applicability bounds of the tunnel Hamiltonian method.

## Abstract

We find the charge and heat currents caused by a temperature difference applied to a superconducting point contact or to a quantum point contact between a superconducting and normal conductors. The results are formulated in terms of the properties of the electron scattering matrix of the quantum point contact in its normal state, and are valid at any transmission coefficient. In the low-transmission limit, the new theory provides reliable results, setting the limits for the use of the popular method of tunnel Hamiltonian.