Phase-coherent thermoelectricity and non-equilibrium Josephson current in Andreev interferometers

TL;DR

This paper presents a comprehensive theory of how non-equilibrium effects and quantum coherence influence thermoelectric and Josephson phenomena in superconducting nanostructures, revealing enhanced signals and new states driven by temperature gradients.

Contribution

It introduces a detailed theoretical framework linking thermoelectric and Josephson effects in superconducting hybrid nanostructures under non-equilibrium conditions.

Findings

Phase-coherent thermoelectric signals are enhanced at temperatures above the Thouless energy.

Non-equilibrium low energy quasiparticles enable strong supercurrents without phase relaxation.

Temperature gradients can induce a $\pi$-junction state, opening new application possibilities.

Abstract

We develop a detailed theory describing a non-trivial interplay between non-equilibrium effects and long-range quantum coherence in superconducting hybrid nanostructures exposed to a temperature gradient. We establish a direct relation between thermoelectric and Josephson effects in such structures and demonstrate that at temperatures exceeding the Thouless energy of our device both phase-coherent thermoelectric signal and the supercurrent may be strongly enhanced due to non-equilibrium low energy quasiparticles propagating across the system without any significant phase relaxation. By applying a temperature gradient one can drive the system into a well pronounced $\pi$-junction state, thereby creating novel opportunities for applications of Andreev interferometers.