Noise effects in the nonlinear thermoelectricity of a Josephson junction

TL;DR

This paper studies how noise influences the nonlinear thermoelectric effect in a superconducting Josephson junction, revealing that moderate noise can aid detection while excessive noise causes switching, with implications for quantum thermal management.

Contribution

It provides a theoretical analysis of noise effects on thermoelectric phenomena in superconducting junctions, highlighting robustness and noise mitigation strategies.

Findings

Moderate noise enhances thermoelectric signal detection.

Large noise induces switching between thermoelectric states.

Increasing junction capacitance reduces thermoelectric fluctuations.

Abstract

We investigate the noise current in a thermally biased tunnel junction between two superconductors with different zero-temperature gaps. When the Josephson effect is suppressed, this structure can support a nonlinear thermoelectric effect due to the spontaneous breaking of electron-hole symmetry, as we recently theoretically predicted. We discuss the possibly relevant role played by the noise in the junction. While a moderate noise contribution assists the generation of the thermoelectric signal, further unveiling the spontaneous nature of the electron-hole symmetry breaking, a large noise contribution can induce a switching between the two stationary thermoelectric values, thus hardening the detection of the effect and its application. We demonstrate that the thermoelectric effect is robust to the presence of noise for a wide range of parameters and that the spurious fluctuations of the thermoelectric signal can be lowered by increasing the capacitance of the junction, for instance by expanding the junction's size. Our results pave the way to the future experimental observation of the thermoelectric effect in superconducting junctions, and to improved performance in quantum circuits designed for thermal management.