Noise effects in the nonlinear thermoelectricity of a Josephson junction

G. Marchegiani, A. Braggio, F. Giazotto

Published 2020-09-11Version 1

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.