Anticorrelation between temperature and fluctuations in moderately damped Josephson junctions

TL;DR

This study investigates how dissipation affects switching current fluctuations in Josephson junctions, revealing a paradoxical decrease in fluctuations with increasing temperature due to thermal fluctuation interplay.

Contribution

It demonstrates the anticorrelation between temperature and fluctuation amplitude in Josephson junctions, highlighting the role of dissipation and thermal effects in switching behavior.

Findings

Switching current fluctuations collapse with increasing temperature.

Dissipation critically influences fluctuation behavior.

Thermal fluctuations both assist and hinder switching.

Abstract

We study the influence of dissipation on the switching current statistics of moderately damped Josephson junctions. Different types of both low- and high- $T_c$ junctions with controlled damping are studied. The damping parameter of the junctions is tuned in a wide range by changing temperature, magnetic field, gate voltage, introducing a ferromagnetic layer or in-situ capacitive shunting. A paradoxical collapse of switching current fluctuations occurs with increasing $T$ in all studied junctions. The phenomenon critically depends on dissipation in the junction and is explained by interplay of two counteracting consequences of thermal fluctuations, which on the one hand assist in premature switching into the resistive state and on the other hand help in retrapping back to the superconducting state. This is one of the rare examples of anticorrelation between temperature and fluctuation amplitude of a physically measurable quantity.