Influence of noise on Josephson junctions dynamics with a BCS theory-based model

TL;DR

This paper presents a BCS theory-based simulation tool for Josephson junctions that accurately models their electrodynamics under thermal noise, matching experimental data and revealing noise effects on device performance.

Contribution

The authors developed a novel time-domain simulation model based on BCS theory that accounts for quasiparticles and thermal noise in Josephson junctions, enabling detailed analysis of their behavior.

Findings

Good agreement between simulated and experimental IV curves.

Thermal noise increases the grey zone width of SFQ comparators by 4-20%.

Model works across various waveforms and temperatures below critical.

Abstract

We developed a weak-linked Josephson junction time-domain simulation tool based on the Bardeen-Cooper-Schrieffer (BCS) theory to account for the electrodynamics of Cooper pairs and quasiparticles in the presence of thermal noise. The model, based on Werthamer and Harris formalisms, allows us to describe the behavior of Josephson junctions for various current and/or voltage input waveforms, analog or digital, and for any operating temperature below the critical temperature of the superconducting materials. We show a good agreement between experimental and simulated IV curves of Josephson junctions, as well as a relative increase of the grey zone width of an SFQ balanced comparator between 4 and 20% due to the presence of quasiparticles, for McCumber parameters comprised between 0.1 and 1, respectively.