Measuring the distribution of current fluctuations through a Josephson junction with very short current pulses

TL;DR

This paper introduces a method using short current pulses in Josephson junctions to measure current fluctuation distributions, analyzing the impact of higher cumulants and demonstrating detection in realistic noise scenarios.

Contribution

It presents a novel approach to probe current fluctuation distributions via escape probability histograms with short pulses, including analysis of higher cumulants effects.

Findings

Higher cumulants influence the escape probability derivative.

Detection of skewness in current fluctuations is possible.

Method applicable to realistic noise sources like tunnel junctions and telegraph noise.

Abstract

We propose to probe the distribution of current fluctuations by means of the escape probability histogram of a Josephson junction (JJ), obtained using very short bias current pulses in the adiabatic regime, where the low-frequency component of the current fluctuations plays a crucial role. We analyze the effect of the third cumulant on the histogram in the small skewness limit, and address two concrete examples assuming realistic parameters for the JJ. In the first one we study the effects due to fluctuations produced by a tunnel junction, finding that the signature of higher cumulants can be detected by taking the derivative of the escape probability with respect to current. In such a realistic situation, though, the determination of the whole distribution of current fluctuations requires an amplification of the cumulants. As a second example we consider magnetic flux fluctuations acting on a SQUID produced by a random telegraph source of noise.