Measuring non-Gaussian fluctuations through incoherent Cooper pair current

TL;DR

This paper demonstrates how a Josephson junction in the incoherent Cooper pair tunneling regime can be used as a wide-band detector for non-Gaussian noise, revealing higher-order noise cumulants.

Contribution

It introduces a method to measure non-Gaussian noise characteristics using a Josephson junction sensitive to excess voltage fluctuations.

Findings

The I-V characteristics are sensitive to the second and third noise cumulants.

Calibration allows extraction of Fano factors and noise frequency dependence.

The approach enables detection of non-Gaussian noise in a broad frequency range.

Abstract

We study a Josephson junction (JJ) in the regime of incoherent Cooper pair tunneling, capacitively coupled to a nonequilibrium noise source. The current-voltage (I-V) characteristics of the JJ are sensitive to the excess voltage fluctuations in the source, and can thus be used for wide-band noise detection. Under weak driving, the odd part of the I-V can be related to the second cumulant of noise, whereas the even part is due to the third cumulant. After calibration, one can measure the Fano factors for the noise source, and get information about the frequency dependence of the noise.