Detecting Current Noise with a Josephson Junction in the Macroscopic Quantum Tunneling Regime

TL;DR

This paper proposes using a hysteretic Josephson junction as a sensitive detector for low-frequency current noise, leveraging macroscopic quantum tunneling measurements to analyze noise characteristics, including higher-order cumulants.

Contribution

It introduces a novel experimental scheme for detecting and characterizing low-frequency current noise using a Josephson junction in the macroscopic quantum tunneling regime.

Findings

Demonstrates the feasibility of using switching measurements to detect noise-affected tunneling rates.

Relates the third cumulant of current fluctuations to asymmetries in switching rates.

Proposes an on-chip filtering circuit to limit noise frequency range.

Abstract

We discuss the use of a hysteretic Josephson junction to detect current fluctuations with frequencies below the plasma frequency of the junction. These adiabatic fluctuations are probed by switching measurements observing the noise-affected average rate of macroscopic quantum tunneling of the detector junction out of its zero-voltage state. In a proposed experimental scheme, frequencies of the noise are limited by an on-chip filtering circuit. The third cumulant of current fluctuations at the detector is related to an asymmetry of the switching rates.