Control of Coulomb blockade in a mesoscopic Josephson junction using single electron tunneling

TL;DR

This paper demonstrates how a mesoscopic Josephson junction's Coulomb blockade can be controlled via a normal metal-superconductor tunnel junction, enabling transistor-like behavior with high current gain and low noise.

Contribution

It introduces a method to control Coulomb blockade in a Josephson junction using a NIS tunnel junction, combining theoretical analysis, simulations, and experimental validation.

Findings

Achieved substantial current gain with low current noise.

Demonstrated noise temperature below 0.1 K.

Found good agreement between simulations and experiments.

Abstract

We study a circuit where a mesoscopic Josephson junction (JJ) is embedded in an environment consisting of a large bias resistor and a normal metal - superconductor tunnel junction (NIS). The effective Coulomb blockade of the JJ can be controlled by the tunneling current through the NIS junction leading to transistor-like characteristics. We show using phase correlation theory and numerical simulations that substantial current gain with low current noise ($i_{n}\lesssim 1$ fA/$\sqrt{\text{Hz}}$) and noise temperature ($\lesssim $ 0.1 K) can be achieved. Good agreement between our numerical simulations and experimental results is obtained.