A compact design for the Josephson mixer: the lumped element circuit

TL;DR

This paper introduces a compact, efficient Josephson mixer circuit with high gain, broad bandwidth, and good quantum efficiency, suitable for microwave frequency applications.

Contribution

The paper presents a novel lumped-element Josephson mixer design that improves gain, bandwidth, and dynamical range over previous implementations.

Findings

Achieves 20 dB gain over 50 MHz bandwidth

Quantum efficiency of approximately 70%

Saturation power of -112 dBm

Abstract

We present a compact and efficient design in terms of gain, bandwidth and dynamical range for the Josephson mixer, the superconducting circuit performing three-wave mixing at microwave frequencies. In an all lumped-element based circuit with galvanically coupled ports, we demonstrate non degenerate amplification for microwave signals over a bandwidth up to 50 MHz for a power gain of 20 dB. The quantum efficiency of the mixer is shown to be about 70$\%$ and its saturation power reaches $-112$ dBm.