Non-degenerate, three-wave mixing with the Josephson ring modulator

TL;DR

This paper analyzes the Josephson ring modulator's ability to perform quantum-limited microwave mixing and amplification, discusses fundamental performance limits, and explores its integration into circuits for quantum applications.

Contribution

It provides a detailed quantum analysis of the JRM, introduces the Josephson parametric converter circuits, and compares experimental results with theoretical predictions.

Findings

JRM can achieve quantum-limited noise performance.

Theoretical and experimental dynamic range are in good agreement.

Fundamental limits on gain, bandwidth, and dynamic range are discussed.

Abstract

The Josephson ring modulator (JRM) is a device, based on Josephson tunnel junctions, capable of performing non-degenerate mixing in the microwave regime without losses. The generic scattering matrix of the device is calculated by solving coupled quantum Langevin equations. Its form shows that the device can achieve quantum-limited noise performance both as an amplifier and a mixer. Fundamental limitations on simultaneous optimization of performance metrics like gain, bandwidth and dynamic range (including the effect of pump depletion) are discussed. We also present three possible integrations of the JRM as the active medium in a different electromagnetic environment. The resulting circuits, named Josephson parametric converters (JPC), are discussed in detail, and experimental data on their dynamic range are found to be in good agreement with theoretical predictions. We also discuss future prospects and requisite optimization of JPC as a preamplifier for qubit readout applications.