Phase preserving amplification near the quantum limit with a Josephson Ring Modulator

TL;DR

This paper reports the first phase-preserving, non-degenerate superconducting amplifier using a Josephson ring modulator, achieving near-quantum-limited noise performance for quantum information processing.

Contribution

Introduction of a novel Josephson ring modulator-based amplifier that is phase-preserving, non-degenerate, and operates close to the quantum noise limit.

Findings

Achieved gain and bandwidth consistent with theoretical predictions.

Operates within a factor of three of the quantum limit.

Device symmetry enhances amplification purity and simplifies operation.

Abstract

Recent progress in solid state quantum information processing has stimulated the search for ultra-low-noise amplifiers and frequency converters in the microwave frequency range, which could attain the ultimate limit imposed by quantum mechanics. In this article, we report the first realization of an intrinsically phase-preserving, non-degenerate superconducting parametric amplifier, a so far missing component. It is based on the Josephson ring modulator, which consists of four junctions in a Wheatstone bridge configuration. The device symmetry greatly enhances the purity of the amplification process and simplifies both its operation and analysis. The measured characteristics of the amplifier in terms of gain and bandwidth are in good agreement with analytical predictions. Using a newly developed noise source, we also show that our device operates within a factor of three of the quantum limit. This development opens new applications in the area of quantum analog signal processing.