Squeezing Limit of the Josephson Ring Modulator as a Non-Degenerate Parametric Amplifier

TL;DR

This paper analyzes the fundamental squeezing limits of Josephson ring modulators used as non-degenerate parametric amplifiers in quantum microwave technologies, revealing intrinsic constraints due to three-wave mixing interactions.

Contribution

It introduces a novel numerical method to solve the master equation for three bosonic modes, providing new insights into the intrinsic squeezing and gain limits of these amplifiers.

Findings

Third-order interactions intrinsically limit squeezing.

Gain is reduced by the three-wave mixing process.

Limits are applicable to all cavity-based non-degenerate parametric amplifiers.

Abstract

Two-mode squeezed vacuum states are a crucial component of quantum technologies. In the microwave domain, they can be produced by Josephson ring modulator which acts as a three-wave mixing non-degenerate parametric amplifier. Here, we solve the master equation of three bosonic modes describing the Josephson ring modulator with a novel numerical method to compute squeezing of output fields and gain at low signal power. We show that the third-order interaction from the three-wave mixing process intrinsically limits squeezing and reduces gain. Since our results are related to other general cavity-based three-wave mixing processes, these imply that any non-degenerate parametric amplifier will have an intrinsic squeezing limit in the output fields.