Squeezing Limit of the Josephson Ring Modulator as a Nondegenerate Parametric Amplifier

Two-mode squeezed vacuum states are a crucial component of quantum technologies. In the microwave domain, they can be produced by the Josephson ring modulator that acts as a three-wave mixing nondegenerate parametric amplifier. Here, we numerically solve the full master equation of three bosonic modes describing the Josephson ring modulator 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 nondegenerate parametric amplifier will have an intrinsic squeezing limit in the output fields.

Automated summary

Two-mode squeezed vacuum states are important for quantum technologies and can be generated by a Josephson ring modulator acting as a three-wave mixing nondegenerate parametric amplifier in the microwave domain. By numerically solving the full master equation of the Josephson ring modulator, we calculate squeezing of output fields and gain at low signal power. The results reveal that the third-order interaction from the three-wave mixing process inherently limits squeezing and reduces gain, suggesting an intrinsic squeezing limit in the output fields of any nondegenerate parametric amplifier.