Three-wave mixing with three incoming waves: Signal-Idler Coherent Cancellation and Gain Enhancement in a Parametric Amplifier

TL;DR

This paper demonstrates a reciprocal three-wave mixing process in a Josephson amplifier, revealing phase-sensitive modulation and gain enhancement through coherent cancellation when signal and idler beams deplete the pump.

Contribution

It introduces the concept of reciprocal three-wave mixing with coherent cancellation in superconducting amplifiers, expanding understanding of phase-sensitive control in quantum circuits.

Findings

Coherent cancellation causes significant gain modulation.

Reciprocal process aligns with theoretical predictions.

Enhanced gain observed with strong signal and idler beams.

Abstract

Coherent, purely-dispersive three-wave mixing systems in optics and superconducting microwave circuits can be operated as parametric amplifiers, generating from a pump wave at one frequency amplified signal and idler waves at lower frequencies. Here we demonstrate the reciprocal process using a Josephson amplifier in which coherently imposed signal and idler beams up-convert to the pump frequency. For signal and idler beams strong enough to significantly deplete the pump, we show that this reciprocal process ("coherent cancellation") leads to large, phase-sensitive modulation and even enhancement of the amplifier gain, in good agreement with theoretical predictions.