Quantum nondemolition measurement of mechanical squeezed state beyond the 3 dB limit

TL;DR

This paper demonstrates a reservoir engineering technique in a microwave optomechanical system that achieves a mechanical squeezed state with 4.7 dB of squeezing below the zero-point level, surpassing the traditional 3 dB limit.

Contribution

The authors introduce a two-tone driving reservoir engineering method that stabilizes and enhances mechanical squeezing beyond the 3 dB limit, including evidence of a mechanical parametric effect.

Findings

Achieved 4.7 dB of squeezing below zero-point level.

Surpassed the 3 dB squeezing limit of standard techniques.

Identified an additional mechanical parametric effect that enhances squeezing.

Abstract

We use a reservoir engineering technique based on two-tone driving to generate and stabilize a quantum squeezed state of a micron-scale mechanical oscillator in a microwave optomechanical system. Using an independent backaction evading measurement to directly quantify the squeezing, we observe $4.7\pm0.9$ dB of squeezing below the zero-point level, surpassing the 3 dB limit of standard parametric squeezing techniques. Our measurements also reveal evidence for an additional mechanical parametric effect. The interplay between this effect and the optomechanical interaction enhances the amount of squeezing obtained in the experiment.