Mechanical squeezing via parametric amplification and weak measurement

TL;DR

This paper demonstrates that by applying continuous weak measurement and feedback to a mechanically parametric amplifier, unlimited steady-state squeezing below the zero-point motion can be achieved, relaxing previous limitations.

Contribution

The study introduces a method to achieve unlimited steady-state mechanical squeezing using optimal detuning, weak measurement, and feedback, surpassing traditional 3dB limits.

Findings

Unlimited steady-state squeezing achieved with optimal detuning.

Relaxed measurement strength, temperature, and efficiency requirements.

Correlations between quadratures enable enhanced squeezing.

Abstract

Nonlinear forces allow motion of a mechanical oscillator to be squeezed below the zero-point motion. Of existing methods, mechanical parametric amplification is relatively accessible, but previously thought to be limited to 3dB of squeezing in the steady state. We consider the effect of applying continuous weak measurement and feedback to this system. If the parametric drive is optimally detuned from resonance, correlations between the quadratures of motion allow unlimited steady-state squeezing. Compared to back-action evasion, we demonstrate that the measurement strength, temperature and efficiency requirements for quantum squeezing are significantly relaxed.