Amplification and spectral evidence of squeezing in the response of a strongly driven nanoresonator to a probe field

TL;DR

This paper investigates how a strongly driven nanoresonator responds to a probe field, revealing amplification, absorption, and squeezing of fluctuations, with results applicable to both classical and quantum regimes.

Contribution

It demonstrates resonant amplification and absorption in a driven nanoresonator and links spectral features to fluctuation squeezing, extending understanding to quantum-like multiphoton processes.

Findings

Spectral peaks appear on opposite sides of the drive frequency.

Response characterizes squeezing of fluctuations in the resonator.

Measured squeezing parameter matches theoretical calculations.

Abstract

Because of their small decay rates, nanomechanical modes enable studying strongly nonlinear phenomena for a moderately strong resonant driving. Here we study the response of a driven resonator to an additional probe field. We experimentally demonstrate resonant amplification and resonant absorption of the probe field. The corresponding spectral peaks lie on the opposite sides of the strong-drive frequency. Even though the fluctuation-dissipation theorem does not apply, we show that the response to the probe field allows us to characterize the squeezing of fluctuations about the stable states of forced oscillations. Our two-tone experiment is done in the classical regime, but our findings should equally apply to quantum fluctuations as well. In quantum terms, the observed response is due to multiphoton processes. The squeezing parameter extracted from the spectra of the response is in excellent agreement with the calculated value with no free parameters.