Because of their small decay rates, nanomechanical modes enable studying strongly nonlinear phenomena fora moderately strong resonant driving. Here we study the response of a driven resonator to an additional probefield. We experimentally demonstrate resonant amplification and resonant absorption of the probe field. Thecorresponding 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 thesqueezing of fluctuations about the stable states of forced oscillations. Our two-tone experiment is done inthe classical regime, but our findings should equally apply to quantum fluctuations as well. In quantum terms, theobserved response is due to multiphoton processes. The squeezing parameter extracted from the spectra of theresponse is in excellent agreement with the calculated value with no free parameters.     «

Because of their small decay rates, nanomechanical modes enable studying strongly nonlinear phenomena fora moderately strong resonant driving. Here we study the response of a driven resonator to an additional probefield. We experimentally demonstrate resonant amplification and resonant absorption of the probe field. Thecorresponding 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...     »