“Tailoring the Dynamics of a Nanomechanical Resonator with (Anti-)squashed Light”
We have designed and implemented a phase–sensitive closed–loop control scheme to engineer the fluctuations of the pump field which drives an optomechanical system. The feedback loop acts on the driving field and it can be engineered to modify the effect of radiation pressure on the mechanical resonator. We first show that, operating in the counter-intuitive “anti-squashing” regime of positive feedback and increased field fluctuations, sideband cooling of a nanomechanical membrane within an optical cavity is improved by 7.5 dB with respect to the case without feedback. Conversely, close to the quantum regime of reduced thermal noise, the scheme would allow using squashed light to go well below the quantum backaction cooling limit, by a margin even larger than that achievable by injecting squeezed light. A further application of anti-squashed light is that it enables a weakly coupled optomechanical system to display normal-mode splitting, which is a typical signature of strongly-coupled systems. In fact, in that case the resonator interacts with an effective very narrow cavity mode modified by feedback.
Host: Jack Harris