A macroscopic mechanical resonator driven by mesoscopic electrical back-action.

Systems with coupled mechanical and optical or electrical degrees of freedom have fascinating dynamics that, through macroscopic manifestations of quantum behaviour, provide new insights into the transition between the classical and quantum worlds. Of particular interest is the back-action of electrons and photons on mechanical oscillators, which can lead to cooling and amplification of mechanical motion. Furthermore, feedback, which is naturally associated with back-action, has been predicted to have significant consequences for the noise of a detector coupled to a mechanical oscillator.