Optomechanical coupling in high-finesse cavities: towards the observation of quantum effects

In quantum mechanics, every measurement induces a back-action on the measured system which usually implies a limit in the sensitivity of the measurement. Our goal is to demonstrate such quantum effects, with an experimental setup based on a high-finesse optical cavity to detect very small displacements of the mirrors. We recently observed a cancellation of the back-action induced by the radiation pressure exerted on the mirrors. Such a cancellation effect may greatly enhance the sensitivity of gravitational-waves detection by dual resonators.