Conclusions and Outlook

Abstract

In this work we have shown how light can be used to modify the dynamics of a mechanical oscillator via the radiation-pressure force. By utilizing the toolbox of quantum optics, the interaction can in principle be used to demonstrate mechanical quantum behavior of a truly macroscopic system. We have demonstrated the necessary experimental requirements for entering this regime, including a high-finesse Fabry-Pérot cavity, a mechanical resonator with high optical reflectivity and very good mechanical quality, homodyne detection, cryogenic precooling of the mechanical system, a classical-noise free laser system and stable locking loops, among others. In our experiments we have demonstrated all the ingredients needed for showing macroscopic quantum phenomena. We have passively cooled the mechanical motion close to its quantum ground state in a cryogenic cavity, as well as shown that the optical and mechanical system in our experiment can be strongly coupled, which is necessary for achieving coherent energy exchange between the two. In addition, we have performed an experiment where we have measured the correlations of the optical and the mechanical system, a prerequisite for demonstrating optomechanical entanglement. While we did not succeed in actually showing any quantum effect, we are confident that this is within very close reach.