Atomic control of quantum optomechanical systems

Recent experiments have shown how a genuine quantum behavior can be observed at a mesoscopic scale.
Particularly noteworthy in such a quest are quantum optomechanical systems and trapped ultracold gases.
Interestinly enough it has been shown how the dynamics of a trapped BEC dispersively coupled with a cavity
field can be described itself in term of an effective optomechanical coupling.
In this talk we will describe how the dynamics of a quantum optomechanical system can be controlled by
a trapped BEC or by a single atom dispersively coupled with the cavity field. Such schemes are shown to be a
paradigmatic example of how the quantum dynamic of a mesoscopic quantum system can be controlled by
another mesoscopic or even microscopic quantum system.