Opto-mecahnics of cold atoms and Bose-Einstein condensates.

We consider theoretically and experimentally the behaviour of cold or ultra-cold atoms interacting with a laser beam in an optical cavity or in a single-feedback mirror set-up. The optical nonlinearity is augmented by the presence of the dipole force where atoms tend to move towards minima or maxima of the light intensity depending on the the difference between their resonant frequency and the frequency of the laser light (opto-mechanics). We observe novel Turing patterns entirely due to opto-mechanic effects in a cloud of cold Rubidium atoms under the action of an input laser beam and a feedback mirror. The role of the (cold) temperature is essential in these experimental realisations. When considering ultra-cold atomic gases (Bose-Einstein condensates) new quantum features appear in the form of a threshold for pattern formation in the atomic density driven by the Heisenberg indetermination principle.

We generalise these spatial features to the case of cold atoms in a cavity where dissipative solitons appear in the atomic density as well as in the light intensity distribution. We also show that conservative chaos occurs in spite of the presence of the external driving and energy dissipation from the cavity mirrors.