New stuff with self-organisation

Simon Hertlein

ETH Zurich, Quantum Optics Group -

We report on the experimental realization of a superradiant phase transition of a Bose-Einstein Condensate in a high finesse Cavity with a repulsive pump-lattice, in which the destructive interference between pump and cavity fields lowers the total energy of the system. Due to lattice symmetries, the band structure plays a key role in this process, and we show that the atoms self-organize in the second band with observable consequences for the phase diagram and the atomic momentum distributions.

In this repulsive pump regime, the addition of a running wave transverse pump gives rise to a second type of self-organization phase. We map out the rich phase diagram of the system and identify the phase transition between the two Phases as a first-order transition.

In our latest experiments we utilize this dissipation channel to couple the two phases and create a dynamic instability. The non-stationary dynamics of the self-organized density patterns triggers a novel pumping mechanism.