"Observation of Chaos Assisted Tunneling of Ultra-Cold Atoms"

We study quantum dynamics of ultra-cold cesium atoms in mixed phase space

consisting of islands of stability surrounded by chaos. We use a new

method to prepare a minimum uncertainty wavepacket located on one island in phase space. We observe coherent tunneling oscillations between this state and a symmetry related island. We show that this system exhibits chaos assisted tunneling as characterized by the participation of the intermediate stochastic sea, the sensitivity to

parameters, and the enormous enhancement in the tunneling rate between distant states.