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Q: Quantenoptik
Q 513: Quanteneffekte IV
Q 513.1: Talk
Friday, March 8, 2002, 14:00–14:15, HS 11/215
Dynamical tunnelling of ultracold atoms — •H. Häffner2,3, W.K. Hensinger1,2, A. Browaeys2, N.R. Heckenberg1, K. Helmerson2, C. McKenzie2, G.J. Milburn4, W.D. Phillips2, S.L. Rolston2, H. Rubinsztein-Dunlop1, and B. Upcroft1,2 — 1Centre for Laser Science, Department of Physics, The University of Queensland, Brisbane, Queensland 4072, Australia — 2National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA — 3Institut für Experimental Physik, 6020 Innsbruck, Austria — 4Centre for Quantum Computer Technology, The University of Queensland, Brisbane, Queensland 4072, Australia
We observe tunnelling of ultracold atoms in an amplitude-modulated optical lattice between two distinct sets of motional states. In contrast to the well known energy barrier tunnelling, here the transition between the two sets is forbidden classically by another constant of motion than energy. This new process, “dynamical” tunnelling, was predicted in 1980. It occurs, for example, in periodically driven, nonlinear hamiltonian systems with one degree of freedom. Classically such systems may be chaotic, consisting of regions in phase space of stable, regular motion embedded in a sea of chaos. In our experiment atoms coherently tunnel back and forth between their initial state of oscillatory motion (corresponding to an island of regular motion) and the state oscillating with the opposite phase (corresponding to another island of regular motion).