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Q: Quantenoptik und Photonik

Q 17: Teilchenoptik

Q 17.1: Vortrag

Dienstag, 23. März 2004, 11:00–11:15, HS 224

Interacting atoms in shallow optical lattices — •Andrey R. Kolovsky^1,2 and Andreas Buchleitner¹ — ¹Max-Planck-Institut für Physik komplexer Systeme, D-01187 Dresden — ²Kirensky Institute of Physics, Ru-660036 Krasnoyarsk

We study the spectral and dynamical properties of cold spinless atoms in optical lattices using the Bose-Hubbard formalism, i.e. beyond the mean field approximation. In the case of relatively shallow lattices, where the interaction energy is of the same order as the atomic kinetic energy, the energy spectrum of the system is found to obey Wigner-Dyson statistics (for the Gaussian orthogonal ensemble) and, hence, it can be considered as a quantum chaotic system. This property of ‘chaoticity’ is shown to have a number of important physical consequences. In particular, we consider the response of the system to a static force. Neglecting the atom-atom interaction, this response would be periodic Bloch oscillations of the mean atomic momentum. The atom-atom interaction profoundly modifies these oscillations, which are now quasiperiodic in the case of a strong static force, and decay irreversably, for a weak static force. These two different dynamical regimes are shown to be a manifestation of an ‘order-to-chaos’ transition in the system, with the magnitude of the static force as the control parameter.