Düsseldorf 2007 – wissenschaftliches Programm

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A: Fachverband Atomphysik

A 1: Quantengase (jointly with Q)

A 1.6: Vortrag

Montag, 19. März 2007, 11:45–12:00, 6J

Coherent Control of the Superfluid-to-Mott-Insulator Transition — •Andre Eckardt and Martin Holthaus — Institut für Physik, Carl von Ossietzky Universität, 26111 Oldenburg

We demonstrate that the transition from a superfluid to a Mott-insulator in the Bose-Hubbard-Modell can be controlled coherently by an oscillating force through an effective renormalization of the tunneling matrix element [1]. The mechanism involves adiabatic following of Floquet-states in combination with diabatic passing of tiny avoided crossings in the quasienergy spectrum that indicate interaction-induced resonant coupling to excited states. Deviations from this ideal dynamics result in a loss of coherence, i.e., heating of the system. We investigate conditions for a controlled time-evolution with respect to frequency, amplitude and switching time of the drive, and discuss a possible scenario for the limit of large lattices. The estimation of experimentally accessible parameters suggests that both the regime of coherent control and its limits can be observed with ultracold atoms in optical lattices.

[1] A. Eckardt, C. Weiss, and M. Holthaus, Superluid-Insulator Transition in a Periodically Driven Optical Lattice, Phys. Rev. Lett. 95, 260404 (2005)