Düsseldorf 2007 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 17: Quantengase (Bosonische Gitter I)
Q 17.2: Vortrag
Dienstag, 20. März 2007, 10:45–11:00, 6J
Phase-dependent Landau-Zener effect in asymmetric optical lattices — •Tobias Salger1,2, Gunnar Ritt1,2, Carsten Geckeler1,2, Sebastian Kling1,2, and Martin Weitz1,2 — 1Institut für Angewandte Physik der Universität Bonn, Wegelerstr. 8, 53115 Bonn, Germany — 2Physikalisches Institut der Universität Tübingen, Auf der Morgenstelle 14, 72076 Tübingen, Germany
We report experimental results on transport properties of Bose-Einstein condensates in periodic optical potentials of variable asymmetry. By studying the Landau-Zener effect and Bloch oscillations, we have explored the band structure of both ratchet-type asymmetric and symmetric optical potentials. In earlier work, quantum transport in “conventional” sinusoidal lattices has proven to be a powerful technique for characterisation of the band structure. To realize lattice potentials of variable asymmetry, we superimpose the conventional lattice potential of λ/2 spatial periodicity with a fourth-order optical potential of λ/4 spatial periodicity. The high periodicity lattice is realized using dispersive properties of multiphoton Raman transitions1. To study quantum transport in such Fourier-synthesized lattice potentials the periodic potential is accelerated. We find that the Landau-Zener tunneling rate between the first and the second excited Bloch band critically depends on the relative phase between the two spatial lattice harmonics. Our experimental results are in agreement with theoretical calculations.
1G. Ritt et al., PRA (in press).
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