Berlin 2014 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 32: Poster: Quantum gases, ultracold atoms and molecules

Q 32.33: Poster

Mittwoch, 19. März 2014, 16:30–18:30, Spree-Palais

Hamiltonian quantum rocking ratchets with ultracold rubidium atoms in an 1D optical lattice — •Christopher Grossert¹, Martin Leder¹, Martin Weitz¹, Sergey Denisov², and Peter Hänggi² — ¹Institute of Applied Physics, University of Bonn, Germany — ²Physics Institute, University of Augsburg, Germany

In periodically driven systems a breaking of spatiotemporal symmetry can lead to directed motion in the absence any gradients or net forces. A biharmonic driving is sufficient to break the relevant symmetries in the classical case [1] as well as in the quantum case [2]. For a dissipative system, this so called rocking ratchet system has been studied in previous work [3]. We here report on the experimental realization of a Hamiltonian quantum rocking ratchet with ultracold ⁸⁷Rb atoms in a 1D optical lattice with biharmonic frequency driving. Other than in previous work of our group [4], the Hamiltonian rocking ratchet transport operates with sinusoidally shaped standing wave optical lattices. In the rocking ratchet system, we observe unique features of a quantum ratchet resonance in control parameter space and bifurcation of quantum resonances as well as a dependence of the atom transport on the initial time of the modulation.

[1] S. Flach et al., Phys. Rev. Lett. 84, 2358 (2000)

[2] Denisov et al., Phys. Rev. A 75, 063424 (2007)

[3] Schiavoni et al., Phys. Rev. Lett. 90, 094101 (2003)

[4] Salger et al., Science 326, 1241 (2009)