Dresden 2011 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 37: Quantum Chaos II

DY 37.1: Vortrag

Donnerstag, 17. März 2011, 16:00–16:15, ZEU 118

Efficiency of quantum ratchets — •Fei Zhan, Sergey Denisov, Alexey V. Ponomarev, and Peter Hänggi — Insitute of Physics, University of Augsburg, Germany

Directed transport of matter-waves in optical periodic potentials can be initiated by modulation of the potential height, provided that the modulation protocol violates all relevant time and space symmetries. Quantum ratchets [1, 2] might be considered as a potentially new tool for the delivery of cold atoms to a desirable location. Unfortunately, the quantum transport is severely hampered by the diffusive spreading, which is enhanced by tunneling. The optimal regime is the one that maximizes net velocity and minimizes dispersion of the wave packet. We explore the impact of diffusion on the nonequlibrium quantum transport, focusing on the initially localized wave packets. By using a quantum version of the Péclet number, i.e. the ratio between the group velocity and the ballistic dispersion of a propagating matter-wave, we obtain the recipe for the optimization of quantum ratchet performance.

[1] S. Denisov, L. Morales-Molina, S. Flach, and P. Hänggi, Phys. Rev. A 75, 063424 (2007)

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

[3] L. Machura et al., J. Phys. - Condensed Matter 17, S3741 (2005)