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A: Fachverband Atomphysik

A 28: Transport in ultracold gases and plasmas (jointly with Q)

A 28.1: Invited Talk

Friday, March 14, 2008, 11:00–11:30, 3C

Nonlinear coherent transport of waves in disordered media — •Thomas Wellens¹ and Benoît Grémaud² — ¹Physikalisches Institut, Universität Freiburg, Hermann-Herder-Str. 3a, 79104 Freiburg — ²Laboratoire Kastler Brossel, Université Pierre et Marie Curie, 4 place Jussieu, 75252 Paris Cedex 05

In general, transport of waves in disordered media cannot fully be described as a simple diffusion process, since wave interference effects lead to a reduction or even complete suppression of the diffusion constant (weak or strong localization) and the appearance of a coherent backscattering peak.

In this talk, I present a diagrammatic theory for treating the impact of nonlinearities on such disorder-induced localization phenomena [1]. The theory is applied to describe propagation of weakly interacting Bose-Einstein condensates in disordered potentials, on the one hand, and multiple scattering of light in nonlinear media, on the other one. In particular, the conditions under which nonlinear effects diminish or enhance the height of the coherent backscattering peak, and the consequences for the occurrence of Anderson localization of light and cold matter are discussed. Finally, I also talk about the possibility to incorporate quantum-mechanical many-body effects (for example multi-photon scattering processes from strongly driven two-level atoms), which generally lead to decoherence, thereby reducing the localization effects.

[1] T. Wellens and B. Grémaud, PRL (in press)