Stuttgart 2012 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 39: Quantengase: Wechselwirkungseffekte 2

Q 39.3: Vortrag

Donnerstag, 15. März 2012, 11:15–11:30, V7.01

Microscopic Scattering Theory for Interacting Bosons in a Random Potential — •Tobias Geiger, Thomas Wellens, and Andreas Buchleitner — Physikalisches Institut, Universität Freiburg, Hermann-Herder-Str. 3, 79104 Freiburg

We microscopically derive a theory for scattering of N atoms – with all atoms initially prepared in the same single-particle momentum eigenstate – from a three dimensional random disorder potential in the presence of two-body interactions. Starting from an exact diagrammatic expansion of the N-particle scattering amplitude, we identify those combinations of diagrams which – in the case of a weak random potential (mean free path much larger than wavelength) – survive the disorder average, and sum up the remaining ladder and crossed diagrams non-perturbatively in the strength of the particle-particle interaction [1]. We show that the latter leads to a relaxation of the individual particles’ energies towards a Maxwell-Boltzmann distribution as the particles diffuse throughout the random potential. As interferential correction to diffusive transport, we furthermore consider coherent backscattering and analyze how this coherent effect is modified by interactions.

[1] T. Wellens and B. Grémaud, Phys. Rev. Lett. 100, 033902 (2008).