Issue
EPL
Volume 83, Number 1, July 2008
Article Number 10006
Number of page(s) 6
Section General
DOI http://dx.doi.org/10.1209/0295-5075/83/10006
Published online 18 June 2008
EPL, 83 (2008) 10006
DOI: 10.1209/0295-5075/83/10006

Anisotropic scattering of Bogoliubov excitations

C. Gaul and C. A. Müller

Universität Bayreuth - 95440 Bayreuth, Germany, EU

christopher.gaul@uni-bayreuth.de

received 26 March 2008; accepted in final form 22 May 2008; published July 2008
published online 18 June 2008

Abstract
We consider elementary excitations of an interacting Bose-Einstein condensate in the mean-field framework. As a building block for understanding the dynamics of systems comprising interaction and disorder, we study the scattering of Bogoliubov excitations by a single external impurity potential. A numerical integration of the Gross-Pitaevskii equation shows that the single-scattering amplitude has a marked angular anisotropy. By a saddle point expansion of the hydrodynamic mean-field energy functional, we derive the relevant scattering amplitude including the crossover from sound-like to particle-like excitations. The very different scattering properties of these limiting cases are smoothly connected by an angular envelope function with a well-defined node of vanishing scattering amplitude. We find that the overall scattering is most efficient at the crossover from phonon-like to particle-like Bogoliubov excitations.

PACS
03.75.Kk - Dynamic properties of condensates; collective and hydrodynamic excitations, superfluid flow.
05.60.Gg - Quantum transport.
67.10.Jn - Transport properties and hydrodynamics.

© EPLA 2008