Self-trapping of impurities in Bose-Einstein condensates: Strong attractive and repulsive coupling

¹  Clarendon Laboratory, University of Oxford - Parks Road, Oxford OX1 3PU, UK, EU
²  Department of Mathematics and Center for Computational Science and Engineering, National University of Singapore - 117543, Singapore

Corresponding author: m.bruderer@physics.ox.ac.uk

Received: 25 January 2008
Accepted: 9 March 2008

Abstract

We study the interaction-induced localization the so-called self-trapping of a neutral impurity atom immersed in a homogeneous Bose-Einstein condensate (BEC). Based on a Hartree description of the BEC we show that unlike repulsive impurities attractive impurities have a singular ground state in 3d and shrink to a point-like state in 2d as the coupling approaches a critical value . Moreover, we find that the density of the BEC increases markedly in the vicinity of attractive impurities in 1d and 2d, which strongly enhances inelastic collisions between atoms in the BEC. These collisions result in a loss of BEC atoms and possibly of the localized impurity itself.