Study of impurities immersed in a trapped Bose-Einstein condensate*

Florian Meinert, K. S. Kleinbach, Felix B. Engel +3 more

Zoe Z. Yan, Yiqi Ni, Alexander Chuang +5 more

Zoe Z. Yan, Yiqi Ni, Carsten Robens +1 more

Fernando Cucchietti, Eddy Timmermans

A neutral impurity atom immersed in a dilute Bose-Einstein condensate (BEC) can have a bound ground state in which the impurity is self-localized. In this polaronlike state, the impurity distorts the density of the surrounding BEC, thereby creating the self-trapping potential minimum. We describe the self-localization in a strong-coupling approach.

R. G. Lena

M. Bruderer, W. Bao, D. Jaksch

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 β ⋆ . 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.