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 …

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 …