Eur. Phys. J. B 56, 199-203 (2007)
https://doi.org/10.1140/epjb/e2007-00118-3

Quantum phase transitions in the bosonic single-impurity Anderson model

Theoretische Physik III, Elektronische Korrelationen und Magnetismus, Institut für Physik, Universität Augsburg, 86135 Augsburg, Germany

Corresponding author: ^a ralf.bulla@physik.uni-augsburg.de

Received: 15 September 2006
Revised: 29 March 2007
Published online: 4 May 2007

Abstract

We consider a quantum impurity model in which a bosonic impurity level is coupled to a non-interacting bosonic bath, with the bosons at the impurity site subject to a local Coulomb repulsion U. Numerical renormalization group calculations for this bosonic single-impurity Anderson model reveal a zero-temperature phase diagram where Mott phases with reduced charge fluctuations are separated from a Bose-Einstein condensed phase by lines of quantum critical points. We discuss possible realizations of this model, such as atomic quantum dots in optical lattices. Furthermore, the bosonic single-impurity Anderson model appears as an effective impurity model in a dynamical mean-field theory of the Bose-Hubbard model.