Berlin 2015 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
TT: Fachverband Tiefe Temperaturen
TT 69: Other Low Temperature Topics: Cold Atomic Gases
TT 69.3: Vortrag
Mittwoch, 18. März 2015, 15:30–15:45, A 053
Many-Body Anderson Localization of BECs in the Bose-Hubbard Model — •Roman Katzer1, Cord Müller2, and Johann Kroha1 — 1Universität Bonn — 2Université de Nice, France
We have developed the transport theory for a Bose gas in the disordered Bose-Hubbard model in the regime of strong interactions, i.e. in the vicinity of the Mott lobes of vanishing Bose-Einstein condensate (BEC) amplitude. In contrast to previous approaches, we consider the Bose glass not as a state with vanishing averaged BEC amplitude with finite compressibility, but as the phase with finite average BEC amplitude but vanishing superfluid transport due to many-body Anderson localization of the interacting BEC wave functions and their many-body excitations. The theory is based on a calculation of the local many-body ground and excited states within a stochastic mean-field theory, treating the on-site Hubbard interaction exactly by diagonalizing the local part of the Bose-Hubbard Hamitonian in Fock space. Non-local effects of the interaction are neglected, analogous to Dynamical Mean-Field Theory. The transport theory for these hopping many-body states, including quantum interference processes ("Cooperons") is formulated as a generalization of the self-consistent theory of Anderson localization. The theory describes semiquantitatively the Mott localized phase ("Mott lobes"), the superfluid phase and the Bose glass phase as well as the respective phase transitions. In particular, the theory obeys the theorem of inclusions which states that in a disordered system there is no direct transition from the Mott phase to the superfluid phase.