Düsseldorf 2007 – scientific programme
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Q: Fachverband Quantenoptik und Photonik
Q 64: Poster Quantengase
Q 64.20: Poster
Thursday, March 22, 2007, 16:30–18:30, Poster C
Localisation and delocalisation of ultracold bosonic atoms in finite optical lattices — •Dirk-Sören Lühmann1, Kai Bongs2, Klaus Sengstock2, and Daniela Pfannkuche1 — 1Institut für Theoretische Physik, Universität Hamburg, Jungiusstr. 9, 20355 Hamburg, Germany — 2Institut für Laser-Physik, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
By tuning the potential of optical lattices from shallow to deep, repulsively interacting bosonic atoms can undergo a quantum phase transition from a superfluid phase to a Mott insulator. The transition was predicted theoretically using the Bose-Hubbard modell [1] and was recently observed experimentally [2]. We have focused on finite quasi one-dimensional lattices which can be treated with great accuracy by exact diagonalisation of the full Hamiltonian in a multiple band eigenbasis. Surprisingly, lattices with few sites show already a very similar behaviour as known macroscopically. The transition from delocalisation to localisation is reflected in the momentum distribution as well as in the energy spectrum and was proved using spatial correlation functions. In deep lattices with non-integer filling factors a precursor of a Bose glass can be observed. Beside the formation of a lowest (gapped) many-particle band the momentum distribution and correlation functions were explored.
[1] D. Jaksch et al., Phys. Rev. Let. 81, 3108 (1998)
[2] M. Greiner et al., Nature 415, 39 (2002)