Hannover 2010 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 21: Poster I
Q 21.16: Poster
Dienstag, 9. März 2010, 16:00–19:00, Lichthof
Fermionic quantum gases with tunable interactions in optical lattices — •Michael Schreiber1, Ulrich Schneider1, Jens Philipp Ronzheimer1, Lucia Hackermüller2, Thorsten Best3, Sebastian Will1, Simon Braun1, Tim Rom1, Kin Chung Fong4, and Immanuel Bloch1 — 1Ludwig-Maximilians-Universität München — 2University of Nottingham, UK — 3Albert-Ludwig Universität Freiburg — 4Caltech, Pasadena, USA
Fermionic atoms in optical lattices form a very rich many-body system that can serve as a quantum simulator for condensed matter physics. The atoms implement the Fermi Hubbard Hamiltonian with high experimental control over the relevant parameters.
In our system we sympathetically cool 87Rb and 40K in an optically plugged quadrupole trap and an optical dipole trap. After evaporation, a balanced spin mixture of 40K atoms, whose interactions can be changed using a Feshbach resonance, is loaded into a blue-detuned optical lattice.
In the case of repulsive interactions we observe a transition from compressible, metallic states over Mott-insulating to band insulating states for increasing harmonic confinements. On the attractive side we investigate an anomalous expansion, which is related to the pseudogap phase, when the interaction becomes strongly attractive. In addition we study the free expansion of a band insulator in a homogeneous lattice and identify different regimes ranging from ballistic expansion to diffusion dynamics. The latter can effectively suppress the expansion of the high density core of the cloud.