Hannover 2016 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 58: Poster: Quantum Optics and Photonics IV
Q 58.67: Poster
Donnerstag, 3. März 2016, 16:30–19:00, Empore Lichthof
Realization of the ionic Hubbard model with ultracold fermions on optical lattices — Michael Messer1, •Rémi Desbuquois1, Thomas Uehlinger1, Gregor Jotzu1, Frederik Görg1, Sebastian Huber2, Daniel Greif1,3, and Tilman Esslinger1 — 1Institute for Quantum Electronics, ETH Zurich, 8093 Zurich, Switzerland — 2Institute for Theoretical Physics, ETH Zurich, 8093 Zurich, Switzerland — 3Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
Ultracold atoms in optical lattices constitute a tool of choice to realize the Fermi-Hubbard model. Previous experiment showed that, by increasing the on-site repulsive interactions, a gap opens in the excitation spectrum and the system becomes progressively a Mott insulator. A more simple band insulator appears in half filled lattices when a staggered energy offset is introduced. There, the ground state possesses charge density-wave ordering. The competition of both phenomena constitute the ionic Hubbard model, which we experimentally realize by loading a two-component interacting Fermi gas into an optical lattice with a staggered energy offset on alternating sites. The underlying density order of the ground state is revealed through the correlations in the noise of the measured momentum distribution. For a large energy offset, we observe a charge density-wave ordering, which is suppressed as the on-site interactions are increased. To further elucidate the nature of the ground state, we measure the double occupancy of lattice sites and show a gapped charge excitation spectrum for a wide range of parameters.