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Hannover 2016 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 58: Poster: Quantum Optics and Photonics IV

Q 58.67: Poster

Thursday, March 3, 2016, 16:30–19:00, Empore Lichthof

Realization of the ionic Hubbard model with ultracold fermions on optical latticesMichael Messer1, •Rémi Desbuquois1, Thomas Uehlinger1, Gregor Jotzu1, Frederik Görg1, Sebastian Huber2, Daniel Greif1,3, and Tilman Esslinger11Institute 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.

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