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Q: Fachverband Quantenoptik und Photonik
Q 68: Quantum Gases: Fermions III
Q 68.7: Vortrag
Freitag, 4. März 2016, 16:00–16:15, e001
Studying the interplay of order and geometry in the Hubbard model with ultracold fermions — Rémi Desbuquois1, •Gregor Jotzu1, Michael Messer1, Thomas Uehlinger1, Frederik Görg1, Sebastian Huber2, Daniel Greif1, and Tilman Esslinger1 — 1Institute for Quantum Electronics, ETH Zurich, 8093 Zurich, Switzerland — 2Institute for Theoretical Physics, ETH Zurich, 8093 Zurich, Switzerland
The geometry of a lattice plays a crucial role in determining the order which can form therein. This shows up in the types of spin-correlations supported by a particular lattice, but can even play a role in the charge/density degree of freedom. In particular, when a symmetry of the system is broken by the lattice, the resulting quantum state is expected to display this broken symmetry.
For example, in the ionic Hubbard model, an energy-offset between neighbouring sites breaks inversion symmetry leading to a charge-density wave. However, strong repulsive interactions can drive the system into a Mott-insulating regime, where the broken symmetry is suppressed in the density-distribution.
Ultracold atoms in optical lattices are well suited for styding the effects of varying the lattice geometry, as both local observables such as the double-occupancy, and long-range observables such as noise-correlations are accessible. In addition, the excitation spectrum of the system can be probed by dynamically modulating the lattice parameters.