Exploring the Fermi-Hubbard model with ultracold Fermions
Prof. Dr. Henning Moritz (Universitaet Hamburg)

Ultracold atoms have proved to be an unique tool to investigate quantum phenomena in a model environment. Recent years have seen a definite trend towards the investigation of strongly correlated quantum phenomena. Here, many of the open questions in strongly correlated quantum physics originate from solid state physics, where the strong repulsion between electrons give rise to surprising properties. A prime example is the Mott insulator, where the suppression of conductivity is a result of interactions and not the consequence of a filled Bloch band. Fermionic quantum gases trapped in an optical lattice offer a very pure realisation of the Hubbard model, giving a new approach to understand the physics of strongly correlated systems. In this talk I will show experiments in which we have realized the Fermi-Hubbard model and the fermionic Hubbard model with ultracold atoms.

In the second part, I will report on high-resolution in situ measurements of density fluctuations in an ultracold Fermi gas. Our measurements show that the density fluctuations in the center of the trap are suppressed for a quantum degenerate gas as compared to a non-degenerate gas, allowing us to observe fermionic antibunching in real space for the first time.