2008/09/09 by U. Schneider, L. Hackermuller, S. Will +6 · 1 citation
Physics and Astronomy · #cond-mat.str-el
paper · pdf · doi:10.1126/science.1165449
published as Science, Vol. 322, p.1520-1525 (2008) · 21 pages, 5 figures and additional supporting material
arxiv created 2008/09/09 · arxiv updated 2010/04/06
The fermionic Hubbard model plays a fundamental role in the description of strongly correlated materials. Here we report on the realization of this Hamiltonian using a repulsively interacting spin mixture of ultracold 40K atoms in a 3D optical lattice. We have implemented a new method to directly measure the compressibility of the quantum gas in the trap using in-situ imaging and independent control of external confinement and lattice depth. Together with a comparison to ab-initio Dynamical Mean Field Theory calculations, we show how the system evolves for increasing confinement from a compressible dilute metal over a strongly-interacting Fermi liquid into a band insulating state. For strong interactions, we find evidence for an emergent incompressible Mott insulating phase.