Abstract

The manipulation of ultracold fermionic and bosonic quantum gases in optical lattices permits access to a wide field of exciting experiments ranging from the investigation and simulation of solid state physics to quantum computing and ultracold chemistry. In our appartus we sympathetically cool 40K and 87Rb atoms in a magnetic quadrupole trap, transfer them to a crossed optical trap and cool both species to quantum degeneracy. Subsequently we load pure K samples or K / Rb mixtures into a blue detuned three dimensional optical lattice. The combination of a red detuned dipole trap with a blue detuned optical lattice allows us to vary the external confinement while leaving the lattice potential unchanged. We use this feature to study the transit from a metallic phase to a band insulating phase for a single spin species or for a spin mixture. For the Rb / K mixtures we control the interaction strength to search for ways to efficiently K / Rb atom pairs on the lattice sites, which is an important prerequisite for experiments with heteronuclear molecules.