Dynamics and spatial order of atoms confined in an optical lattice

Z. Li, Roman V. Krems

Axel Görlitz, Theodor W. Hänsch, Andreas Hemmerich

This paper discusses how Bragg diffraction can be applied to measure the position spread of atomic wave packets localized in the light-induced periodic potential wells of an optical lattice. We describe an observation method which is solely based on monitoring light powers. No hard-to-access system parameters are referred to. We discuss the application of this method in the observation of unusual atomic vibrational modes with a position spread oscillating at twice the fundamental harmonic frequency. We also discuss the influence of the number of trapped atoms on the lattice geometry. We give experimental evidence for a contraction of the optical lattice as the filling factor is increased.

Georg A. Raithel, G. Birkl, William D. Phillips +1 more

Rafael A. Molina, J. Dukelsky, Peter Schmitteckert

Fermionic atoms in two different hyperfine states confined in optical lattices show strong commensurability effects due to the interplay between the atomic density wave ordering and the lattice potential. We show that spatially separated regions of commensurable and incommensurable phases can coexist. The commensurability between the harmonic trap and the lattice sites can be used to control the amplitude of the atomic density waves in the central region of the trap.

William D. Phillips

Michael Köhl, Henning Moritz, Thilo Stöferle +2 more

We have studied interacting and noninteracting quantum degenerate Fermi gases in a three-dimensional optical lattice. We directly image the Fermi surface of the atoms in the lattice by turning off the optical lattice adiabatically. Because of the confining potential, gradual filling of the lattice transforms the system from a normal state into a band insulator. The dynamics of the transition from a band insulator to a normal state is studied, and the time scale is measured to be an order of magnitude larger than the tunneling time in the lattice. Using a Feshbach resonance, we increase the interaction between atoms in two different spin states and dynamically induce a coupling between the lowest energy bands. We observe a shift of this coupling with respect to the Feshbach resonance in free space which is anticipated for strongly confined atoms.