1. Physics Colloquium

    "Nanokelvin condensed-matter physics with atomic mixtures in optical lattices"

    Presented by Dominik Schneble, Stony Brook University

    Tuesday, February 25, 2014, 3:30 pm
    Large Seminar Room, Bldg. 510

    Hosted by: Peter Petreczky

    Ultracold atomic gases allow for a wide range of studies at the boundary between atomic physics and condensed-matter physics. In particular, it is possible to confine atoms, cooled down to nanokelvins, in periodic potential landscapes generated by interfering laser beams. The behavior of atoms in these so-called optical lattices mimics that of electrons in conventional solids, but at lattice periods that are three orders of magnitude larger, and with complete control over all relevant parameters in a defect-free environment. — In my talk, I will give a short introduction to the field and its techniques, and will then discuss three recent experiments with mixtures of bosonic atoms in optical lattices whose depth can be independently controlled for each component. In one of the experiments, which focused on the diffraction of atomic matter waves, we observed a novel type of atomic four-wave mixing, linking spin and momentum. A second experiment explored the scattering of atoms from an artificial atomic crystal. We observed inelastic excitations, as well as Bragg processes that revealed the crystal's spatial structure, in some analogy to neutron diffraction from a conventional solid. A third experiment investigated a 1D gas subject to disorder that was introduced via localized atomic impurities. We observed an insulating, gapless phase consistent with the formation of a Bose glass, in which the correlation properties of the disorder were seen to play an important role.