24 research outputs found
Superfluidity of Interacting Bosonic Mixtures in Optical Lattices
We report the observation of many-body interaction effects for a homonuclear
bosonic mixture in a three-dimensional optical lattice with variable state
dependence along one axis. Near the superfluid-to-Mott insulator transition for
one component, we find that the presence of a second component can reduce the
apparent superfluid coherence, most significantly when it either experiences a
strongly localizing lattice potential or none at all. We examine this effect by
varying the relative populations and lattice depths, and discuss the observed
behavior in view of recent proposals for scattering from impurities and of
atom-phonon coupling for atoms immersed in a superfluid.Comment: 4 pages, 3 figure
Collinear Four-Wave Mixing of Two-Component Matter Waves
We demonstrate atomic four-wave mixing of two-component matter waves in a
collinear geometry. Starting from a single-species Bose-Einstein condensate,
seed and pump modes are prepared through microwave state transfer and
state-selective Kapitza-Dirac diffraction. Four-wave mixing then populates the
initially empty output modes. Simulations based on a coupled-mode expansion of
the Gross-Pitaevskii equation are in very good agreement with the experimental
data. We show that four-wave mixing can play an important role in studies of
bosonic mixtures in optical lattices. Moreover our system should be of interest
in the context of quantum atom optics.Comment: 4 pages, 4 figures; revised version, essentially as publishe