Transport of cold atoms in optical lattices

The work discusses transport of cold atoms in optical lattices. Two related but different problems are considered: interacting Bose atoms subject to a static field (i.e., the atoms in a tilted lattice); and non-interacting atoms in a tilted lattice in the presence of a buffer gas. For these two systems we found, respectively: periodic, quasiperiodic, or decaying Bloch oscillations, as it depends on the strength of atom-atom interactions and the magnitude of the static field; diffusive directed current of atoms, similar to the electron current in ordinary conductors.