  A new type of matter wave diffraction management is presented that leads to
sub-diffractive soliton-like structures. The proposed management technique uses
two counter-moving, identical periodic potentials (e.g. optical lattices). For
suitable lattice parameters a novel type of atomic band-gap structure appears
in which the effective atomic mass becomes infinite at the lowest edge of an
energy band. This way normal matter-wave diffraction (proportional to the
square of the atomic momentum) is replaced by fourth-order diffraction, and
hence the evolution of the system becomes sub-diffractive.
