Atomic localization caused by the asymmetry of the Landau-Zener transitions

The motion of an atomic wave packet in a standing light wave can be described in terms of two periodic potentials. Single atom may perform Landau-Zener (LZ) transitions between these two energy states. In this Letter we have found regimes when atom is localized in the momentum space in the vicinity of its initial momentum. We argue that this localization is caused by the asymmetry of LZ transitions (i.e. probability of tunneling depends on its direction) due to the interference.