Instability-induced localization of matter waves in moving optical lattices

By using a one-dimensional nonpolynomial nonlinear mean-field model, we numerically analyze the process of the loading of the Bose-Einstein condensate into a moving one-dimensional optical lattice. We demonstrate that the recently observed dynamical instability of the Bloch states of a repulsive condensate in a moving optical lattice can lead to formation of trains of spatially localized wave packets that can be associated with matter-wave gap solitons. We study the characteristic features of this matter-wave localization under realistic conditions by modeling the dynamics of the condensate beyond the onset of dynamical instability.