Bose-Einstein condensates in an optical lattice

We calculate the quantum motion of a Bose-Einstein condensate in an optical lattice generated by a standing wave of laser light. We show how to boost a stationary condensate into motion or stop a moving condensate by manipula ting the optical lattice and how to achieve Bloch oscillations of the conde nsate in an accelerating optical lattice. We show how atomic interactions a ffect these processes and discuss conditions for possible experimental real ization.