  We study the dynamics of Bose-Einstein condensates in tilted and driven
optical superlattices. For a bichromatic lattice, each Bloch band split up into
two minibands such that the dynamics is governed by the interplay of Bloch
oscillations and transitions between the bands. Thus, bichromatic potentials
provide an excellent model system for the study of nonlinear Landau-Zener
tunneling and allow for a variety of applications in matter wave interferometry
and quantum metrology. In the present paper we investigate the coherent
dynamics of an interacting Bose-Einstein condensate as well as its stability.
Different mechanisms of instability are discussed, which lead to a rapid
depletion of the condensate.
