  We have loaded Bose-Einstein condensates into one-dimensional, off-resonant
optical lattices and accelerated them by chirping the frequency difference
between the two lattice beams. For small values of the lattice well-depth,
Bloch oscillations were observed. Landau-Zener tunneling out of the lowest
lattice band, leading to a breakdown of the oscillations, was also studied. In
order to allow in-trap measurements of these phenomena, we dynamically
compensated for the intrinsic micromotion of the atoms in our time-orbiting
potential trap.
