  We report on experiments investigating quantum transport and band
interferometry of an atomic Bose-Einstein condensate in an optical lattice with
a two-band miniband structure, realized with a Fourier-synthesized optical
lattice potential. Bloch-Zener oscillations, the coherent superposition of
Bloch oscillations and Landau-Zener tunneling between the two bands are
observed. When the relative phase between paths in different bands is varied,
an interference signal is observed, demonstrating the coherence of the dynamics
in the miniband system. Measured fringe patterns of this St\"uckelberg
interferometer allow to interferometrically map out the band structure of the
optical lattice over the full Brillouin zone.
