  Bose-Einstein condensates of rubidium atoms are stored in a two-dimensional
periodic dipole force potential, formed by a pair of standing wave laser
fields. The resulting potential consists of a lattice of tightly confining
tubes, each filled with a 1D quantum gas. Tunnel-coupling between neighboring
tubes is controlled by the intensity of the laser fields. By observing the
interference pattern of atoms released from more than 3000 individual lattice
tubes the phase coherence of the coupled quantum gases is studied. The lifetime
of the condensate in the lattice and the dependence of the interference pattern
on the lattice configuration are investigated.
