Expansion of a coherent array of Bose-Einstein condensates - art. no. 220401

We investigate the properties of a coherent array containing about 200 Bose -Einstein condensates produced in a far detuned 1D optical lattice. The den sity profile of the gas, imaged after releasing the trap, provides informat ion about the coherence of the ground-state wave function. The measured ato mic distribution is characterized by interference peaks. The time evolution of the peaks, their relative population, as well as the radial size of the expanding cloud are in good agreement with the predictions of theory. The 2D nature of the trapped condensates and the conditions required to observe the effects of coherence are also discussed.