Output from Bose condensates in tunnel arrays: the role of mean-field interactions and of transverse confinement

We present numerical studies of atomic transport in 3D and 1D models for 3 mode-locked, pulsed atom laser as realized by Anderson and Kasevich [Scienc e 281 (1998) 1686] using an elongated Bose condensate of Rb-87 atoms poured into 3 vertical optical lattice. From our 3D results we ascertain in a qua ntitative manner the role of mean-field interactions in determining the sha pe and the size of the pulses in the case of Gaussian transverse confinemen t. By comparison with 1D simulations we single out a best-performing 1D red uction of the mean-field interactions, which yields quantitatively useful p redictions for all main features of the matter output. (C) 2000 Elsevier Sc ience B.V. All rights reserved.