Coherent atomic beam generator

The availability of ultracold atoms, as well as the recent demonstration of Bose condensation for trapped alkali, have lead to renewed efforts to produce a coherent atomic beam generator, or 'atom laser.' This paper discusses such a scheme based on a driven-damped sample of ultracold atoms in an extended, quasi-one-dimensional cavity. An important aspect of this scheme is that the atoms are subjected to the near-resonant dipole-dipole interaction, whose collisional cross section can be tuned over several orders of magnitude by varying the atom-field detuning and the precise geometry of the cavity. In addition, for transversally well confined atoms the dipole-dipole selection rules lead to a major simplification in that only two quantized levels of atomic motion need be considered explicitly, the other levels being inadequately treated as two thermal reservoirs.