GRAVITATIONAL LASER TRAP FOR ATOMS WITH EVANESCENT-WAVE COOLING

We propose a trap based on an evanescent light wave formed on the surface of a pyramidal hollow in a glass substrate. Alkali atoms repeatedly reflected at the evanescent wave and kept in their lower hyperfine ground state by a weak repumping laser beam can be cooled to recoil-limited temperatures by a Sisyphus and a geometric cooling mechanism, which are connected with spontaneous transitions to the upper hyperfine ground state during the reflections. Numerical simulations for K-39, Rb-85 and Cs-133 predict equilibrium 3D rms momenta of similar to 3.5 HBARk. We estimate the collisional loss rates and show that the trap can produce extremely cold and dense samples of atoms and may even reach the point of Bose-Einstein condensation.