GRAVITO-OPTICAL TRAP FOR COLD ATOMS WITH DOUGHNUT-HOLLOW BEAM COOLING

We present a simple gravito-optical atom trap consisting of a blue-det uned, conical doughnut-hollow beam and the gravity field. Cold atoms a re loaded into the doughnut-hollow beam from a magnetic-optical trap a nd cooled by Sisyphus cooling and geometric cooling induced by the dou ghnut-hollow beam and a weak repumping beam. We calculate the light-sh ift potential for atoms confined in the doughnut-hollow beam, analyze the cooling and heating mechanisms in the trap and estimate the trap l osses. Our study shows that an ultra-cold atomic sample with an equili brium 3D rms momentum of about 2.5 (h) over bar k (a temperature of si milar to 1 mu K) may be obtained in the trap. (C) 1998 Published by El sevier Science B.V.