Possibility of an Optically-Trapped Bose-Einstein Condensation

We propose a novel gravito-optical atom trap composed of a blue-detuned, conical dark-hollow-beam propagating upward and the gravity field. When cold atoms are loaded into the conical dark-hollow-beam from a magnetic-optical trap and bounce inside the hollow beam, they experience an efficient hollow-beam induced Sisyphus cooling and repurnping-beam induced geometric cooling. Our investigation shows that an ultracold and dense ⁸⁷Rb atomic sample with an equilibrium 3D temperature of about 1μK can be obtained and the appearance of an optically-trapped Bose-Einstein condensation may be possible in this pure optical trap.