Possibility of an optically-trapped Bose-Einstein condensation

We propose a novel gravito-optical atom trap composed of a blue-detuned, co nical 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 repumping-beam induced geometric cooling . Our investigation shows that an ultracold and dense Rb-87 atomic sample w ith an equilibrium 30 temperature of about 1 mu K can be obtained and the a ppearance of an optically-trapped Bose-Einstein condensation may be possibl e in this pure optical trap.