Improved intensity-gradient cooling of alkali atoms in pyramidal-hollow-beam gravito-optical trap

Abstract

We propose a novel gravito-optical dipole trap for cold, alkali atoms composed of a blue-detuned, pyramidal-hollow beam propagating upward and the gravity field. When cold atoms from a magneto-optical trap are loaded into the pyramidal-hollow beam (PHB) and bounce inside the PHB, they experience efficient PHB-induced Sisyphus cooling (i.e., intensity-gradient cooling) and repumping-beam-induced geometric cooling. By using Monte-Carlo simulations, we study the dynamic process of the improved intensity-gradient cooling of cold atoms in the PHB gravito-optical trap. Our study shows that an ultracold atomic sample with a temperature of ∼2 μK and a density of 1012-1013 atoms/cm3 can be obtained in our PHB trap. © 2001 Elsevier Science B.V. All rights reserved.