All-Optical Formation of an Atomic Bose-Einstein Condensate

We have created a Bose-Einstein condensate (BEC) of ⁸⁷Rb atoms directly in an optical trap. We employ a quasielectrostatic dipole force trap formed by two crossed CO₂ laser beams. Loading directly from a sub-Doppler laser-cooled cloud of atoms results in initial phase space densities of ~1/200. Evaporatively cooling through the BEC transition is achieved by lowering the power in the trapping beams over ~2 s. The resulting condensates are F = 1 spinors with 3.5×10⁴ atoms distributed between the m_F = (-1,0,1) states.