Researchers at Universität Innsbruck in Austria have created the first Bose-Einstein condensate of cesium using optical cooling and trapping techniques. They reported their achievement in the Dec. 5 issue of Sciencexpress.
To produce the condensate, they employed two crossed 100-W beams of 10.6-µm CO₂ laser radiation as an optical trap, into which they loaded approximately 20 million ¹³³Cs atoms from a standard magneto-optical trap. After an initial cooling step, they created a dimple in the potential well of the trap with a 1064-nm ytterbium-doped fiber laser. By turning off one of the CO₂ laser beams and applying evaporative cooling by ramping down the power of the fiber laser, they produced nearly pure condensates of 16,000 atoms.