Ultracold-molecule production by laser-cooled atom photoassociation

We propose a method for copiously producing ultracold ground electronic-state molecules by two-photon absorption to a Rydberg molecular level (that spontaneously radiates to the ground molecular state) during collisions of ultracold atoms in a laser trap. Using the Na₂ molecule as an example, the sequential two-photon absorption is via an intermediate high-lying vibrational level of the excited 1g state and results in the formation of a given vibrational level of a ¹Πᵤ Rydberg molecular state. Realistic calculations demonstrating the validity of the method are presented.