Continuous Loading of Ultracold Ground-State 85Rb2 Molecules in a Dipole Trap Using a Single Light Beam.

We have developed an approach to continuously load ultracold 85Rb2 vibrational ground-state molecules into a crossed optical dipole trap from a magneto-optical trap. The technique relies on a single high-power light beam with a broad spectrum superimposed onto a narrow peak at an energy of about 9400 cm-1. This single laser source performs all the required steps: the short-range photoassociation creating ground-state molecules after radiative emission, the cooling of the molecular vibrational population down to the lowest vibrational level vX=0, and the optical trapping of these molecules. Furthermore, we probe by depletion spectroscopy and determine that 75% of the vX=0 ground-state molecules are in the three lowest rotational levels JX=0, 1, 2. The lifetime of the ultracold molecules in the optical dipole trap is limited to about 70 ms by off-resonant light scattering. The proposed technique opens perspectives for the formation of new molecular species in the ultracold domain, which are not yet accessible by well-established approaches. [ABSTRACT FROM AUTHOR]