Progress in trapping rubidium molecules

We have recently observed the formation of ultracold rubidium molecules in the triplet ground state at a temperature of about 90 μK inside a Rb MOT [1]. The most efficient formation has been found to go through photoassociation to the excited 0g (P3/2) state and successive radiative decay to the a Σu ground state [2]. In this way up to 10 mol/s are produced. These molecules remain in the MOT region for nearly 10 ms before falling due to gravity and to the residual velocity; this actually limits any possible experiment with them. To increase the storage timescale, trapping of the molecules must be obtained. We are setting up an optical dipolar trap using a CO2 laser to confine rubidium molecules. This kind of trap, known as QUEST (quasi-electrostatic trap), has already been successful in trapping cesium molecules [3]. We shall describe the status of our experiment.