Formation of deeply bound molecules via chainwise adiabatic passage

Abstract

We suggest and analyze a technique for efficient and robust creation of dense ultracold molecular ensembles in their ground rovibrational state. In our approach a molecule is brought to the ground state through a series of intermediate vibrational states via a multistate chainwise stimulated Raman adiabatic passage technique. We study the influence of the intermediate states decay on the transfer process and suggest an approach that minimizes the population of these states, resulting in a maximal transfer efficiency. As an example, we analyze the formation of $^{87}\mathrm{Rb}_{2}$ starting from an initial Feshbach molecular state and taking into account major decay mechanisms due to inelastic atom-molecule and molecule-molecule collisions. Numerical analysis suggests a transfer efficiency $g90%$, even in the presence of strong collisional relaxation as are present in a high density atomic gas.