Merging two immiscible BECs of Rb and Cs for optimized production of RbCs ground-state molecules

Full text: Ultracold dipolar particles are a unique tool for addressing fundamental questions in condensed matter physics, quantum simulation, precision spectroscopy or ultracold chemistry. The goal of our work is the optimized production and perfect control of all degrees of freedom of ultracold rovibronic ground-state RbCs molecules. We are starting with two immiscible BECs of Rb and Cs that are spatially separated. With the aid of an optical lattice we prevent three-body loss by first ramping up the lattice to achieve a Mott insulator (MI) state of Cs with exactly one Cs atom per site while the spatially separated Rb ensemble is still in the superfluid regime. We adiabatically change the experimental parameters so that we can move the superfluid Rb cloud on top of the Cs atoms and attach exactly one Rb atom to a Cs atom by tuning the interspecies scattering properties. Following the approach that has been successfully demonstrated in our group we plan to finally create weakly bound molecules by exploiting a Feshbach resonance and subsequently transfer the molecules into the rovibronic ground state with the STIRAP technique. In this work report on the optimized technique of merging and show data of coexisting SF and MI states of different atomic species in the same lattice. (author)