EUROCORES_Quantum-degenerate dipolar gases of bialkali molecules_1. Call_EuroQUAM (QuDipMol)

This proposal is part of a European Collaborative Research project of nine contributing groups with the objective to create, investigate and control for the first time a dipolar quantum gas formed by heteronuclear bialkali molecules. Ideally, all molecules in the gas are charac-terized by a single, identical rotational, vibrational and translational quantum state, which is achieved by synthesizing the molecules from atomic quantum gases using light fields (photo-association) and magnetic fields (Feshbach linking). Atom-dimer and dimer-dimer scattering will be investigated in great detail in order to identify routes towards control of molecular col-lisions in a many- body system (ultracold chemistry), and effects of the interactions on the dynamics of the polar quantum gas will be explored. A quantum gas of dipolar molecules represents a many-body system of increased complexity while allowing, in principle, full con-trol over all external and internal (spin-) degrees of freedom. The strength and the orientation of the interaction can be tuned by externally applied electric fields. Quantum gases with exter-nally controllable dipolar interactions are expected to play a major role in condensed matter physics, in ultracold coherent chemistry, and possibly in quantum information processing and for precision measurements. In brief the main objectives of this contribution to the collaborative research project will be to produce ro-vibrational ground state RbCs molecules, to test for ultracold scattering processes and chemical reactions for dipolar molecules, and to perform first tests of the various quantum phases as a result of the dipolar interaction. Our approach to producing quantum gases of RbCs molecules in the ro-vibrational ground state relies on lattice- based Feshbach association from a double species BEC with subsequent optical transfer. This approach in principle combines high association and transfer efficiency with high phase space densities inherited from the initial atomic BECs. Previously, we exten-sively tested this technique in our lab to produce homonuclear molecules (see e.g. J. Herbig et al., Science 301, 1510 (2003)). The techniques available in our lab for both the case of Rb or Cs will now be applied and extended within this project to the Rb-Cs system. We will search for and investigate Rb-Cs Feshbach resonances to determine the Rb-Cs scattering properties. We will then associate Rb-Cs molecules at high phase space densities by means of a suitable Feshbach resonance. We will identify an optical transfer process into the ro-vibrational ground state. Lattice-based Feshbach association and subsequent transfer will then give high conversion efficiencies from atoms to ro-vibrational ground state molecules. Upon "melting" of the lattice a dipolar quantum gas should form. First tests will address the long-range dipolar interaction. It is expected to strongly modify the ground state and collective excitations of the dipolar condensate. The optical lattice can be used to probe the various theoretically proposed quantum phases.