Heidelberg 2015 – wissenschaftliches Programm

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MO: Fachverband Molekülphysik

MO 5: Posters 1: Novelties in Molecular Physics

MO 5.16: Poster

Montag, 23. März 2015, 17:00–19:00, C/Foyer

Evidence for long-lived collision complexes in scattering of ultracold ground-state molecules — •Katharina Lauber, Emil Kirilov, Manfred Mark, Florian Meinert, and Hanns-Christoph Nägerl — Institut für Experimentalphysik, Universität Innsbruck, 6020 Innsbruck, Österreich

Ultracold molecules trapped in optical lattice potentials at high densities and prepared in their lowest internal quantum state are an ideal starting point for fundamental studies in physics and chemistry, ranging from novel quantum gas experiments and cold controlled chemistry to quantum simulation. We create ultracold and dense samples of Cs dimer molecules in their rovibrational ground state in an optical lattice with near unity occupation probability at the individual lattice sites. The preparation involves the formation of a Cs Bose-Einstein condensate, the transition to a Mott-insulating state, the formation of Feshbach molecules, and coherent 4-photon ground-state transfer. Lowering the lattice potential along one or two directions allows us to probe the molecules' collisional properties in one- and two-dimensional geometry, respectively. Atoms can also be used as scattering partners. In all cases under investigation we observe rather rapid loss of molecules, in particular when the molecules are in their absolute hyperfine ground state. We attribute such loss to the formation of elastically bound long-lived collision complexes, i.e. the formation of atom-dimer or dimer-dimer two-body complexes, which then undergo a secondary collision with another atom or molecule. We model our data to derive rate coefficients and lifetimes and compare the results to recent predictions.