title: Quantum gas of deeply bound ground state molecules.
abstract: Molecular cooling techniques face the hurdle of dissipating translational as well as internal energy in the presence of a rich electronic, vibrational, and rotational energy spectrum. In our experiment, we create a translationally ultracold, dense quantum gas of molecules bound by more than 1000 wave numbers in the electronic ground state. Specifically, we stimulate with 80% efficiency, a two-photon transfer of molecules associated on a Feshbach resonance from a Bose-Einstein condensate of cesium atoms. In the process, the initial loose, long-range electrostatic bond of the Feshbach molecule is coherently transformed into a tight chemical bond. We demonstrate coherence of the transfer in a Ramsey-type experiment and show that the molecular sample is not heated during the transfer. Our results show that the preparation of a quantum gas of molecules in specific rovibrational states is possible and that the creation of a Bose-Einstein condensate of molecules in their rovibronic ground state is within reach.
authors: Institut für Experimental physik und Zentrum für Quantenphysik, Universität Innsbruck, Technikerstrasse 25, 6020 Innsbruck, Austria. johann.danzl@uibk.ac.at
authors: Johann G
authors: JG
authors: Danzl
authors: Elmar
authors: E
authors: Haller
authors: Mattias
authors: M
authors: Gustavsson
authors: Manfred J
authors: MJ
authors: Mark
authors: Russell
authors: R
authors: Hart
authors: Nadia
authors: N
authors: Bouloufa
authors: Olivier
authors: O
authors: Dulieu
authors: Helmut
authors: H
authors: Ritsch
authors: Hanns-Christoph
authors: HC
authors: Nägerl