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M. J. Mark,
J. G. Danzl,
E. Haller,
M. Gustavsson,
N. Bouloufa,
O. Dulieu,
H. Salami,
T. Bergeman,
H. Ritsch,
R. Hart,
H.-C. Nägerl
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ABSTRACT: One possible way to produce ultra-cold, high-phase-space-density quantum gases of molecules in the rovibronic ground state
is given by molecule association from quantum-degenerate atomic gases on a Feshbach resonance and subsequent coherent optical
multi-photon transfer into the rovibronic ground state. In ultra-cold samples of Cs2 molecules, we observe two-photon dark resonances that connect the intermediate rovibrational level |v=73,J=2〉 with the rovibrational ground state |v=0,J=0〉 of the singlet X
1
Σ
g
+ ground-state potential. For precise dark resonance spectroscopy we exploit the fact that it is possible to efficiently populate
the level |v=73,J=2〉 by two-photon transfer from the dissociation threshold with the stimulated Raman adiabatic passage (STIRAP) technique.
We find that at least one of the two-photon resonances is sufficiently strong to allow future implementation of coherent STIRAP
transfer of a molecular quantum gas to the rovibrational ground state |v=0,J=0〉.
Applied Physics B 04/2012; 95(2):219-225. · 2.19 Impact Factor
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ABSTRACT: We investigate local three-body correlations for bosonic particles in three dimensions and one dimension as a function of the interaction strength. The three-body correlation function g(3) is determined by measuring the three-body recombination rate in an ultracold gas of Cs atoms. In three dimensions, we measure the dependence of g(3) on the gas parameter in a BEC, finding good agreement with the theoretical prediction accounting for beyond-mean-field effects. In one dimension, we observe a reduction of g(3) by several orders of magnitude upon increasing interactions from the weakly interacting BEC to the strongly interacting Tonks-Girardeau regime, in good agreement with predictions from the Lieb-Liniger model for all strengths of interaction.
Physical Review Letters 12/2011; 107(23):230404. · 7.37 Impact Factor
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ABSTRACT: We perform precision measurements on a Mott-insulator quantum state of ultracold atoms with tunable interactions. We probe the dependence of the superfluid-to-Mott-insulator transition on the interaction strength and explore the limits of the standard Bose-Hubbard model description. By tuning the on-site interaction energies to values comparable to the interband separation, we are able to quantitatively measure number-dependent shifts in the excitation spectrum caused by effective multibody interactions.
Physical Review Letters 10/2011; 107(17):175301. · 7.37 Impact Factor
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ABSTRACT: We report on the control of interaction-induced dephasing of Bloch oscillations for an atomic Bose-Einstein condensate in an optical lattice. We quantify the dephasing in terms of the width of the quasimomentum distribution and measure its dependence on time for different interaction strengths which we control by means of a Feshbach resonance. For minimal interaction, the dephasing time is increased from a few to more than 20 thousand Bloch oscillation periods, allowing us to realize a BEC-based atom interferometer in the noninteracting limit.
Physical Review Letters 03/2008; 100(8):080404. · 7.37 Impact Factor
