[1] Univ Bremen, ZARM, D-28359 Bremen, Germany
[2] Leibniz Univ Hannover, Inst Quantenopt, D-30167 Hannover, Germany
[3] Humboldt Univ, Inst Phys, D-12489 Berlin, Germany
[4] Univ Hamburg, Inst Laser Phys, D-22761 Hamburg, Germany
[5] Univ Ulm, Inst Quantenphys, D-89081 Ulm, Germany
[6] Univ Ulm, Ctr Integrated Quantum Sci & Technol IQST, D-89081 Ulm, Germany
[7] Midlands Ultracold Atom Res Ctr, Birmingham B15 2TT, W Midlands, England
[8] DLR Inst Raumfahrtsyst, D-28359 Bremen, Germany
[9] Tech Univ Darmstadt, Inst Angew Phys, D-64289 Darmstadt, Germany
[10] Max Planck Inst Quantum Opt, D-80799 Munich, Germany
[11] Univ Munich, Fak Phys, D-80799 Munich, Germany
[12] Univ Saarland, D-66041 Saarbrucken, Germany
[13] Leibniz Inst Hochstfrequenztech, Ferdinand Braun Inst, D-12489 Berlin, Germany
[14] ENS UPMC Paris 6 CNRS, Lab Kastler Brossel, F-75005 Paris, France