Hannover 2016 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 11: Poster: Quantum Optics and Photonics I
Q 11.17: Poster
Montag, 29. Februar 2016, 16:30–19:00, Empore Lichthof
Precision two-color spectroscopy of long-range ground-state vibrational levels in ultracold 40Ca — Veit P. Dahlke1, •Evgenij Pachomow1, Eberhard Tiemann2, Fritz Riehle1, and Uwe Sterr1 — 1Physikalisch-Technische Bundesanstalt (PTB), Bundesallee 100, 38116 Braunschweig — 2Institut für Quantenoptik, Leibniz-Universität Hannover, Welfengarten 1, 30167 Hannover
We have measured the three most weakly bound ground state vibrational levels in the X 1Σg+ potential of 40Ca2, using two-colour photoassociation with different intermediate levels in the a 3Σu+, c 3Πg exited state potential. We have interrogated cold ensembles of about 105 calcium atoms trapped in a crossed dipole trap at temperatures of approximately 1 µ K. The unperturbed binding energies have been measured with kHz accuracy benefiting from few Hertz linewidth offset-locked tunable lasers and detailed lineshape analysis.
The interaction potential at typical internuclear separations for these weakly bound levels is dominated by the long range coefficients C6, C8 which have been derived using a full quantum computation including information of the inner potential range. Our data also give a precise value for the s-wave scattering length a = 308(10) a0 and is an important step in the implementation of low loss optical Feshbach resonances for alkaline earth metals.