Heidelberg 2015 – scientific programme
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Q: Fachverband Quantenoptik und Photonik
Q 69: Ultracold Atoms and Molecules (with A)
Q 69.5: Talk
Friday, March 27, 2015, 12:00–12:15, B/SR
Improved ground-state scattering length of 40Ca by two-colour photoassociation — •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 second to last weakly bound ground state vibrational level J = 0 in the 1S0 + 1S0 potential of 40Ca2. We used two-colour photoassociation with the intermediate level v′=−1, Ω′=1, J′=1 in the 1S0 + 3P1 potential on a cold ensemble of about 105 calcium atoms trapped in a crossed dipole trap at a temperature of approximately 1 µ K. The photoassociation light is applied via two offset locked precisely tunable lasers. The vibrational level is located 1387.439(9) MHz below the asymptote and corresponds to the v=39, J=0 state.
With the exact determination of this level it becomes possible to derive a more accurate description of the ground state potential which will result in a more precise value for the ground state scattering length. By detecting more bound levels it will be possible to further improve on the accuracy and also enable us to predict the tunability of the scattering length by low-loss optical Feshbach resonances in the case of 40Ca.