Optical quenching of metastable magnesium

Nils Rehbein, Tanja E. Mehlstäubler, Jochen Keupp, Karsten Moldenhauer, Ernst M. Rasel, Wolfgang Ertmer, Albane Douillet, Volker Michels, Sergey G. Porsev, Andrei Derevianko, Charlotte Froese Fischer, Georgio I. Tachiev (+1 others)
2007 Physical Review A. Atomic, Molecular, and Optical Physics  
Doppler cooling on narrow transitions has become a crucial technique for preparing ultracold samples of alkaline-earth-metal and alkaline-earth-metal-like atoms. For lighter species, such as calcium and magnesium, this technique relies on artificial broadening ͑quenching͒ of the upper level of the narrow line. We report on quenching experiments on a 24 Mg atomic beam. The branching ratio of the ͑3s4s͒ 1 S 0 state was determined to be ␤ = ͑1.33± 0.53͒ ϫ 10 −5 from the measured quenching
more » ... y. The branching ratio combined with the known linewidth of this state yields a transition rate for ͑3s3p͒ 3 P 1 → ͑3s4s͒ 1 S 0 of ⌫ 23 = 283± 114 s −1 , i.e., one order of magnitude smaller than estimated from semiempirical data. We have applied different numerical approaches, including ab initio relativistic many-body calculations, to compute the transition probabilities of the ͑3s3p͒ 3 P 1 → ͑3s4s͒ 1 S 0 and ͑3s3p͒ 1 P 1 → ͑3s4s͒ 1 S 0 transitions. The results are in good agreement with our experimental observation. With the measured branching ratio, we expect a transfer efficiency of Dopplercooled atoms into a quench magneto-optical trap ͑QuenchMOT͒ of approximately 1% for our experimental parameters. According to our simulations, the transfer efficiency can be increased by one order of magnitude for lower ensemble temperatures as recently demonstrated by two-photon cooling in our uv MOT.
doi:10.1103/physreva.76.043406 fatcat:am7x3jwb6ba4xgmynpscm6lyzq