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Q: Quantenoptik
Q 17: Poster: Cooling and Trapping
Q 17.22: Poster
Wednesday, April 4, 2001, 12:30–15:00, AT2
Sagnac Interferometry with Cold Atoms — •Tanja E. Mehlstäubler, Jochen Keupp, Hung Ly, Albane Douillet, Ernst M. Rasel, and Wolfgang Ertmer — Institut für Quantenoptik, Universität Hannover, Welfengarten 1, 30167 Hannover, Germany
Temperatures of a few milli-Kelvin corresponding to the classical Doppler limit defined the state-of-the-art of cooling alkaline earth atoms such as Mg and Ca. We present a new cooling technique that employs a two-step excitation (cooling and quenching) on so-called ”forbidden” transitions, allowing a decrease in temperature by 2 orders of magnitude. For the case of magnesium a 3-dimensional Monte-Carlo-simulation of the cooling and loading mechanism into a ”quench-MOT” has been performed. According to the simulation 40 % of the atoms trapped in a standard MOT with T ≈ 2 mK can be transfered to the ”quench-MOT” and cooled down to temperatures as low as 10 µK. It could be shown that the implementation requires two blue laser systems each with an output power of P ≈ 100 mW. A stilben dye-laser is available for the quenching transition at 462 nm whereas a novel high power, frequency-doubled Nd:YVO4 laser at 457 nm is currently build up for the cooling. Colder samples of alkaline earth atoms promise an increase in stability and accuracy of high precision atom-interferometers, essential for optical atomic clocks.