Hannover 2010 – wissenschaftliches Programm
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A: Fachverband Atomphysik
A 27: Ultra-Cold Atoms, Ions and BEC IV / Interaction with VUV and X-Ray Light II (with Q)
A 27.3: Vortrag
Freitag, 12. März 2010, 14:30–14:45, F 303
Optical Trapping of Magnesium — •Matthias Riedmann, Jan Friebe, Temmo Wübbena, André Kulosa, Hrishikesh Kelkar, Sana Amairi, André Pape, Sina Malobabic, Steffen Rühmann, Wolfgang Ertmer, and Ernst-Maria Rasel — Institut für Quantenoptik, Hannover, Germany
Magnesium is an interesting candidate for a future high performance neutral atom optical frequency standard. Long spectroscopy time and therefore high resolution can be reached by confining the atoms in the Lamb-Dicke regime in an optical lattice. Magnesium is challenging because cooling on the strong singlet transition is limited to the Doppler limit of 2 mK. Cooling on narrow lines, a standard technique to reach ultralow temperatures for other alkaline-earth atoms, is not promissing for Mg because of a too narrow intercombination line (31 Hz).
Mg atoms are pre-cooled in a two-stage MOT. Atoms are first trapped on the strong singlet cooling transition and then pumped to the triplet system. There, another MOT operating between the 3P and 3D states is used to further cool and compress the atomic cloud. Atoms that decay to the 3P1 state are repumped while those that decay to the 3P0 are not and can be optically trapped by a 1064 nm dipole trap, which is superimposed with the second MOT. All cooling stages are running coutinously and atoms are accumulated in the dipole trap. The loss chnannel in the second MOT avoids a density limitation and therefore increases the loading to the dipole trap. With this technique, we are able to load up to 9 · 104 atoms to the dipole trap.