Continuous loading of {sup 1}S{sub 0} calcium atoms into an optical dipole trap
- Institut fuer Laser-Physik, Universitaet Hamburg, Luruper Chaussee 149, 22761 Hamburg (Germany)
We demonstrate an efficient scheme for continuous trap loading based upon spatially selective optical pumping. We discuss the case of {sup 1}S{sub 0} calcium atoms in an optical dipole trap (ODT), however, similar strategies should be applicable to a wide range of atomic species, which do not permit efficient conventional trap loading. Our starting point is a moderately cold ({approx_equal}300 {mu}K) and dense ({approx_equal}9x10{sup 9} cm{sup -3}) reservoir of metastable {sup 3}P{sub 2} atoms in a magneto-optic trap (triplet MOT). A focused 532 nm laser beam produces a strongly elongated optical potential for {sup 1}S{sub 0} atoms with up to 350 {mu}K well depth. A weak focused laser beam at 430 nm, carefully superimposed upon the ODT beam, selectively pumps the {sup 3}P{sub 2} atoms inside the capture volume to the singlet state, where they are confined by the ODT. The triplet MOT perpetually refills the capture volume with {sup 3}P{sub 2} atoms, thus providing a continuous stream of cold atoms into the ODT at a rate of 10{sup 7} s{sup -1}. Limited by evaporation loss, in 200 ms we typically load 5x10{sup 5} atoms with 3.5x10{sup 10} cm{sup -3} peak density and axial and radial temperatures of 300 and 85 {mu}K, respectively. After terminating the loading we observe evaporation during 50 ms, typically leaving us with 10{sup 5} atoms with nearly equal radial and axial temperatures close to 40 {mu}K and a peak density of 5x10{sup 11} cm{sup -3}. A simple model is presented, which identifies the relevant physical mechanisms of the loading and decay dynamics. We point out that a comparable scheme could be employed to load a dipole trap with {sup 3}P{sub 0} atoms.
- OSTI ID:
- 21020550
- Journal Information:
- Physical Review. A, Vol. 76, Issue 3; Other Information: DOI: 10.1103/PhysRevA.76.033418; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 1050-2947
- Country of Publication:
- United States
- Language:
- English
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