2013/04/30 by Andrew T. Grier, Igor Ferrier-Barbut, Benno S. Rem +4 · 1 citation
Physics and Astronomy · #cond-mat.quant-gas #physics.atom-ph
paper · pdf · doi:10.1103/physreva.87.063411
8 pages, 8 figures; submitted to Phys. Rev. A; V2 contains edits in response to referee's comments
arxiv created 2013/06/04 · arxiv updated 2013/06/19
Following the bichromatic sub-Doppler cooling scheme on the D1 line of 40K recently demonstrated in (Fernandes et al. 2012), we introduce a similar technique for 7Li atoms and obtain temperatures of 60 uK while capturing all of the 5x108 atoms present from the previous stage. We investigate the influence of the detuning between the the two cooling frequencies and observe a threefold decrease of the temperature when the Raman condition is fulfilled. We interpret this effect as arising from extra cooling due to long-lived coherences between hyperfine states. Solving the optical Bloch equations for a simplified, Λ-type three-level system we identify the presence of an efficient cooling force near the Raman condition. After transfer into a quadrupole magnetic trap, we measure a phase space density of ~10-5. This laser cooling offers a promising route for fast evaporation of lithium atoms to quantum degeneracy in optical or magnetic traps.