1995/08/28 by C. C. Bradley, C. A. Sackett, J. J. Tollett +1 · 23 citations
Physics and Astronomy · Chemistry · #Cold Atom Physics and Bose-Einstein Condensates #Spectroscopy and Laser Applications #Advanced Frequency and Time Standards
paper · doi:10.1103/physrevlett.75.1687
openalex publication_date 1995/08/28 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/03
Evidence for Bose-Einstein condensation of a gas of spin-polarized 7Li atoms is reported. Atoms confined to a permanent-magnet trap are laser cooled to 200 \ensuremathμK and are then evaporatively cooled to lower temperatures. Phase-space densities consistent with quantum degeneracy are measured for temperatures in the range of 100 to 400 nK. At these high phase-space densities, diffraction of a probe laser beam is observed. Modeling shows that this diffraction is a sensitive indicator of the presence of a spatially localized condensate. Although measurements of the number of condensate atoms have not been performed, the measured phase-space densities are consistent with a majority of the atoms being in the condensate, for total trap numbers as high as 2\ifmmode×\else\texttimes\fi105 atoms. For 7Li, the spin-triplet s-wave scattering length is known to be negative, corresponding to an attractive interatomic interaction. Previously, Bose-Einstein condensation was predicted not to occur in such a system.