All-optical production of chromium Bose-Einstein condensates

We report on the production of 52Cr Bose-Einstein condensates with an all-optical method.
arXiv:0712.3521 (2007) / Phys. Rev. A 77, 061601(R) (2008)

We first load 5×106 metastable chromium atoms in a one-dimensional (1D) far-off-resonance optical trap (FORT) from a magneto-optical trap, by combining the use of radio-frequency sweeps and depumping toward the 5𝑆2 state.

The atoms are then pumped to the absolute ground state, and transferred into a crossed FORT in which they are evaporated. The fast loading of the 1D FORT (35ms 1/𝑒 time) and the use of relatively fast evaporative ramps allow us to obtain in 20s about 15000 atoms in an almost pure condensate.

Analysis of the experimental free expansion of an almost pure BEC. The Thomas Fermi radii along y (diamonds) and z (triangles) are deduced from absorption pictures.