All-optical production of chromium Bose-Einstein condensates

We report on the production of ⁵²Cr Bose-Einstein condensates with an all-optical method. 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 (350.3em0exms $1∕e$ time) and the use of relatively fast evaporative ramps allow us to obtain in 200.3em0exs about 150.2em0ex000 atoms in an almost pure condensate.