All-optical production of chromium Bose-Einstein condensates

Abstract

We report on the production of $^{52}\mathrm{Cr}$ Bose-Einstein condensates with an all-optical method. We first load $5\ifmmode\times\else\texttimes\fi{}{10}^{6}$ 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 $^{5}S_{2}$ 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 ($35\phantom{\rule{0.3em}{0ex}}\mathrm{ms}$ $1∕e$ time) and the use of relatively fast evaporative ramps allow us to obtain in $20\phantom{\rule{0.3em}{0ex}}\mathrm{s}$ about $15\phantom{\rule{0.2em}{0ex}}000$ atoms in an almost pure condensate.