A K/Rb double BEC


We have realized a double-species Bose-Einstein Condensate of 87Rb-41K both in the F=2, mF=2 hyperfine states. The preparation of the superfluid mixtures involves different cooling stages. After a double-MOT phase we transfer the mixture in a magnetic quadrupole field where Rb is evaporated by a microwave radiation resonant on the (F=2, mF=2) - (F=1, mF=1) transition while K is sympathetically cooled by thermal contact with Rb. When the temperature is low enough, we transfer the mixture in a crossed optical trap through an intermediate stage of a hybrid magneto-optical trapping potential. The last stage of cooling is performed by pure optical evaporation in the crossed optical potential. At the end of our typical experimental runs we produce pure condensates of 6×104 atoms for both atomic species.