Feshbach resonances in an ultracold mixture of 87Rb and 40K

We report the experimental preparations of the absolute ground states of Rb-87 and K-40 atoms (vertical bar F = 1, m(F) = 1 > + vertical bar F = 9/2, m(F) = -9/2 >) by means of the radio-frequency and microwave adiabatic rapid passages, and the observation of magnetic Feshbach resonances in an ultracold mixture of bosonic Rb-87 and fermionic K-40 atoms between 0 T and 6.0 x 10(-2) T, including 7 homonuclear and 4 heteronuclear Feshbach resonances. The resonances are identified by the abrupt trap loss of atoms induced by the strong inelastic three-body collisions. These Feshbach resonances should enable the experimental control of interspecies interactions.