Experimental investigation of evaporative cooling mixture of bosonic ⁸⁷ Rb and fermionic ⁴⁰ K atoms with microwave and radio frequency radiation

We investigate sympathetic cooling fermions 40K by evaporatively cooling bosonic 87Rb atoms in a magnetic trap with microwave and radio frequency induced evaporations in detail. The mixture of bosonic and fermionic atoms is prepared in their polarized spin states |F = 9/2, mF = 9/2〉 for 40K and |F = 2, mF = 2〉 for 87Rb, which is trapped in Quadrupole—Ioffe—Configuration trap. Comparing microwave with radio frequency evaporatively cooling bosonic 87Rb atoms with sympathetically cooling Fermi gas 40K, we find that the presence of rubidium atoms in the |2, 1〉 Zeeman states, which are generated in the evaporative process, gives rise to a significant loss of 40K due to inelastic collisions. Thus, the rubidium atoms populated in the |2, 1〉 Zeeman states should be removed in order to effectively perform sympathetically cooling 40K with the evaporatively cooled 87Rb atoms.