Dual-species Bose-Einstein condensates of 23Na and 41K with tunable interactions

We report the creation of dual -species Bose-Einstein condensates (BECs) of 23Na and 41K. Favorable background scattering lengths enable efficient sympathetic cooling of 41K via forced evaporative cooling of 23Na in a plugged magnetic trap and an optical dipole trap. The 1/e lifetime of the thermal mixture in the stretched hyperfine state exceeds 5 s in the presence of background scattering. At the end of evaporation, we create dual BECs in the immiscible phase, with about 3 x 105 23Na atoms surrounding 5 x 104 41K atoms. To further enable the tuning of the interspecies interaction strength, we locate multiple Feshbach resonances at magnetic fields up to 100 G. The broadest s -wave resonance located at 73.4(3) G features a favorable width of 1.8(2) G. This work sets the stage for the creation of ultracold gases of strongly dipolar bosonic 23Na 41K molecules as well as the exploration of many -body physics in bosonic 23Na - 41K mixtures.