We report the creation of dual-species Bose-Einstein condensates (BECs) of ${}^{23}\mathrm{Na}$ and ${}^{41}\mathrm{K}$. Favorable background scattering lengths enable efficient sympathetic cooling of ${}^{41}\mathrm{K}$ via forced evaporative cooling of ${}^{23}\mathrm{Na}$ 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 $3\times {10}^5 {}^{23}\mathrm{Na}$ atoms surrounding $5\times {10}^4 {}^{41}\mathrm{K}$ 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 ${}^{23}\mathrm{Na}{}^{41}\mathrm{K}$ molecules as well as the exploration of many-body physics in bosonic ${}^{23}\mathrm{Na}\text{−}{}^{41}\mathrm{K}$ mixtures.

• Received 13 December 2023
• Accepted 23 January 2024

DOI:https://doi.org/10.1103/PhysRevResearch.6.013183

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Published by the American Physical Society