Formation of bosonic Na 23 K 41 Feshbach molecules

Ultracold Feshbach molecules are a crucial intermediate step for the creation of quantum degenerate gases of strongly dipolar molecules. After coherent transfer to the rovibrational ground state, these dimers can realize stable dipolar gases with strong, tunable long-range interactions. Here, we report the creation of bosonic Na 23 K 41 Feshbach molecules by radio-frequency (RF) association. An RF pulse applied on the molecular side of an interspecies Feshbach resonance at 73.6(1) G associates up to 1.1 ( 1 ) × 10 4 molecules from a thermal mixture of Na 23 and K 41 atoms. Measurements of the binding energy reveal a broad resonance width of 5.1(2) G, facilitating robust control over interspecies interactions. The molecule lifetime in the presence of background atoms exceeds 2 ms and increases to approximately 7 ms after removal of Na 23 . These results constitute a key step toward the production of ultracold Na 23 K 41 ground-state molecules and for pursuing shielded evaporative cooling in the dipolar regime.