High phase-space density gas of NaCs Feshbach molecules

We report on the creation of ultracold gases of bosonic Feshbach molecules of NaCs. The molecules are associated from overlapping gases of Na and Cs using a Feshbach resonance at 864.12(5) G. We characterize the Feshbach resonance using bound-state spectroscopy, in conjunction with a coupled-channel calculation. By varying the temperature and atom numbers of the initial atomic mixtures, we demonstrate the association of NaCs gases over a wide dynamic range of molecule numbers and temperatures, reaching 70 nK for our coldest systems and a phase-space density near 0.1. This is an important stepping stone for the creation of degenerate gases of strongly dipolar NaCs molecules in their absolute ground state.

Automated summary

This article reports the creation of ultracold gases of bosonic Feshbach molecules of NaCs, which are formed from overlapping gases of Na and Cs using a Feshbach resonance. The crucial parameters such as molecule numbers and temperatures of the associated gases are obtained through experiments. This lays the foundation for the creation of degenerate gases of strongly dipolar NaCs molecules in their absolute ground state.