Formation of Ultracold NaRb Feshbach Molecules

TL;DR

This paper reports the creation of ultracold NaRb Feshbach molecules via magneto-association, achieving a significant number of molecules with a lifetime suitable for future spectroscopy and transfer to stable ground states.

Contribution

Demonstrated the formation of ultracold NaRb Feshbach molecules with detailed measurements of their properties and stability, advancing the field of ultracold molecule research.

Findings

Produced at least 4000 molecules from ultracold mixture

Pure molecules live for approximately 22 ms in optical trap

Measured large closed-channel fraction and binding energy near resonance

Abstract

We report the creation of ultracold bosonic $^{23}$Na$^{87}$Rb Feshbach molecules via magneto-association. By ramping the magnetic field across an interspecies Feshbach resonance, at least 4000 molecules can be produced out of the near degenerate ultracold mixture. Fast loss due to inelastic atom-molecule collisions is observed, which limits the pure molecule number, after residual atoms removal, to 1700. The pure molecule sample can live for 21.8(8) ms in the optical trap, long enough for future molecular spectroscopy studies toward coherently transferring to the singlet ro-vibrational ground state, where these molecules are stable against chemical reaction and have a permanent electric dipole moment of 3.3 Debye. We have also measured the Feshbach molecule's binding energy near the Feshbach resonance by the oscillating magnetic field method and found these molecules have a large closed-channel fraction.