An Ultracold Gas of Bosonic $^{23}\textrm{Na}^{39}\textrm{K}$ Ground-State Molecules

TL;DR

This paper reports the creation of ultracold bosonic NaK molecules in their ground state, demonstrating low decay rates and opening avenues for studying differences between fermionic and bosonic molecules.

Contribution

The first coherent transfer of NaK molecules to their rovibrational ground state and analysis of their collisional decay properties.

Findings

Low two-body decay coefficient for molecule-atom collisions.

Successful adiabatic Raman transfer to the ground state.

Potential for comparative studies of fermionic and bosonic molecules.

Abstract

We report the creation of ultracold bosonic dipolar $^{23}\textrm{Na}^{39}\textrm{K}$ molecules in their absolute rovibrational ground state. Starting from weakly bound molecules immersed in an ultracold atomic mixture, we coherently transfer the dimers to the rovibrational ground state using an adiabatic Raman passage. We analyze the two-body decay in a pure molecular sample and in molecule-atom mixtures and find an unexpectedly low two-body decay coefficient for collisions between molecules and $^{39}\textrm{K}$ atoms in a selected hyperfine state. The preparation of bosonic $^{23}\textrm{Na}^{39}\textrm{K}$ molecules opens the way for future comparisons between fermionic and bosonic ultracold ground-state molecules of the same chemical species.