Creation of UltracoldRb87Cs133Molecules in the Rovibrational Ground State

Abstract

We report the creation of a sample of over 1000 ultracold ${}^{87}\mathrm{Rb}{}^{133}\mathrm{Cs}$ molecules in the lowest rovibrational ground state, from an atomic mixture of ${}^{87}\mathrm{Rb}$ and ${}^{133}\mathrm{Cs}$, by magnetoassociation on an interspecies Feshbach resonance followed by stimulated Raman adiabatic passage (STIRAP). We measure the binding energy of the RbCs molecule to be $hc\times 3811.576(1){\mathrm{cm}}^{-1}$ and the $|v^{\prime \prime }=0,J^{\prime \prime }=0⟩$ to $|v^{\prime \prime }=0,J^{\prime \prime }=2⟩$ splitting to be $h\times 2940.09(6)\mathrm{MHz}$. Stark spectroscopy of the rovibrational ground state yields an electric dipole moment of 1.225(3)(8) D, where the values in parentheses are the statistical and systematic uncertainties, respectively. We can access a space-fixed dipole moment of 0.355(2)(4) D, which is substantially higher than in previous work.