Creation of Ultracold Rb 87 Cs 133 Molecules in the Rovibrational Ground State

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 $hcifmmodetimeselsetexttimesfi{}3811.576(1)text{ }text{ }{mathrm{cm}}^{ensuremath{-}1}$ and the $|{v}^{ensuremath{‘}ensuremath{‘}}=0,{J}^{ensuremath{‘}ensuremath{‘}}=0⟩$ to $|{v}^{ensuremath{‘}ensuremath{‘}}=0,{J}^{ensuremath{‘}ensuremath{‘}}=2⟩$ splitting to be $hifmmodetimeselsetexttimesfi{}2940.09(6)text{ }text{ }mathrm{MHz}$. 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.