Creation of Ultracold 87Rb133Cs Molecules in the Rovibrational Ground State

We report the creation of a sample of over 1000 ultracold (RbCs)-Rb-87-Cs-133 molecules in the lowest rovibrational ground state, from an atomic mixture of Rb-87 and Cs-133, 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 x 3811.576(1) cm(-1) and the vertical bar v '' = 0, J '' = 0> to vertical bar v '' = 0, J '' = 2> splitting to be h x 2940.09(6) 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.