  We demonstrate finite range binding potentials between pairs of Rydberg atoms
interacting with each other via attractive and repulsive van der Waals
potentials and driven by a microwave field. We show that, using destructive
quantum interference to cancel single-atom Rydberg excitation, the
Rydberg-dimer states can be selectively and coherently populated from the
two-atom ground state. This can be used to realize a two-qubit interaction gate
which is not susceptible to mechanical forces between the atoms and is
therefore immune to motional decoherence.
