Long-range Rydberg-atom–ion molecules of Rb and Cs

We propose a novel type of Rydberg dimer, consisting of a Rydberg-state atom bound to a distant positive ion.The molecule is formed through long-range electric-multipole interaction between the Rydberg atom and the pointlike ion.We present potential energy curves (PECs) that are asymptotically connected with Rydberg nP or nD states of rubidium or cesium.The PECs exhibit deep, long-range wells which support many vibrational states of Rydberg-atom-ion molecules (RAIMs).We consider photoassociation of RAIMs in both the weak and the strong optical-coupling regimes between initial and Rydberg states of the neutral atom.Experimental considerations for the realization of RAIMs are discussed.