Light-assisted ultracold chemical reactions between Rydberg atoms and polar molecules

Ultracold scattering experiments with Rydberg atoms in dense neutral atom-Rydberg mixtures has led to the discovery of exotic bound long-range Rydberg molecules, with a ground state atom residing within the orbit of a Rydberg electron [2]. We now study the long-range interaction of Rydberg alkali-metal atoms with heteronuclear alkali-metal dimers in the regime of low molecular densities, such that the Rydberg-dimer interaction is dominated by van der Waals forces. We compute accurate C₆ coefficients for a large set of atomic Rydberg states n²L_j interacting with ground state molecules [3]. For the (5²S_1/2)⁸⁷Rb-KRb(J=0) collision pair, we predict large probabilities for forming long-range Rydberg-molecule bound states (trimers) with (n∼50)²D atomic Rydberg character, in a two-photon photoassociation scheme. We discuss the feasibility of detecting Rb-KRb trimers in currently available atom-molecule co-trapping experiments.

[1] J. P. Shaffer et al. Nat. Commun. 9, 1965, (2018).
[2] V. Olaya, J. Pérez-Ríos, F. Herrera, Phys. Rev. A 101, 032705 (2020)