Monopole-dipole resonant energy transfer between Rydberg atoms and polar molecules 

We observe and describe the resonant energy transfer (RET) process between two equal parity s-states in a helium Rydberg atom, and opposite parity states in ammonia. The observation thus represents a monopole-dipole RET process that necessarily requires spatial overlap of the Rydberg-electron and molecular wavefunctions. Calculations that explicitly account for the charge-dipole interaction between the Rydberg electron and the molecular dipole, quantitatively agree with the experimental observations. Total parity is conserved in the collision through the mixing of collisional angular momentum in the atom-molecule complex. This work opens opportunities to expand the quantum science toolbox in hybrid atom-molecule platforms.