Coherent Light Shift on Alkaline-Earth Rydberg Atoms from Isolated Core Excitation without Autoionization

New experimental quantum simulation platforms have recently been implemented with divalent atoms trapped in optical tweezer arrays, with promising performance. The second valence electron also brings about new prospects through the so-called isolated core excitation (ICE). However, autoionization presents a strong limitation to this use. In this study, we propose and demonstrate a new approach to applying a sizable light shift to a Rydberg state with close-to-resonant ICE while avoiding autoionization. In particular, we investigate the ICE of ytterbium atoms in S-1(0) Rydberg states. Spectroscopic studies of the induced autoionization and the light shift imparted to the Rydberg states are well accounted for with multichannel quantum defect theory. Such control over the inner electron without disturbing the Rydberg electron brings about a new tool for the targeted coherent manipulation of Rydberg states in quantum simulation or quantum computing experiments performed with alkaline-earth atoms.