Optical coherent manipulation of alkaline-earth circular Rydberg states

Owing to their large size, Rydberg atoms are promising tools for quantum technologies 1 , 2 , as they exhibit long-range dipole–dipole interactions and strong coupling to external fields. Recent experiments have demonstrated their appeal for quantum simulation purposes 3 – 5 , even though the relatively short lifetime of optically accessible Rydberg levels imposes limitations. Long-lived circular Rydberg states 6 , 7 may provide a solution. However, the detection of circular states involves either destructive 6 or complex 7 measurement techniques. Moreover, so far, alkali circular states have been manipulated only by microwave fields, which are unable to address individual atoms. The use of circular states of a different group of atoms, the alkaline-earth metals, which have an optically active second valence electron, can circumvent these problems. Here we show how to use the electrostatic coupling between the two valence electrons of strontium to coherently manipulate a circular Rydberg state with optical pulses. We also exploit this coupling to map the state of the Rydberg electron onto that of the ionic core. This experiment opens the way to a state-selective spatially resolved non-destructive detection of circular states and to the realization of a hybrid optical–microwave platform for quantum technology.