Orders-of-magnitude improvement in precision spectroscopy of an inner-shell orbital clock transition in neutral ytterbium

Taiki Ishiyama, Koki Ono, Hokuto Kawase +6

An inner-shell orbital clock transition ${}^1{S}_0\leftrightarrow 4f^{13}5d6s^2(J=2)$ in neutral ytterbium atoms has attracted much attention as a new optical frequency standard a…