Observation of an Orbital Interaction-Induced Feshbach Resonance in 173Yb

We report on the experimental observation of a novel interorbital Feshbach resonance in ultracold ¹⁷³Yb atoms. This opens up the possibility of tuning the interactions between the ¹S₀ and ³P₀ metastable state, both possessing zero total electronic angular momentum. The resonance is observed at experimentally accessible magnetic field strengths and occurs universally for all hyperfine state combinations. We characterize the resonance in the bulk via interorbital cross thermalization as well as in a three-dimensional lattice using high-resolution clock-line spectroscopy. Our measurements are well described by a generalized two-channel model of the orbital-exchange interactions.