Antiferromagnetic Interorbital Spin-Exchange Interaction of ${}^{171}$Yb

We report on the investigation of the scattering properties between the ground state ${}^1{S}_0$ and the metastable state ${}^3{P}_0$ of the fermionic isotope of ${}^{171}$Yb. We successfully measure the $s$-wave scattering lengths in the two-orbital collision channels as $a_{eg}^{+}=225(13)a_0$ and $a_{eg}^{-}=355(6)a_0$, using the clock transition spectroscopy in a three-dimensional optical lattice. The result shows that the interorbital spin-exchange interaction is antiferromagnetic, indicating that ${}^{171}$Yb atom is a promising isotope for the quantum simulation of the Kondo effect with the two-orbital system.