  We report on the experimental observation of a strongly interacting gas of
ultracold two-electron fermions with orbital degree of freedom and magnetically
tunable interactions. This realization has been enabled by the demonstration of
a novel kind of Feshbach resonance occurring in the scattering of two 173Yb
atoms in different nuclear and electronic states. The strongly interacting
regime at resonance is evidenced by the observation of anisotropic hydrodynamic
expansion of the two-orbital Fermi gas. These results pave the way towards the
realization of new quantum states of matter with strongly correlated fermions
with orbital degree of freedom.
