Precision Feshbach spectroscopy of ultracoldCs2

We have observed and located more than 60 magnetic field-induced Feshbach resonances in ultracold collisions of ground-state ${}^{133}\mathrm{Cs}$ atoms. Multiple extremely weak Feshbach resonances associated with $g$-wave molecular states are detected through variations in the radiative collision cross sections. The Feshbach spectroscopy allows us to determine the interactions between ultracold cesium atoms and the molecular energy structure near the dissociation continuum with unprecedented precision. Our work not only represents a very successful collaboration of experimental and theoretical efforts, but also provides essential information for cesium Bose-Einstein condensation, ${\mathrm{Cs}}_2$ molecules, and atomic clock experiments.