Crossover from a Molecular Bose-Einstein Condensate to a Degenerate Fermi Gas

We demonstrate a reversible conversion of a ${}^6\mathrm{Li}_2$ molecular Bose-Einstein condensate to a degenerate Fermi gas of atoms by adiabatically crossing a Feshbach resonance. By optical in situ imaging, we observe a smooth change of the cloud size in the crossover regime. On the Feshbach resonance, the ensemble is strongly interacting and the measured cloud size is $75(7)\%$ of the one of a noninteracting zero-temperature Fermi gas. The high condensate fraction of more than $90\%$ and the adiabatic crossover suggest our Fermi gas to be cold enough to form a superfluid.