  We report the observation of the sign reversal of the magnetic correlation
from antiferromagnetic to ferromagnetic in a dissipative Fermi gas in double
wells, utilizing the dissipation caused by on-site two-body losses in a
controlled manner. We systematically measure dynamics of the nearest-neighbor
spin correlation in an isolated double-well optical lattice, as well as a
crossover from an isolated double-well lattice to a one-dimensional uniform
lattice. In a wide range of lattice configurations over an isolated double-well
lattice, we observe a ferromagnetic spin correlation, which is consistent with
a Dicke type of correlation expected in the long-time limit. This work
demonstrates the control of quantum magnetism in open quantum systems with
dissipation.
