  We investigate the steady states of a lossy array of nonlinear optical
resonators that are driven by lasers and interact via mutual photon tunneling.
For weak nonlinearities, we find two-mode squeezing of polaritons in modes
whose quasi-momenta match the relative phases of the laser drives. For strong
nonlinearities the spatial polariton density-density correlations indicate that
the polaritons crystallize and are predominantly found at a specific distance
from each other despite being injected by a coherent light source and damped by
the environment.
