  Networks of nonlinear resonators offer intriguing perspectives as quantum
simulators for non-equilibrium many-body phases of driven-dissipative systems.
Here, we employ photon correlation measurements to study the radiation fields
emitted from a system of two superconducting resonators, coupled nonlinearly by
a superconducting quantum interference device (SQUID). We apply a
parametrically modulated magnetic flux to control the linear photon hopping
rate between the two resonators and its ratio with the cross-Kerr rate. When
increasing the hopping rate, we observe a crossover from an ordered to a
delocalized state of photons. The presented coupling scheme is intrinsically
robust to frequency disorder and may therefore prove useful for realizing
larger-scale resonator arrays.
