  We consider a laser-driven and dissipative system of two coupled cavities
with Jaynes-Cummings nonlinearity. In particular, we investigate both
incoherent and coherent laser driving, corresponding to different experimental
situations. We employ Arnoldi time evolution as a numerical tool to solve
exactly the many-body master equation describing the non-equilibrium quantum
system. We evaluate the fluorescence spectrum and the spectrum of the
second-order correlation function of the emitted light field. Finally, we
relate the measured spectra of the dissipative quantum system to excitations of
the corresponding non-dissipative quantum system. Our results demonstrate how
to interpret spectra obtained from dissipative quantum systems and specify what
information is contained therein.
