  We present an input/output analysis of photon-correlation experiments whereby
a quantum mechanically entangled bi-photon state interacts with a material
sample placed in one arm of a Hong-Ou-Mandel (HOM) apparatus. We show that the
output signal contains detailed information about subsequent entanglement with
the microscopic quantum states in the sample. In particular, we apply the
method to an ensemble of emitters interacting with a common photon mode within
the open-system Dicke Model. Our results indicate considerable dynamical
information concerning spontaneous symmetry breaking can be revealed with such
an experimental system.
