  Optical interferometry has been a long-standing setup for characterization of
quantum states of light. Both the linear and the nonlinear interferences can
provide information about the light statistics an underlying detail of the
light-matter interactions. Here we demonstrate how interferometric detection of
nonlinear spectroscopic signals may be used to improve the measurement accuracy
of matter susceptibilities. Light-matter interactions change the photon
statistics of quantum light, which are encoded in the field correlation
functions. Application is made to the Hong-Ou-Mandel two-photon interferometer
that reveals entanglement-enhanced resolution that can be achieved with
existing optical technology.
