  There exists a growing interest in the properties of the light generated by
hybrid systems involving a mesoscopic number of emitters as a means of
providing macroscopic quantum light sources. In this work, the quantum
correlations of the light emitted by a collection of emitters coupled to a
generic optical cavity are studied theoretically using an effective Hamiltonian
approach. Starting from the single-emitter level, we analyse the persistence of
photon antibunching as the ensemble size increases. Not only is the photon
blockade effect identifiable, but photon antibunching originated from
destructive interference processes (the so-called unconventional antibunching)
is also present. We study the dependence of these two types of negative
correlations on the spectral detuning between cavity and emitters, as well as
its evolution as the time delay between photon detections increases. Throughout
this work, the performance of plasmonic nanocavities and dielectric
microcavities is compared: despite the distinct energy scales and the
differences introduced by their respectively open and closed character, the
bunching and antibunching phenomenology presents remarkable similarities in
both types of cavities.
