Three closely related types of excitonic quasiparticles have been recently studied: polaritons, phonoritons and photoritons. We show that the well known polariton displays frequency‐tunable intrinsic squeezing. Related to this is a new Quantum Optics Extinction Theorem. The phonoriton is associated with a ‘‘reconstruction’’ of the dispersion equation for the parent‐polariton: tests have so far proven elusive. Two new experiments are proposed and analyzed for identifying the phonoriton: Non‐Linear Resonance Brillouin Scattering, and Non‐Linear Reflectivity. Some remarks are made about the photoriton.