In quantum optics, atoms/molecules (modeled as twolevel systems) coupled to a single mode in an optical cavity are a well-studied subject. This study has led to well-known model Hamiltonians, such as the Jaynes-Cummings model and the Tavis-Cummings model. Since these two models are also widely used in recent investigations of polariton chemistry, here we briefly discuss them and the intuitive insights they provide. We consider a single emitter with two electronic states |g⟩ and |e⟩ with the following matter Hamiltonian