Finally, even with the considerations of a single molecule coupled to the single cavity mode under the dipole approximations, we want to emphasize that the accuracy and validity of JC and Rabi models need to be carefully assessed before adapting them to the field of molecular cavity QED. This is because these models only consider two electronic states {|g⟩ , |e⟩} and the transition dipole µ ge (R) between them, where the permanent dipole is often ignored. Unfortunately, these well-established approximations in the atomic cavity QED can explicitly break down for molecular cavity QED systems. A detailed example of the breakdown of these models is provided in Fig. of Sec. 3.1.3.