Electromagnetic field in a rectangular cavity: an example of second quantization

We consider the case of electromagnetic field inside a rectangular cavity with conducting walls as form system described by classical mechanics equations. pass these equations through Lagrangian formalism to obtain Hamiltonian formulation. Finally we apply canonical quantization end up quantum theory field. Since electrodynamics can be interpreted one photon system, then above is taken “quantization field” or simply second quantization. Â