A formulation of quantum electrodynamics is given that applies to atoms in a strong laser field by perturbation theory in a non-relativistic regime. Dipole approximation is assumed. With the current wavelengths, squeezing can be proved to be negligible and then, just the linear term in the Hamiltonian can be retained. The dual Dyson series, here discussed by referring it to the Birkhoff theorem for singularly perturbed linear differential equations, can be applied and a perturbation series… CONTINUE READING