Comment on "Electric dipole interaction in quantum optics"

It is shown that both Hamiltonians, one with $-\overrightarrow{\mu }·\overrightarrow{\mathrm{E}}$ and the other with $-\overrightarrow{\mu }·\overrightarrow{\mathrm{A}}$ as interaction energy between an atom and the electromagnetic field, lead to Maxwell's equations. In contrast to the viewpoint in Mandel's paper, $\overrightarrow{\mathrm{E}}$ is considered to be proportional to the canonically conjugate field of the vector potential.