Comment on "Maxwell's equations in the multipolar representation"

It is shown that Haller's interpretation of the unitary transformation from the minimalcoupling to the multipolar form of the Hamiltonian in nonrelativistic quantum electrodynamics not only conflicts with the Maxwell-Lorentz equations but also ascribes a special status to the minimal-coupling Hamiltonian which is not warranted by the general method of canonical quantization. The correct interpretation of the transformation as the quantum analog of a classical canonical transformation is reiterated. It is also shown that the transformation is equivalent to a gauge transformation of the electromagnetic potentials.