Electromagnetic fields of moving multipoles

Abstract

The theory of the quantized electromagnetic fields is used to find the fields arising from multipoles moving in prescribed trajectories. The currents which are the sources are partitioned into polarization and magnetization currents. Unlike for the case of a fixed electric multipole, there is a magnetization-type current which is a generalization of the well-known Röntgen current for a moving electric dipole. The vector potentials for moving electric and magnetic dipoles and electric quadrupoles are found within the Coulomb gauge and compared with those obtained within the Lorentz gauge. These potentials are used to find the electric and magnetic fields for the three cases. These new results are shown to reduce to the well-known fields for fixed sources.