Influence of Non-Linear Interactions on the Propagation of Electromagnetic Fields in Moving Many-Electron Atomic Systems*

Reduced-density-matrix descriptions are developed for the propagation of electromagnetic fields in moving many-electron atomic systems, taking into account the center-of-mass motions, atomic collision processes, and applied magnetic fields. The time-domain (equation-of-motion) and the frequency-domain (resolvent- operator) formulations are developed in a unified manner. A semiclassical perturbative treatment of the electromagnetic interaction is employed to derive compact Liouville- space operator expressions for the general n'th-order non-linear macroscopic electromagnetic-response tensors. Coherent atomic excitations and the full tetradic- matrix form of the collision-radiative self-energy operator in the Markov approximation are taken into account.