Spontaneous emission by two atoms with different resonance frequencies near a metal surface.

Abstract

The interaction between electromagnetic radiation and two two-level atoms with different resonance frequencies near a perfectly conducting metal surface is considered. The atom-atom and atom-surface separations are assumed to be smaller than the corresponding mean resonance wavelength. A quantum-mechanical version of the image method is adopted to study the spontaneous emission by such an atomic pair. Within the framework of this approach, each individual atom and its corresponding image are kinematically correlated, while dynamically they are in effect independent. The total radiation rate of the atomic system is calculated as a function of time for various values of frequency difference. Explicit results are given for several different initial states of the atomic system. Some of them exhibit superradiance, and some initially act as photon-trapping states and eventually are able to undergo radiative decay. Oscillations as a manifestation of beating appear in the time evolution of the radiation rate in all cases of the various initial states, when the frequency difference becomes larger than a critical value given as twice the mean halfwidth of the atomic resonance lines.