The density-matrix approach to cavity radiation and population point process models

The problem of cavity radiation and its detection is reviewed and in particular the evolution equation of Scully and Lamb is studied with special reference to coarse-graining. It is shown that the resulting evolution equation corresponds to that of a Markov process representing the cavity population. The approximations corresponding to oscillations below and above threshold reduce the process to a branching process with immigration. The effect of the detector is also studied and the photocount statistics are shown to correspond to those of an emigration process superposed on the branching process. The identification of the evolution as a branching process is shown to result in considerable simplicity and ease in the determination of the statistical characteristics of the cavity population. In particular the Shepherd model is identified as a special case; a complex situation like the multi-mode oscillation is also identified and the corresponding statistical characteristics obtained. © 1987 Taylor & Francis Ltd.