ABSTRACT
This chapter discusses the two sources: the free-electron laser and the electron-hole plasma in semiconductors. It also discusses the atomic nuclei that may super-radiate in the gamma-ray domain may at least in principle be another non-conventional source of super-radiance. The chapter describes an interesting new experiment of De Voe and Brewer, who have directly observed for the first time the effect of two-atom collective emission, just as predicted by R. H. Dicke in 1954 when the whole subject of super-radiance was launched. It then describes the super-radiance effects in synchrotron radiation. The chapter outlines the quantum approach to the problem of free-electron laser. The gamma-ray device is expected to work on a recoilless Mossbauer transition from an excited level pumped from a pure sample of a long-lived isomer. The chapter explains another system that has a continuous energy spectrum and which is a possible source of super-radiance. It is the electron-hole plasma in semiconductors.
