ABSTRACT
This chapter focuses on the relation between quantum and semiclassical approaches in super-radiance theory. The semiclassical solution can be regarded only as an ingredient of a convenient scheme for calculating quantum mechanical expectation values. Indeed, at the earliest stages, when the electric field and the polarization have not yet risen above the level of quantum fluctuations, the radiative process is not a classical one and would be greatly disturbed by measurements. The chapter presents some statistical characteristics of the linear stage of super-radiance. Super-radiance may be treated as an amplification of the field generated by quantum fluctuations of the polarization. Another aspect of super-radiance evolution is a build up of coherence both of the radiation field and the atomic polarization. Initially tiny, it grows to a macroscopic size and exhibits the statistics of super-radiance pulses. The parameters characterizing the shape of the pulse vary strongly enough within the ensemble for their root mean square deviations.
