Superradiance Startup at Finite Temperatures of the Electromagnetic   Field
  We use quantum-electrodynamical approach to study the initial stage of Dicke superradiance from a system of two-level atoms. Applying the zeroth-order Magnus approximation, we obtain the expression for the mean number of quanta emitted in the presence of thermal fluctuations of the electromagnetic field. 
S.V. Anishchenko
physics.optics quant-ph