Collective population evolution of two-level atoms based on mean-field theory
Hiroyuki Takeda · Physical Review A · 2012
I theoretically demonstrate the collective population evolution of two-level atoms, based on the mean-field theory. Optical materials with abrupt changes of electromagnetic local densities of states enable steady-state population inversion of two-level atoms which is generally considered impossible. In previous studies, details of the population evolution of a single two-level atom were discussed. However, behaviors of the population evolution of collective two-level atoms are very different from those of a single two-level atom. In this paper, temporal behaviors of the collective population evolution for input electric fields with constant and time-dependent amplitudes are discussed in detail. Moreover, I develop the effective method to calculate the collective spontaneous emission for non-Markovian dynamics. Finally, I discuss the validity of the mean-field theory for a large number of two-level atoms in spontaneous emission using the Markovian approximation.