Incoherent excitation of few-level multiatom ensembles

We investigate the collective interaction of a multi-atom three-level ladder system with an environmental incoherent reservoir. The exact solution of the master equation that describes such a system of atoms emitting distinguishable or indistinguishable photons on interaction with an incoherent reservoir is obtained. The quantum decay interference effects have no influences over steady-state distribution of population among the energy levels. However, the photon statistics of the collectively emitted photons are different in this case. In particular, the normalized second-order photon correlation function shows a minimum in its value for the photons generated on lower atomic transition in a system with orthogonal dipoles. The minimum is due to the steady-state amplified spontaneous emission by the incoherent applied fields.