Peculiarities of the interaction-induced modifications of the decay of different Zeeman sublevels of an atom excited in isotropic environment

On the basis of a consistent quantum microscopic approach, we consider the decay of a multilevel atom excited in an ensemble of resonant two-level atoms. We show that the decay rate of different Zeeman sublevels of the excited state can be different, unlike in the case of a free atom. This effect is observed even when the environment is isotropic. Furthermore, we find that different irreducible components of the density matrix of initially excited multilevel atoms also differ in terms of decay rate.