The effect of dipole-dipole interaction for two atoms with different   couplings in non-Markovian environment
  Using the nonperturbative method, we study the exact entanglement dynamics of two two-level dipole-dipole interacting atoms coupled to a common non-Markovian reservoir with different coupling strengths. Besides analyzing the conditions for the existence of steady state, we find, though the dipole-dipole interaction could destroy the stationary entanglement, that relatively strong dipole-dipole interaction does suppress the disentanglement in the initial period of time. These results are helpful for the practical engineering of the entanglement in the future. 
Yang Li, Jiang Zhou, and Hong Guo