Controlled entanglement of two atoms in photonic crystals

The exact entanglement dynamics of two dipole–dipole interacting two-level atoms coupled to a common photonic band-gap (PBG) environment has been investigated. We show that the detuning conditions and the dipole–dipole interaction (DDI) are two essential ingredients and their interplay plays a crucial role in controlling the entanglement of the two-qubit system. For the negative detuning, corresponding to the case where the atomic transition frequency is inside the band gap, the entanglement of the two-qubit system can survive in the long-time limit. For the positive detuning, although the fast disentanglement presents, the DDI effects can be used to fight against the deterioration of the entanglement. The theoretical results could be applied to the implementation of quantum information processing in nanostructured materials.