Protecting bipartite entanglement by collective decay and quantum interferences

We study the entanglement dynamics of a pair of identical three-level V-type atoms that are interacting with a common vacuum reservoir. The effect of vacuum-induced coherence in the spontaneous emission of atoms is included in the atomic dynamics. By considering qubits formed from each atom, the entanglement dynamics of the two-qubit system is studied using concurrence as the entanglement measure. We analytically calculate the time evolution of the concurrence for initial entangled states and show that the entanglement among qubits can be preserved in the longtime limit due to vacuum-induced coherence. We demonstrate that the combined effects of vacuum-induced coherence and collective decay of atoms in the common reservoir can protect the entanglement to a better extent in comparison with the case of atoms radiating independently.