Avoiding the decay of entanglement for coupling two-qubit system interacting with a non-Markov environment

The entanglement evolution of the coupled qubits interacting with a non-Markov environment is investigated in terms of concurrence. The results show that the entanglement of the quantum systems depends not only on the initial state of the system but also on the coupling between the qubit and the environment. For the initial state (vertical bar 00 > +/- vertical bar 11 >) / root 2, the coupled qubits will always been in the maximum entangled state under an asymmetric coupling. For the initial state (vertical bar 01 > +/- vertical bar 10 >) / root 2, in contrast, the entangling degree of the coupled qubits is always equal to unity and does not depend on the evolving time under the symmetric coupling. We find that the stronger the interaction between the qubits is, the better the struggle against the entanglement sudden death is.