Two qubit entanglement preservation through the addition of qubits

An entanglement preservation scheme is proposed by considering the exact evolution of an NN-qubit interacting system in a common reservoir. We find that the steady-state concurrence is dependent only on the number of qubits, the qubit–reservoir coupling strength and the initial conditions of the system. Furthermore, we show that as N→∞N→∞, the initial entanglement between the two qubits is preserved.