Entanglement Dynamics and its Application for Two Qubits in Dissipative Environment

An entanglement dynamics of two dissipative qubits under different situation of initial conditions is studied. We find that the periodic disentanglement and entanglement results from the interaction between two qubits, while the disentanglement is primarily caused by environmental perturbations. In the two cases of a pure dephasing environment and a normal environment, the sudden death of entanglement (ESD) is happened. For a simple dissipative environment, the sudden death of entanglement disappears for non-interacting qubits. The concurrence decreases gradually with the involving time, where the stronger the strength interacting with the environment is, the faster the attenuation of the amplitude of concurrence should be. Without the interaction with the environment, ESD would disappear. Furthermore, the applications of quantum entanglement are discussed in the rotating operator dynamics and the populations of quantum states.