Generating a maximally entangled state via a pure global noise environment

We studied the entangling power of two pure global noises, i.e. amplitude damping noise and classic noise. The entangling power of the two-qubit amplitude damping global noise periodically oscillates with time. Additionally, the entangling power of two-qubit global classical noise increases exponentially with time. The maximum entangling power of both of them exceeds that of the perfect entanglers. Based on this, we propose the conditions for generating a maximally entangled state with global noise acting on a two-qubit separable state. Only if the two-qubit composite system, which is initially in one of those product states: 1 2 ( | 0 ? +/- | 1 ? ) circle times 1 2 ( | 0 ? +/- | 1 ? ) , | 10 ? and | 01 ? suffers an amplitude damping global noise, can we prepare this system in the maximally entangled state by appropriately controlling the evolution time of amplitude damping. Finally, we investigate the disentanglement of the maximum entangled Bell state using these two types of global noise. The two global noises cannot completely disentangle the Bell states phi +/- . Under the influence of amplitude damping global noise, the entanglement of Bell state psi + undergoes a cyclical variation, alternating between disappearance and recovery to reach maximum entanglement within one period. The entanglement of either Bell state psi + or psi - is completely independent of global classical noise. The entanglement of Bell state psi - is also robust against amplitude damping global noise.