Non-Markovian decoherence dynamics of entangled coherent states

We microscopically model the decoherence dynamics of entangled coherent states of two optical modes under the influence of vacuum fluctuation. We derive an exact master equation with time-dependent coefficients reflecting the memory effect of the environment, by using the Feynman-Vernon influence functional theory in the coherent-state representation. Under the Markovian approximation, our master equation recovers the widely used Lindblad equation in quantum optics. We then investigate the nonMarkovian entanglement dynamics of the two-mode entangled coherent states under vacuum fluctuation. Compared with the results in Markovian limit, it shows that the non-Markovian effect enhances the disentanglement to the initially entangled coherent state. Our analysis also shows that the decoherence behaviors of the entangled coherent states depend on the symmetrical properties of the entangled coherent states as well as the couplings between the optical fields and the environment.