Entanglement Dynamics Of Jaynes-Cummings Atoms

Quantum entanglement,as an important physical resource in quantum com-putation and quantum information processing, is one basic feature distinguishing the quantum world from the classical world.Quantum entanglement has more extensive applications in quantum information processing.By means of quantum entanglement one can achieve some tasks which cannot be realized via classical methods,such as quantum teleportation, quantum dense coding and quantum cryptography and so on.However, quantum system is inevitably affected by en-vironment in practice so that the system is disentangled.Recently,the results of study show that entanglement sudden death(ESD) may appear in the process of systematic evolution in theory and experiment.In our paper,entanglement evolution of two independent Jaynes-Cummings atoms without rotating-wave approximation(RWA) is studied by an numerically exact approach and is discussed simultaneously.We examine entanglement dynamics between two non-interacting JC atoms by means of concurrence. The results show that for the initial Bell state with anti-correlated spins, the entanglement sudden death (ESD) is absent in the RWA, but does appear in the present numerical calculation without RWA. Aperiodic entanglement evolution in the strong coupling regime is observed. The strong atom-cavity coupling facilitates the ESD.The sign of detuning play a essential role in the entanglement evolution for strong coupling, which is irrelevant in the RWA. An analytical results based on an unitary transformation are also given, which could not modify the RWA picture essentially. It is suggested that the activation of the photons may be the origin of the ESD. The present theoretical results could be applied to artificial atoms realized in recent experiments.