Entanglement Transfer Between Two-level Atom And Coupling Cavity In Non-Markovian Environment

Quantum entanglement is one of the most obvious characteristics of quantum mechanics,and it is an important manifestation of the difference between quantum physics and classical physics.The importance of quantum entanglement is clearly reflected in theoretical research and practical applications.First,one can obtain more information about the fundamental theory of quantum mechanics by studying quantum entanglement.Sencond,the application of quantum information theory in practice is inseparable from the role of quantum entanglement.As we all know,it is impossible to find a completely closed system in actual operation,so the external environment will always inevitably disturb the system,which will cause the decoherence of the system and destroy the entanglement of the system.The effect of the environment on the system is the main obstacle in the applications of quantum information.In this case,it is of practical significance to study the entanglement evolution of quantum open systems.There are two types of the dynamic evolution of a quantum system,Markovian and non-Markovian,where the latter one has a memory effect.The information and energy flowing to the environment will react against the system.It is precisely because of this feedback effect that the decoherence phenomenon can be delayed.Based on this,this paper mainly studies the entanglement evolution characteristics of the coupled cavity and two non-interacting two-level atoms,and explores the influence of the non-Markov environment on the entanglement transfer.The theoretical model studied in this paper is composed of two cavities connected by a superconducting quantum interferometer(SQUID)and two two-level atoms embedded in the cavities,which can be simulated by circuit QED.Using the"non-markovian quantum state diffusion(NMQSD)",we derive the mast equation of the system,and analyze the influence of the non-Markovian environment on the entanglement evolution of the system in detail from the following aspects.First,we discuss the entanglement transfer from the cavity fields to the qubits under the rotating-wave approximation.Studies have shown that although the concurrence is gradually decreasing due to the interaction between the system and the environment.the entanglement is still periodically transferred to the atoms.Secondly,we control the transition of the external environment from Markov to non-Markov by changing the length of memory time,and found the longer the memory time,the closer it is to non-Markov environment,the greater the concurrences transferred to the atom,and there will be multiple entanglement death-revival phenomenon occur.On the contrary,when the memory time is shorter,the environment shows the Markov effect.At this time,the maximum value of entanglement is obviously smaller than the former,and the phenomenon of entanglement resurrection will no longer appear after death.Therefore,the non-Markov environment can enhance the entanglement transmission to protect the entanglement.At the same time,the memory effect also significantly enhances the generation of entanglement.Finally,we also studied the influence of the inter-cavity coupling coefficient on the entanglement dynamics of the system,and found that the inter-cavity coupling coefficient can change the amounts and speed of the entanglement transfer,so the entanglement transfer between the systems can be maintained by selecting the optimal coupling coefficient.