Study On The Quantum Correlation And Dense Coding Of Atom And Cavity Coupling System

Quantum information science is a new subject that attracts the most attention now.Quantum entanglement providing the core quantum resources in the calculation and processing of quantum information which the most important characteristic.The difinition of quantum entanglemeng is that a kind of non-localized in the presence of two or more quantum systems,which is different from the classical correlation.Quantum teleportation,quantum dense coding,quantum key distribution and so on are all realized by quantum entanglement.People with deep understanding that quantum entanglement failed to describe all kind of quantum correlation.In 2001 Ollivier and Zurek proposed a quantum description of related physical quantities(called quantum discord)that is the difference between the total correlation and classical correlation is system.There is the entanglement is zero but quantum discord may not be zero when the state is the one of the separation state.thats why,people have a strong interest in the study of quantum discord.In a sense,the research of quantum discord is a potential significance for quantum resource.This paper,we first introduce the history of the development of the quantum information.The typical model of the atom and the cavity coupling system and the basic knowledge of quantum entanglement and the concept of quantum entanglement and the application of quantum entanglement.Followed by a detailed introduction of the quantum correlation of quantum entanglement in addition to outside.Secondly,it introduces the concept of quantum correlation like quantum discored and geometric quantum discord in quantum entanglement and other measurement methods and some recent experimental progress.Again the dynamical evolution of quantum correlations of J-C atoms and two isolated atoms of the system,To realize quantum dense encoding using three J-C model and discussed and analyzed the dynamic evolution on the part of various quantum correlations between J-C atoms and single isolated atoms in the system.The research contents are as follows: three aspects:First:the analysis and detailed discussion part of quantum correlation in the model consisting of a single Jaynes-Cummings(J-C)two level atom and an isolated atom.The evolution properties of quantum discord between two atoms in the system are analyzed by numerical calculation with a method of measuring quantum discord is introduced by Dakic et al.At the same time,the evolution of quantum entanglement is also given.The results showed that by improving in purity of W state and the initial entanglement between the two atoms of the system can improve the quantumdiscord.we also find that non maximally entangled state entanglement of quantum entanglement of formation hasno direct effect.beside the number of photons and the coupling constants between atoms and cavity also play an important role in the evolution of quantum correlation.Second: Studied that the evolution of quantum correlations with the time using double J-C model.The purity of two atoms in the W state and the entanglement of two atoms and the system parameters such as photon number is discussed in detail.Calculation results show that the value of the quantum correlation is affected by the purity of the initial state and the initial entanglement..Especially when the number of photons in the cavity is zero,the amplitude of the geometric quantum discord and quantum entanglement decay into such concussion concussion while The value of quantum discord is zero and atomic number and cavity quantum correlation system has high value for some well.Third:Study on the realization of quantum dense encoding of the three J-C model.The three atoms are in the W state The influence of the initial entanglement degree and coupling constant between three atoms on the capacity of dense coding channel are discussed by detail.The results showed that by changing the entanglement of the initial state,which affects the capacity of dense coding channel Like the above two models,the initial entanglement has a positive effect on quantum correlation and the evolution of the coupling constant is change frequency,high frequency coupling constant becomes large.