The Study On Features Of Quantum Communication In Non-markovian Environment

Recently, with the development of quantum mechanics and information technology,the actual system of quantum communication becomes a hot researching issue. In thequantum information processing, quantum correlation is considered to be a veryimportant physical resource in quantum communication, quantum computation,quantum dense coding, which plays an important role in the implementation of thequantum information process. However, in the actual environment, quantum systeminevitably interacts with its surrounding environment which results in the reductionassociated characteristics of quantum systems and the physical implementation ofquantum information processing tasks. Therefore, the open quantum system has becomea very important subject. In this thesis, the relationship between the environmental noiseand the fidelity of quantum communication were mainly discussed in thenon-Markovian process of quantumcommunication. the main content is as follows:In the introduction chapter, the recent studies about quantum communication havebeen reviewed. Then the backgrounds and significance of quantum communication innon-Markovian environment is introduced.In addition, a brief study of the contents,innovation and structural arrangements of this thesis has been introduced.In chapter2, the basic knowledge of single qubitquantum teleportation and remotestate preparation(RSP) base on tow-level atom system have been firstly reviewed. Thequantum entanglement and quantum discord have been introduced in detail and theresearch method and characterization tools involved in this paper has been described.In chapter3, the influence of the atomic dipole-dipole interaction intensity on theentanglement dynamics of the system has been discussed. The results show that themagnitude and the period of entanglement depend on the atomic dipole-dipoleinteraction. When ignoring the dipole-dipole interaction between atoms, the system haspresented periodic entanglement dynamics behavior, indicating that the cooperativeeffect between atoms effectively restrained excited state energy attenuation. However,when considering the dipole-dipole interaction between atoms, the oscillation frequencybetween the two entangled atoms has decreased, and the concurrence of diatomicsystems fails to decay to zero. So, the dipole-dipole interaction played in strengtheningof double atomic excited state energy decay.In chapter4, this chapter mainly discusses the single qubitquantum teleportation ofquantum state in the open quantum systems and calculates the fidelity of quantumcommunication under Markovian and non-Markovian environment. The study found theaverage fidelities of teleportation isdecreasing exponentially over time in Markovianenvironmentand attenuating oscillatorily in non-Markovian. The quantumsystemsformed by different basis have the different sensibilityof Markovian and non-Markovianeffects.In chapter5, a study was carried out to investigate the dynamic properties ofQuantum Discord as quantum resources under the Markovian noise environment. Though analyzing and calculating for the X-state, the study found that under thenon-Markovian environment, frequency detuning amount between the field and atomiccenter could make the fidelity of quantum communication to maintain at a high level,which provides effective method to improve the fidelity of quantum communication innoise environment.As the detuning growing. even thelower purity of initialentanglement, the fidelity can be preservedat comparative high levels, effectively.