Research On Multiple Access Technology And Single-photon Wavelength Conversion In Optical Fiber Quantum Communication Networks

QKD(Quantum Key Distribution) technology with unconditional security is based on the basic principle of quantum mechanics, applying the Heisenberg Uncertainty Principle and Quantum No-Cloning Theorem, and thus becomes a hot topic in the quantum physics and cryptography at home and abroad. After 20 years,s development, QKD has been developed from experiments to a small-scale network with dozens of users and from the metropolitan area network to a more large-scale wide area network, especially to a global scale network. Thus research on multiple access technology in quantum communication network is very necessary. This paper mainly studies the multiple access technology, including multiple access in quantum communication network and single-photo wavelength conversion technology in wavelength division multiple access.First, this paper introduces the research and development status of multi-user quantum communication; expounds the significance of research on multiple access technology and single-photon wavelength conversion in a quantum communication network.Secondly, this paper mainly introduces the basis speculative knowledge of multi-user quantum communication technology, the basic structure of quantum key distribution network is described from two aspects of the function and protocol; and introduces the related speculative knowledge of quantum information, including the quantum bit, several quantum states, the Heisenberg Uncertainty Principle, Quantum No-Cloning Theorem and quantization of the light field; and introduces the preparation and detection technology of single-photon signals; quantum communication protocol based on single-photon signals is also introduced, including the BB84 protocol, the decoy state protocol based on weak coherent light.Third, referring to the multiple access methods in classical communication, this paper studies the feasible multiple access technology in quantum communication network, and constructs the multiple access network models, contrastively analysis the quantum key generation rate, knowing that TDMA QKD can offer a no interference, efficient quantum key distribution services, quantum key distribution based on CDMA canachieve the best performance when code weight w=1; As for the proposed quantum key distribution network based on CDMA, this paper puts forward a LBS(Listen Before Send) algorithm to improve its performance; Finally, aiming at the shortage of TDMA network model, this paper introduces the wavelength parameter and WDM technology, putting forward a hybrid WDM-TDMA multi-user network model with large capacity, analyzing the key generation rate.Fourth, Because of quantum information exchange between subnets leading to network congestion in a quantum communication network, this paper studies single-photon wavelength conversion technology in wavelength division multiple access, proving the possibility of the quantum state shift in Four Wave Mixing(FWM) and Difference Frequency Generation(DFG) process, and the conditions of achieving the complete conversion of single-photon wavelength, which provides a theoretical basis for experimental scheme, at last, this paper further proposes a preliminary experimental scheme on FWM and DFG cascade two single photon wavelength conversion, and analysis it.Finally, concluding the paper and the next research work is prospected.