Security Analysis Of Continuous-vairable Quantum Cryptogram Communication Protocols Based On Beam Splitter

As a result of integrating quantum mechanies and information theory，quantum communication is also a hot research topic for the informationseience.During the last30years, quantum communication has been gradually developedfrom theory to experiment, and towards practicality. The essential components ofquantum information transmission system include quantum signal generator, quantumtransmission channels, quantum logical gates, and quantum measurement setups, whichare implemented in the practical physical system for the efficient quantum informationprocessing(QIP) tasks. Because of the signal intensity, high measuring accuracy, highefficiency, continuous-variable quantum communication is becoming a focus in theinformation field, and many important outcomes have been obtained.So far, quantumcommunication is primarily concerned with quantum cryptography communication,quantum teleportation, and quantum superdense coding, etc.With the help of the work model of quantum beam splitter, we have done sometheoretical work which continuous-variable quantum cryptography communication inthe following respects.We investigated the quantum entangling properties of a pair of coherent squeezedstates passing through a single beam splitter. From valuating the degree of entanglementin terms of entanglement of formation, we generate maximally entangled output statefor the same two coherent squeezed states inputting，provided efficient、controllablequantum resources for continuous-variable QKD of quantum security communicationbased on beam splitter.The security against anticlone attacks for quantum secure communication withEinstein-Podolsky-Rosen correlation was discussed. We restricted security analysis inindividual anticlone attacking in the case of eavesdropper controls the quantum channel.The dependence of secret information rate on the parameters of two beam splitters inGaussian cloner is analyzed and the secure bound is given.We investigate the security of a continuous-variable quantum cryptography schemewith four states protocol against beam splitting attack. We restricted security analysis inbeam splitting attacking in the case of eavesdropper controls the quantum channel. Thedependence of additive noise, linear amplifier G and relationship of quantumchannel transmission rate. The postselection process is density resistance amplificationsystem on quantum cryptography, so the results showed that continuous-variablequantum cryptographic scheme with four states protocol can be secure in the presenceof the transmission loss.