The Research Of Data Reconciliation Frame In Continuous Variable Quantum Key Distribution System

Cryptography is one of important tools to guarantee information security.Quantum cryptography based on quantum mechanics can provide unconditionalsecure communication, the core part of which is quantum key distribution (QKD).The continuous variable QKD system has been one of the hotspots in quantum keycommunication, because which overcomes the faults such as weak signals, easyattenuation, low detection efficiency and so on in the discrete variable QKD systemwith single photons for information carrier.Quantum key distribution contains key transference and data reconciliation. Datareconciliation is the process of data error correction on the public classical channelafter the receiver has obtained the classical data by measuring quantum states. Datareconciliation algorithms based on discrete variables include protocol binary, cascade,side information reconciliation of error correction codes, etc. While the original key inthe continuous variable QKD are Q-ary continuous variables, the above algorithmsbased on discrete variables can not be applied in quantum key for continuousvariables.The paper aims at realizing data reconciliation for continuous variable QKDsystem. First, the theory framework of the multidimensional data reconciliation isanalyzed including the construction and reconstruction of side information. Then thedecoding principle of LDPC and its application superiority are described exhaustively.The multidimensional data reconciliation combined with LDPC with its concreteapplication is put forward for continuous variable QKD, which combines spaceanalytic geometry with the performance of LDPC error correction to realize the dataerror correction. The algorithm is simulated by computers. By adjusting the SNR(Signal Noise Ratio), the relation between the SNR and BER (Bit Error Rate) isthat.BER tend to0when SNR is greater than5.2dB.During the actual communication, the SNR is often less than5.2dB. If the onlyerror correction step taken on the classical channel, it may not reach the requirementsof data reconciliation for BER. Hence, it can be considered that the preliminary data reconciliation is taken on the quantum channel. In other words, the technologies ofquantum error correction codes are introduced to overcome the quantum noise, whichcan improve SNR. The application research of quantum error correction codes forcontinuous variable QKD is still in primary level, about which there are manyproblems to research deeply. Stabilizer codes are one class of the most importantquantum error correction codes. The paper analyzes the basic principles of stabilizercodes, focusing on how to construct stabilizers to achieve the continuous variablequantum error correction in the reconciliation of continuous variable QKD. And anew algorithm called region elimination algorithm for finding the check matrix ofstabilizer codes was presented. The algorithm is also simulated by computers.Finally, both communication terminals (the sender and the receiver) aredeveloped by Visual C++6.0in the platform of Windows, which is used forsimulation of continuous variable quantum key communication. Themultidimensional data reconciliation based LDPC is used in data reconciliation stepfor error correction.