Reconciliation Of Quantum Gaussian Distributed Key Based On Turbo Codes

Quantum key distribution (QKD) is a new discipline of secure communications what is generated by the combination of quantum mechanics and information theory. It employs quantum properties to guarantees the confidentiality of information, it’s security is not based on the complexity of the calculation, but rooted by the basic characteristics of the quantum, using Heisenberg uncertainty principle, quantum no-cloning theorem to protect information, thereby enabling both conveyers to realize unconditional secure communication.At the present, the theory and experiments of QKD and its practical applications have very rapidly developed, and become one of the hot areas in the field of quantum communication. Discrete variables QKD uses single photon as information carrier and continuous variable QKD uses coherent state light field as a carrier. In these two modes, reconciliation is indispensable part that realized the final safety communications in the public authorized channel. So far, the most researchers realize the QKD data correction process by using the channel code based on LDPC. Compared with LDPC codes, Turbo code is a efficient channel code that close to the Shannon limit, it do not need to build a huge check matrix, significant savings in memory usage, and coding rate can be adjusted by Turbo code puncturing.In view of the above advantages of Turbo code, in this text, we propose a coordination program, which is Turbo code-based single-photon and continuous variables QKD. It combined with BB84protocol currently used and the error correction capability of the channel coding; ultimately realize reverses coordination through the principle of iterative decoding of Turbo codes.This paper’s major work as follows:1) The paper made the improvements on Turbo codec in the coordination process. On the encoding side, the paper proposes to use linear convolution to obtain codeword, and its parity information generated is compressed through the puncturing; on the decoder side, using syndrome with decoding to recovery information sequence.2) This paper propose a program that is discrete variables (i.e. single-photon) and continuous variable QKD coordinated based on Turbo codes, analysis its performance and the indicators of this program. The program is focus of the SEC-Protocol for continuous variables and multi-level encoding/decoding multi-channel decoder implementation process, as well as for continuous variables soft-input/soft-output to iterative process level, and ultimately makes the key of the communication completely consistent.3) Finally, by Matlab7.0simulation and the calculation of the reconciliation efficiency, to verify the validity and reliability of this proposed method. In the case of20000continuous variables, quantum signal-to-noise ratio with7dB, reconciliation efficiency reached to78.5%.