Quantum Information Transmission Via Bit-flip Noisy Channel

In the high-speed development of the information age, nothing can take place of information for its profound influence to the human beings. Now people are more dependent on information. More requirements about high speed, large quantity, security, and accuracy of processing information are also put forward.Under the constant pursuit by people, the classical information technology has got a big development by a surprising speed. But in the end of last century, the progress of classical information met its bottleneck. With the help of quantum mechanics, quantum information is set up, which is superior to classical information in many aspects. Parallel computing can be accomplished by the superposition principle of quantum mechanics, then the quantity of the transmitting information will be promoted. On the other hand, quantum uncertainty principle can guarantee the security of the information processing. How to transmit information accurately via noisy channel is the core issue of my thesis.First, the development of quantum information is introduced briefly. Secondly, some related basic knowledge is given: qubit and its transformation, pure state, mixed state, density operator,optical elements, and the noisy environment. Thirdly, the quantum error-correction code, the quantum error-rejection code, and the quantum error-tolerance code of information transmission via bit-flip noisy channel are discussed. The quantum error-correction code encodes or decodes information by using the controlled-Not gates, which are difficult to realize by optical technology.The quantum error-rejection code decreases the number of the controlled-Not gate, but its efficiency is decreased because some error qubits are abandoned without correction. The error-tolerance code not only avoids the complexity of encoding or decoding, but also increases the efficiency of information transmission, which can be achieved with 100% in theory.Finally, the summary and prospect are given.