Performance Research Of Quantum Asymmetric Code For Amplitude Or Phase Attenuation Channel

Quantum information is a new emerging cross-disciplinary fusion combining quantum mechanics and information science, can break through the physical limits of existing information technology, which is a very important new generation of technology after Moore Era. Quantum information includes two pieces of content:quantum computing and quantum communication. In the process of quantum communication, quantum coding based on quantum entanglement plays an important role, and in quantum computer quantum error correction is the important guarantee to realize quantum computing and quantum communication.Both quantum computing and quantum communication, quantum coherence is the essence. Unfortunately, quantum coherence is difficult to maintain in the actual system.In quantum computer, qubit is not an isolated system, it will interact with the external environment, resulting in the attenuation of quantum coherence, i.e. decoherence. Therefore, to make quantum computing a reality, a core issue is to overcome decoherence, and so far Quantum encoding is the most effective method to overcome decoherence. In quantum cryptography system, any eavesdropping on the behavior of the photon flow will change the photon state, which the sender or receiver will perceive, so can achieve completely secret communication. The main types of quantum coding scheme are:quantum error-correcting code, quantum error-avoiding code and error-proofing code. Quantum stabilizer code is the most important quantum error-correcting code, and on this basis construct many practical codes, quantum asymmetric code is one of them. We all hope that we construct the system can completely avoid the noise, however, noise is almost inevitable, we can only think of a way to minimize it. In quantum information processing, as in classical information processing using the classical error correction code to protect information, we use the quantum error-correcting codes to protect the quantum information. They have the same basic idea, is to introduce redundancy in the original information to protect the information. Fidelity is a important index to measure the quality of quantum error correcting code.This paper is divided into two parts, the first part mainly introduces the basis of the previous studies, putting coding, noise, decoding to a equivalent channel, computational quantum non symmetric code [4,1] and [6,2] code, and Compute the fidelities of quantum asymmetric [4,1] code and [6,2] code in quantum amplitude attenuation channel, quantum phase attenuation channel and quantum amplitude and phase simultaneous attenuation of the channel. Second piece mainly analyses the reason of [2(M+1), M] code can not be used in quantum phase attenuation channel.