Research On The Quantum Information Entropy Of Two-body Entanglement In Quantum Noise Channel

Quantum information science is a frontier subject, which is found more superiorthan the classical information science. It is based on the theoretical foundation ofquantum mechanics and information science, by using the qubits, which is the carrier ofinformation, instead of the classical bits of information and encoding in the quantumstate, the transfer of information will be realized by means of quantum entanglement.In the past over20years, researchers have made a breakthrough in the field ofquantum information science and concluded achievements beyond classicalinformation’s capacity, such as the absolutely secure quantum key, quantum densecoding, quantum teleportation and etc. Quantum communication is an important branchof quantum information, mainly involving quantum teleportation, quantum densecoding, quantum key distribution and etc. So far, many papers in the field of quantumteleportation have been published, most of which use maximally entangled state as thequantum channel, so the probability of the quantum state obtained is equal to1. But inthe case of actual situation, it is difficult for us to obtain ideal channel because of theeffect of decoherence and noise in the channel. It will have universal significance if nonmaximally entangled states are used as the quantum channel in quantum communication,but the probability of the quantum state obtained will be not equal to1. At the sametime, quantum entropy theory has been paid great attention since it is widely used in thefield of quantum physics, especially quantum optics and quantum information sciencein recent years. It is the basis and tool to understand and study hot topics like thequantum computation, quantum communication and so on. Quantum entropy theory is used in this paper to study the changes of entanglementdegree after the quantum teleportation of Bell entangled state in ideal channel and noisechannel. The main contents include five parts: In the first part, GHZ maximallyentangled state is used as ideal quantum channel to accomplish quantum teleportation ofBell entanglement state. In the second part, three-particle non-maximally entangledstate is used as noise quantum channel to accomplish probabilistic quantumteleportation of Bell entanglement state. In the third part, the method of probabilisticquantum teleportation of Bell state is extended to the probabilities quantumteleportation of generalized Bell state. In the fourth part, the quantum informationentropy is used to measure the Bell state in all kinds of quantum teleportation and theprobability of successful quantum teleportation in noise channel is calculated. In the lastpart, the changes of entanglement degree after the quantum teleportation of Bellentangled state in ideal channel and noise channel and the changes of the probability ofquantum teleportation successful with the noise channel parameters are analyzed tofigure out a proper parameter range of quantum channel in non-ideal conditions, thusthe entanglement degree of quantum information state and the comparatively highprobability of successful quantum teleportation are guaranteed. Consequently, resultsconcluded in this paper have certain guiding significance on the selection of quantumchannel.