内容：

The research focus of quantum secure communication can be summarized into three main aspects: The first is to continue to construct more ingenious and practical communication protocols and improve their security analysis to break the existing transmission limits; the second is to connect theoretical analysis with the actual system, so that the established security analysis theory can be smoothly transitioned to the actual system; the third, continuing to promote the engineering and practical feasibility of quantum communication. The talk is positioned on the above three points and introduces the following innovative results. First of all, I am going to elaborate on a practical protocol, the basis-biased four-six-state protocol which has been experimentally demonstrated via an entanglement source by SPDC. It is theoretically and experimentally confirmed that the protocol can effectively resist the influence of the rotating channel. Thus, the problem of frequent calibration of the measurement frame of the BB84 protocol in free space could be solved. Secondly, a standardized security analysis framework based on the four-six state protocol demonstration experimental system is put forward. It transforms the practical security analysis problem into the operator processing problem. At the same time, it provides the solution model of the actual detector efficiencies during the communication and then embeds the desired detector efficiencies into the operators. In this framework, a principal value-matrix method is used to investigate the practical problems of the full Fock space to improve reliability. The analysis in the talk based on the practical system is the first work extending the security analysis numerical approach proposed by Norbert Lütkenhaus et al. to the practical system and more practical factors can continue to be included in this framework.

人物介绍：

Zhangdong Ye got his bachelor’s degree of science (physics) in 2016 at ECNU, Shanghai and then was sent to Tsinghua University without entrance exams to continue his Ph.D. under Prof. Chunguang Du’s supervision in the Department of Physics. After obtaining his doctoral degree in 2021, he joins a department of the government at Yinzhou, Ningbo.