Hybrid Continuous-discrete Variable Quantum Key Distribution

As one of the main applications of quantum cryptography, Quantum Key Distribution (QKD) is a promising secure key transmission method. Compared with traditional communication methods, QKD protocols based on the basic principles of quantum mechanics have unconditional security in theory. In general, the preparation and transmission of quantum states during QKD require the encoding, transmission, and measurement of photons. In recent years, QKD has made great progress in theory and engineering applications, and has also promoted the deployment of QKD networks all over the world. This paper focuses on several recent works on hybrid continuous-discrete variable QKD protocols. Combined with the coding method of discrete variable QKD and the detection method of continuous variable QKD, the advantages and disadvantages of building a QKD channel in practice are analyzed. Given the current stage of hybrid continuous-discrete variable QKD, we summarized its potential research priorities and difficulties in the future.