Quantum relay can solve the major problem of exponential attenuation of photon signals in optical fibers and is one of the important ways to achieve ultra-long-distance quantum communication in the future. The core of quantum relay is quantum storage technology. In recent years,

　　Quantum relay can solve the major problem of exponential attenuation of photon signals in optical fibers, and is one of the important ways to realize ultra-long-distance quantum communication in the future. The core of quantum relay is quantum storage technology . In recent years, experimental research on quantum storage has made great progress, and the storage indicators of many physical systems are constantly improving. Recently, CNMO learned that the team of Academician Guo Guangcan of the University of Science and Technology of China has made new progress in the long-term space multi-mode quantum state storage direction. The research team used magnetic field manipulation technology combined with clock state preparation method to realize long-term storage of photon high-dimensional orbital angular momentum based on cold atom ensemble.

　It is understood that because cold atom ensemble has collective enhancement effect and spectral consistency, it can effectively store the quantum states of photons, and is therefore highly favored as a highly potential quantum memory medium. Numerous work in the academic community shows that layout of multimode memory into the quantum network can greatly increase the channel capacity . Therefore, the implementation of multimode quantum memory is of great value for building high-capacity quantum networks. Although important progress has been made in the field of multimodulus quantum storage, there are still many scientific problems that need to be solved in long-term space multimodulus storage based on cold atom ensemble. One of them is that it is difficult to ensure that the stored multi-module quantum state still has high fidelity after long-term storage.

Experimental Principles

　　In the research process, the scientific research team used the rubidium cold atom system to carry out long-term storage research on high-dimensional multimode photonic states based on the angular momentum degree of freedom of photon orbits, realizing the filtering and detection of single-photon magnitude signal light. In general, this important research result is of great reference significance for the construction of high-capacity quantum networks.