100 millisecond high-efficiency quantum memory was successfully developed
Professors Pan Jianwei and Bao Xiaohui of the University of Science and Technology of China have successfully developed hundreds of milliseconds of high-efficiency quantum memory using cold atomic ensemble, which has laid a solid foundation for the construction of a long-distance quantum relay system. The results were published on the 31st of May in the international authoritative academic journal Natural Photonics.
Quantum relays can solve the major problem of exponential attenuation of photonic signals in optical fibers. It is one of the important ways to realize ultra-long-distance quantum communication in the future. The basic principle of quantum relay is to use the combination of segmented entanglement distribution and entanglement exchange to expand the communication distance. The core is the quantum storage technology. By caching the photon bits, the entanglement connection efficiency can be greatly improved. In order to meet the actual requirements of the long-distance quantum relay, the quantum memory needs to store the single quantum state for a long time and has high read efficiency.
In recent years, experimental research on quantum storage has progressed rapidly, but so far, no system has been able to meet quantum relay needs in both storage time and efficiency. In 2012, Pan Jianwei, Bao Xiaohui, and others first realized millisecond-class high-efficiency quantum memory, but this storage time is still far from the actual demand for long-distance quantum relays.
In order to further improve storage time, Pan Jianwei's team has developed a number of key experimental techniques such as the three-dimensional optical lattice limiting atomic motion in recent years. This has led to a significant suppression of decoherence caused by atomic motion, and finally achieved a storage life of 0.22 seconds. 76% efficient quantum memory. Compared with the 2012 work, this experimental result has improved storage life by nearly two orders of magnitude.
The reviewers gave high recognition to the importance of this work and praised the experiment as "extraordinary skills." The significance of this experiment is that, for the first time, the storage life and readout efficiency are increased to meet the actual needs of long-distance quantum relays. It has been estimated that this result, combined with technologies such as multi-mode storage and high-efficiency communication band interfaces, can theoretically support implementation of entanglement over 500 km through quantum relays. (Reporter Wu Changfeng correspondent Yang Baoguo)
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