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Quantum network diagram. The ball represents a quantum node, and the line represents a channel. Different nodes use a channel to transmit photons for connection. Different colored balls represent the various quantum systems that make up the quantum network. The lower right corner illustration shows the energy level structure of quantum dots and solid-state quantum memory.
Prof. Guo Guangcan, a professor at the University of Science and Technology of China, and the Key Laboratory of Quantum Information of the Chinese Academy of Sciences, made new progress in the study of quantum relays and quantum networks. The Li Chuanfeng team of the laboratory successfully achieved the deterministic single photon emission of quantum dots. Multi-mode solid-state quantum storage. This achievement is the first time in the world to realize the docking between two different solid-state systems, quantum dots and solid-state quantum memory, and has realized 100 modes of multi-mode quantum storage. The number of patterns has created the highest level in the world. It is quantum relay and all solid state. The foundation for the realization of quantum networks lays a solid foundation. The research results were published in the Nature News on October 15.
Entanglement distribution is the core technology for building quantum networks. Due to the inevitable transmission loss in the channel, the current direct entanglement distribution in the channel can only reach the order of 100 km. To achieve long-range entanglement distribution, the quantum relay technology based on single-photon quantum storage and two-photon Bell-based measurement is needed. . Quantum storage or quantum relay solutions that have been experimentally verified are based on storage of probabilistic light sources (photon generation probabilities are generally less than 1% and multiphoton subitems exist), and long-range entanglement distribution time for such schemes is expected to be in the order of minutes. the above.
Li Chuanfeng's research group uses self-organizing quantum dots to generate a deterministic single photon source (photon generation probability is 100% and there is only a single photon at a time) and then transmitted over an optical fiber to a solid state on another optical platform 5 meters away. Quantum memory. On the one hand, they use local optical heating methods to adjust the wavelength of single photon to match the operating wavelength of solid-state quantum memory. On the other hand, they use optical frequency comb technology to store single photons to the “sandwich†type solid-state quantum memory [PRL] independently researched and developed by the research group. 108, 190505; PRL 115, 113002], and measured the storage fidelity of the single-photon polarization state of 91.3%. The research group further experimented with 100 patterns of deterministic single-photon multimode quantum storage, and the number of models created the highest level in the world.
The results of the experiment demonstrate two of the most important elements for accelerating the distribution of entanglement, namely deterministic quantum light sources and multi-mode quantum storage. The former can be exponentially accelerated and entangled, while the latter can be linearly accelerated. The combination of the two can be expected to shorten the time for long-distance entanglement distribution to milliseconds. This achievement also realized for the first time two solid-state quantum nodes, namely the connection of quantum dots and solid-state quantum memory, and took an important step towards the realization of an all-solid-state quantum network.
The reviewers gave a high evaluation of the results: "(Connecting) Pure Solid State Quantum Light Sources and Solid State Quantum Memory have made a significant contribution to the field", "This work has taken an important direction in the right direction (quantum relay). One step."
The common first authors of the article are Tang Jianshun (quantum dot) and Zhou Zongquan (solid state storage). This work was funded by the State Fund Committee, the Chinese Academy of Sciences, the Ministry of Science and Technology and the Ministry of Education.
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