Important Progress in Quantum Network 7-Kilometer Non-Local Quantum Gate Realized in Hefei
TapTechNews October 6th news, according to the official news of the University of Science and Technology of China, recently, the team of Academician Guo Guangcan of the University of Science and Technology of China has made important progress in the field of quantum networks. Li Chuanfeng, Zhou Zongquan, Liu Biheng and others in the team realized a non-local quantum gate across 7 kilometers in Hefei urban area based on the multi-mode solid-state quantum storage and the quantum gate teleportation protocol, and demonstrated the distributed Deutsch-Jozsa algorithm and the quantum phase estimation algorithm. This result was published in the international journal Nature Communications on October 2nd.
TapTechNews learned from the University of Science and Technology of China that distributed quantum computing is a feasible way to solve the scalability problem of quantum computing. It connects independent quantum computing nodes through non-local quantum gates, thereby integrating the computing power resources in the quantum network to achieve the improvement of the quantum computing scale. However, the non-local quantum gate has only been experimentally demonstrated on a scale of only dozens of meters so far, which cannot meet the need to integrate computing power resources in a large-scale quantum network.
In this work, the research team based on the quantum gate teleportation protocol to establish a non-local quantum gate between two quantum nodes. The straight-line distance between the two quantum nodes is 7 kilometers, which are located on the east campus of the University of Science and Technology of China (referred to as USTC) and on the east side of Dashu Mountain in Hefei (referred to as Dashu Mountain). The research team first carried out the remote distribution of the quantum entangled state between the two nodes using communication band photons and dedicated optical cables. Subsequently, the USTC node and the Dashu Mountain node respectively performed local two-qubit quantum gate operations. The USTC node used europium-doped yttrium silicate crystal to realize the storage of entangled photons until it received the measurement result of the Dashu Mountain node and performed the corresponding single-qubit gate operation according to this result.
Experimental results show that the two-qubit non-local quantum gate operation was completed between the photon of the USTC node and the photon of the Dashu Mountain node, and the fidelity of the controlled NOT gate reached 88.7%. The entanglement storage time of the solid-state quantum memory reached 80.3 μs, which was nearly 2 times higher than that of the previous work, and the number of time modes of entanglement storage reached 1097, which led to a linear improvement in the generation rate of non-local quantum gates. Based on the non-local quantum gate, the research team further demonstrated the two-qubit Deutsch-Jozsa algorithm and the quantum phase estimation algorithm between these two remote nodes, successfully realizing the remote distributed execution of the quantum algorithm.
This work realizes the demonstration of distributed optical quantum computing at the urban distance for the first time, showing t he feasibility of building a distributed quantum computing network based on quantum storage and communication optical cables, and providing a new idea for the realization of large-scale quantum computing.
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