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arXiv · 2202.13386

Quantum-Memory-Enhanced Preparation of Nonlocal Graph States

Sheng Zhang·Yu-Kai Wu·Chang Li·Nan Jiang·Yun-Fei Pu·Lu-Ming Duan
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Abstract

Graph states are an important class of multipartite entangled states. Previous experimental generation of graph states and in particular the Greenberger-Horne-Zeilinger (GHZ) states in linear optics quantum information schemes is subjected to an exponential decay in efficiency versus the system size, which limits its large-scale applications in quantum networks. Here we demonstrate an efficient scheme to prepare graph states with only a polynomial overhead using long-lived atomic quantum memories. We generate atom-photon entangled states in two atomic ensembles asynchronously, retrieve the stored atomic excitations only when both sides succeed, and further project them into a four-photon GHZ state. We measure the fidelity of this GHZ state and further demonstrate its applications in the violation of Bell-type inequalities and in quantum cryptography. Our work demonstrates the prospect of efficient generation of multipartite entangled states in large-scale distributed systems with applications in quantum information processing and metrology.

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Sheng Zhang, Yu-Kai Wu, Chang Li, Nan Jiang, Yun-Fei Pu, Lu-Ming Duan. 2022-02-27. Quantum-Memory-Enhanced Preparation of Nonlocal Graph States. https://doi.org/10.1103/physrevlett.128.080501

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