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Recycling nonlocality in a quantum network

Ya-Li Mao, Zheng-Da Li, Anna Steffinlongo, Bixiang Guo, Biyao Liu, Shufeng Xu, Nicolas Gisin, Armin Tavakoli, Jingyun Fan

10/2/22 Published in : arXiv:2202.04840

It has recently been discovered that the nonlocality of an entangled qubit pair can be recycled for several Bell experiments. Here, we go beyond standard Bell scenarios and investigate the recycling of nonlocal resources in a quantum network. We realise a photonic quantum 3-branch star network in which three sources of entangled pairs independently connect three outer parties with a central node. After measuring, each outer party respectively relays their system to an independent secondary measuring party. We experimentally demonstrate that the outer parties can perform unsharp measurements that are strong enough to violate a network Bell inequality with the central party, but weak enough to maintain sufficient entanglement in the network to allow the three secondary parties to do the same. Moreover, the violations are strong enough to exclude any model based on standard projective measurements on the EPR pairs emitted in the network. Our experiment brings together the research program of recycling quantum resources with that of Bell nonlocality in networks.

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  • Quantum Systems

The free field realisation of the BVW string

Exponential Networks, WKB and the Topological String

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