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arXiv:2203.16207 · Physical Review Letters

Entanglement Swapping and Quantum Correlations via Symmetric Joint Measurements

Cen-Xiao Huang, Xiao‐Min Hu, Yu Guo, Chao Zhang, Bi‐Heng Liu, Yun‐Feng Huang, Chuan‐Feng Li, Guang-Can Guo, Nicolas Gisin, Cyril Branciard, Armin Tavakoli

Published Jul 13, 2022• 59 citations
arXivHTMLPDF

Abstract

We use hyperentanglement to experimentally realize deterministic entanglement swapping based on quantum elegant joint measurements. These are joint projections of two qubits onto highly symmetric, isoentangled bases. We report measurement fidelities no smaller than 97.4%. We showcase the applications of these measurements by using the entanglement swapping procedure to demonstrate quantum correlations in the form of proof-of-principle violations of both bilocal Bell inequalities and more stringent correlation criteria corresponding to full network nonlocality. Our results are a foray into entangled measurements and nonlocality beyond the paradigmatic Bell state measurement and they show the relevance of more general measurements in entanglement swapping scenarios.

DOI
10.1103/physrevlett.129.030502

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Entanglement swapping is a process by which two initially independent quantum systems can become entangled and generate nonlocal correlations. To characterize such correlations, we compare them to those predicted by bilocal models, where systems that are initially independent are described by uncorrelated states. We extend in this paper the analysis of bilocal correlations initiated in [Phys. Rev. Lett. 104, 170401 (2010)]. In particular, we derive new Bell-type inequalities based on the bilocality assumption in different scenarios, we study their possible quantum violations, and we analyze their resistance to experimental imperfections. The bilocality assumption, being stronger than Bell's standard local causality assumption, lowers the requirements for the demonstration of quantumness in entanglement-swapping experiments.
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