Experimental Demonstration that No Tripartite-Nonlocal Causal Theory Explains Nature's Correlations

Abstract

Quantum theory predicts the existence of genuinely tripartite-entangled states, which cannot be obtained from local operations over any bipartite entangled states and unlimited shared randomness. Some of us recently proved that this feature is a fundamental signature of quantum theory. The state $|{GHZ}_3⟩=(|000⟩+|111⟩)/\sqrt{2}$ gives rise to tripartite quantum correlations which cannot be explained by any causal theory limited to bipartite nonclassical common causes of any kind (generalising entanglement) assisted with unlimited shared randomness. Hence, any conceivable physical theory which would reproduce quantum predictions will necessarily include genuinely tripartite resources. In this work, we verify that such tripartite correlations are experimentally achievable. We derive a new device-independent witness capable of falsifying causal theories wherein nonclassical resources are merely bipartite. Using a high-performance photonic $|{GHZ}_3⟩$ states with fidelities of $0.9741\pm 0.002$, we provide a clear experimental violation of that witness by more than $26.3$ standard deviation, under the locality and fair sampling assumption. We generalise our work to the $|{GHZ}_4⟩$ state, obtaining correlations which cannot be explained by any causal theory limited to tripartite nonclassical common causes assisted with unlimited shared randomness.

See related work by Ya-Li Mao et al. (arXiv:2201.12753). 12 pages (7 of appendices), 5 figures (2 in appendices). H.C., M-O.R. and C.Z contributed equally to this work

References in corpus (8)

• Beyond Bell's Theorem: Correlation Scenarios
• Bell nonlocality in networks
• Direct generation of three-photon polarization entanglement
• A no-go theorem on the nature of the gravitational field beyond quantum theory
• Test of Genuine Multipartite Nonlocality
• Any Physical Theory of Nature Must Be Boundlessly Multipartite Nonlocal
• Non-Local Boxes for Networks
• Covariance Decomposition as a Universal Limit on Correlations in Networks

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• Probing many-body Bell correlation depth with superconducting qubits
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• General spin systems without genuinely multipartite nonlocality
• Guarantees on the structure of experimental quantum networks
• Testing the necessity of complex numbers in traditional quantum theory with quantum computers
• Experimental genuine quantum nonlocality in the triangle network
• Testing Genuine Multipartite Nonlocality via an Inflated Network with Multi-copy Entangled States
• Consistency and Causality of Interconnected Nonsignaling Resources
• Strength of statistical evidence for genuine tripartite nonlocality