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

Huan Cao, Marc-Olivier Renou, Chao Zhang, Gaël Massé, Xavier Coiteux-Roy, Bi-Heng Liu, Yun-Feng Huang, Chuan-Feng Li, Guang-Can Guo, Elie Wolfe
2022 arXiv   pre-print
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⟩)/√(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
more » ... ent) 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±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.
arXiv:2201.12754v2 fatcat:o427eio6ffakzkwzvzio3dfmia