We present the first experimental confirmation of the quantum-mechanical prediction of stronger-than-binary correlations. These are correlations that cannot be explained under the assumption that the occurrence of a particular outcome of an n≥3-outcome measurement is due to a two-step process in which, in the first step, some classical mechanism precludes n−2 of the outcomes and, in the second step, a binary measurement generates the outcome. Our experiment uses pairs of photonic qutrits distributed between two laboratories, where randomly chosen three-outcome measurements are performed. We report a violation by {9.3} standard deviations of the optimal inequality for nonsignaling binary correlations.
@article{arxiv.1712.06557,
title = {Observation of stronger-than-binary correlations with entangled photonic qutrits},
author = {Xiao-Min Hu and Bi-Heng Liu and Yu Guo and Guo-Yong Xiang and Yun-Feng Huang and Chuan-Feng Li and Guang-Can Guo and Matthias Kleinmann and Tamás Vértesi and Adán Cabello},
journal= {arXiv preprint arXiv:1712.06557},
year = {2018}
}