Collective measurements on large quantum systems together with a majority voting strategy can lead to a violation of the CHSH Bell inequality. In presence of many entangled pairs, this violation decreases quickly with the number of pairs, and vanishes for some critical pair number that is a function of the noise present in the system. Here, we show that a different binning strategy can lead to a more substantial Bell violation when the noise is sufficiently small. Given the relation between the critical pair number and the source noise, we then present an experiment where the critical pair number is used to quantify the quality of a high visibility photon pair source. Our results demonstrate nonlocal correlations using collective measurements operating on clusters of more than 40 photon pairs.
@article{arxiv.1704.00969,
title = {Experimental many-pairs nonlocality},
author = {Hou Shun Poh and Alessandro Cerè and Jean-Daniel Bancal and Yu Cai and Nicolas Sangouard and Valerio Scarani and Christian Kurtsiefer},
journal= {arXiv preprint arXiv:1704.00969},
year = {2017}
}