Demonstrating nonlocal correlations in a multipartite scenario with randomly chosen local measurements

Shih-Xian Yang^1*, Yeong-Cherng Liang¹

¹Department of Physics, National Cheng Kung University, Tainan, Taiwan

* Presenter:Shih-Xian Yang, email:l26061016@mail.ncku.edu.tw

We consider the problem of demonstrating non-Bell-local correlations by performing local measurements in randomly chosen bases on a multipartite Greenberger-Horne-Zeilinger state. Inspired by previous work in the bipartite scenario, we consider specifically the case where each party performs measurements on bases that form a triad on the Bloch sphere. As with the bipartite scenario, our numerical results for the tripartite, and the 4-partite scenario suggests that if each triad is randomly, but uniformly chosen according to the Haar measure, one always (except possibly for a set of measure zero) finds correlations that violate a Bell inequality. In addition, these quantum violations of a Bell inequality appear to be fairly resistant to white noise, indicating that such a demonstration can in principle be performed in an experimental situation without sharing a global reference frame.

Keywords: Bell inequalities, quantum entanglement