More efficient Bell inequalities for Werner states

TL;DR

This paper introduces new Bell inequalities that demonstrate nonlocality in Werner states over a broader parameter range than the traditional CHSH inequality, advancing understanding of quantum nonlocality.

Contribution

The authors develop more efficient Bell inequalities that extend the nonlocality detection range for Werner states beyond the CHSH limit.

Findings

Bell inequalities violate Werner states for 0.7056<p<1

Wider violation range than CHSH inequality

Answers Gisin's question positively

Abstract

In this paper we study the nonlocal properties of two-qubit Werner states parameterized by the visibility parameter 0<p<1. New family of Bell inequalities are constructed which prove the two-qubit Werner states to be nonlocal for the parameter range 0.7056<p<1. This is slightly wider than the range 0.7071<p<1, corresponding to the violation of the Clauser-Horne-Shimony-Holt (CHSH) inequality. This answers a question posed by Gisin in the positive, i.e., there exist Bell inequalities which are more efficient than the CHSH inequality in the sense that they are violated by a wider range of two-qubit Werner states.