To what extent do mixed states violate the Bell inequalities?

P. K. Aravind

Ryszard Horodecki, Paweł Horodecki, Michał Horodecki

A. Mann, Ko Nakamura, M. Revzen

Violation of Bell's inequality for mixed states is considered. The authors show that a mixture of states that are macroscopically essentially equivalent may suppress the violation. Thus in general the inequality will not be violated by mixed states (except very special ones).

Antonio Mandarino, Giovanni Scala

The theorem developed by John Bell constituted the starting point of a revolution that translated a philosophical question about the nature of reality into the broad and intense field of research of the quantum information technologies. We focus on a system of two qubits prepared in a random, mixed state, and we study the typical behavior of their nonlocality via the CHSH-Bell inequality. Afterward, motivated by the necessity of accounting for inefficiency in the state preparation, we address to what extent states close enough to one with a high degree of nonclassicality can violate local realism with a previously chosen experimental setup.

Sandu Popescu, Rohrlich, D

Chang‐shui Yu, He‐Shan Song

In this paper, we present a generalized Bell inequality for mixed states. The distinct characteristic is that the inequality has variable bound depending on the decomposition of the density matrix. The inequality has been shown to be more refined than the previous Bell inequality. It is possible that a separable mixed state can violate the Bell inequality.