Local vertical measurements and violation of the Bell inequality

Better Bell Inequality Violation by Collective Measurements

The standard Bell inequality experiments test for violation of local realism by repeatedly making local measurements on individual copies of an entangled quantum state. Here we investigate the possibility of increasing the violation of a Bell inequality by making collective measurements. We show that the nonlocality of bipartite pure entangled states, quantified by their maximal violation of th...

Bipartite Bell Inequality and Maximal Violation

Entanglement estimation from Bell inequality violation

It is well known that the violation of Bell’s inequality in the form given by Clauser, Horne, Shimony, and Holt (CHSH) in two-qubit systems requires entanglement, but not vice versa, i.e., there are entangled states which do not violate the CHSH inequality. Here we compare some standard entanglement measures with violations of the CHSH inequality (as given by the Horodecki measure) for two-qubi...

Violation of the Bell-Inequality in Supercorrelated Systems

We present realistic physical systems in which the Bell inequality can be strongly violated, even if they are local and classical (the violation can be stronger than in the case of the singlet state). The essential characteristic of these systems is that they exhibit full pairwise correlation between all system variables. The origin of the violation of the Bell inequality is quantitatively inve...

Violation of Bell inequality and entanglement of decaying Werner states

Bell-inequality violation and entanglement, measured by Wootters’ concurrence and negativity, of two qubits initially in Werner or Werner-like states coupled to thermal reservoirs are analyzed within the master equation approach. It is shown how this simple decoherence process leads to generation of states manifesting the relativity of two-qubit entanglement measures.  2004 Elsevier B.V. All r...