Abstract
A necessary and sufficient entanglement criterion based on variances of Mermin-Klyshko’s Bell operators is proved for multiqubit pure states. Contrary to Bell’s inequalities, entangled pure states strictly satisfy a quadratic inequality but product ones can attain the equality under some local unitary transformations, which can be obtained by solving a quadratic maximum problem. This presents a characterization of multiqubit pure-state entanglement.
- Received 13 January 2006
DOI:https://doi.org/10.1103/PhysRevA.73.034306
©2006 American Physical Society