An alternative approach to generalized complementarity

Ghenadie N. Mardari

Walter M. Elsasser

Lucien Morren

Towfic Shomar

K. M. Fonseca-Romero, J. G. G. de Oliveira, J. G. Peixoto de Faria +1 more

In two-dimensional systems, predictability and visibility satisfy a complementarity relation, which has been generalized to bipartite systems by including the concurrence. We consider systems in which the two alternatives of a which-state experiment are nonorthogonal states and propose generalized measures of predictability and visibility. Criteria like symmetry under exchange of the alternatives, vanishing visibility when only one of the alternatives is present, and clear operational meaning, favor definitions of predictability and visibility which use a three-dimensional basis, previously employed in the unambiguous discrimination of nonorthogonal states. We derive generalized single-partite and bipartite complementarity relations and find that predictability and visibility do not exhaust the single-partite properties for a nonorthogonal basis. A recent experiment on the quantum-classical border is analyzed using generalized complementarity relations.

Anthony Chefles, Stephen Mark Barnett

The least upper bound in Cirel'son's quantum generalization of the local-realistic Bell inequality is intermediate between the local-realistic and general probablistic limits. An alternative derivation of Cirel'son's inequality is presented which sheds light on the role played by complementarity in determining this bound and the fact that it falls short of the general probablistic limit.