Exploring boundaries of quantum convex structures: special role of unitary processes

Investor logo

Warning

This publication doesn't include Faculty of Economics and Administration. It includes Faculty of Informatics. Official publication website can be found on muni.cz.
Authors

PUCHAŁA Zbigniew JENCOVA Anna SEDLÁK Michal ZIMAN Mário

Year of publication 2015
Type Article in Periodical
Magazine / Source Phys. Rev. A
MU Faculty or unit

Faculty of Informatics

Citation
Web http://dx.doi.org/10.1103/PhysRevA.92.012304
Doi http://dx.doi.org/10.1103/PhysRevA.92.012304
Field Theoretical physics
Keywords quantum structure - quantum measurement - quantum information
Description We address the question of finding the most unbalanced convex decompositions into boundary elements (so-called boundariness) for sets of quantum states, observables, and channels. We show that in general convex sets the boundariness essentially coincides with the question of the most distinguishable element, thus providing an operational meaning for this concept. Unexpectedly, we discovered that for any interior point of the set of channels the most unbalanced decomposition necessarily contains a unitary channel. In other words, for any given channel the most distinguishable one is some unitary channel. Further, we prove that boundariness is submultiplicative under the composition of systems and explicitly evaluate its maximal value that is attained only for the most mixed elements of the considered sets.
Related projects:

You are running an old browser version. We recommend updating your browser to its latest version.