General Entanglement Breaking Channels
Abstract
This paper studies the class of stochastic maps, or channels, whose action (when tensored with the identity) on an entangled state always yields a separable state. Such maps have a canonical form introduced by Holevo. Such maps are called entanglement breaking, and can always be written in a canonical form introduced by Holevo. Some special classes of these maps are considered and several equivalent characterizations given. Since the set of entanglement-breaking trace-preserving maps is convex, it can be described by its extreme points. The only extreme points of the set of completely positive trace preserving maps which are also entanglement breaking are those known as classical quantum or CQ. However, for d > 2 the set of entanglement breaking maps has additional extreme points which are not extreme CQ maps.
Keywords
Cite
@article{arxiv.quant-ph/0302031,
title = {General Entanglement Breaking Channels},
author = {Michael Horodecki and Peter W. Shor and Mary Beth Ruskai},
journal= {arXiv preprint arXiv:quant-ph/0302031},
year = {2009}
}
Comments
This paper extends the results in section 3 of quant-ph/0207100, and gives a counter-example to the conjecture that all extreme points are CQ. Final version to appear in Rev. Math. Phys