Physics – Quantum Physics
Scientific paper
2003-06-29
Commun. Math. Phys. v. 249,417-430, 2004
Physics
Quantum Physics
19 pages; substantially revised and enhanced. To appear in Commun. Math. Phys
Scientific paper
10.1007/s00220-004-1116-5
In this paper we give several equivalent formulations of the additivity conjecture for constrained channels, which formally is substantially stronger than the unconstrained additivity. To this end a characteristic property of the optimal ensemble for such a channel is derived, generalizing the maximal distance property. It is shown that the additivity conjecture for constrained channels holds true for certain nontrivial classes of channels. Recently P. Shor showed that conjectured additivity properties for several quantum information quantities are in fact equivalent. After giving an algebraic formulation for the Shor's channel extension, its main asymptotic property is proved. It is then used to show that additivity for two constrained channels can be reduced to the same problem for unconstrained channels, and hence, "global" additivity for channels with arbitrary constraints is equivalent to additivity without constraints.
Holevo Alexander S.
Shirokov M. E.
No associations
LandOfFree
On Shor's channel extension and constrained channels does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with On Shor's channel extension and constrained channels, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and On Shor's channel extension and constrained channels will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-32274