Scalable programmable quantum gates and a new aspect of the additivity problem for the classical capacity of quantum channels

AJ Winter

Research output: Contribution to journalArticle (Academic Journal)peer-review

12 Citations (Scopus)

Abstract

We consider two apparently separated problems: in the first part of the article we study the concept of a scalable (approximate) programmable quantum gate (SPQG). These are special (approximate) programmable quantum gates, with nice properties that could have implications on the theory of universal computation. Unfortunately, as we prove, such objects do not exist in the domain of usual quantum theory. In the second part the problem of noisy dense coding (and generalizations) is addressed. We observe that the additivity problem for the classical capacity obtained is of apparently greater generality than for the usual quantum channel (completely positive maps): i.e., the latter occurs as a special case of the former, but, as we shall argue with the help of the nonexistence result of the first part, the former cannot be reduced to an instance of the latter. We conclude by suggesting that the additivity problem for the classical capacity of quantum channels, as posed until now, may conceptually not be in its appropriate generality. (C) 2002 American Institute of Physics.
Translated title of the contributionScalable programmable quantum gates and a new aspect of the additivity problem for the classical capacity of quantum channels
Original languageEnglish
Pages (from-to)4341 - 4352
JournalJournal of Mathematical Physics
Volume43 (9)
Publication statusPublished - Sep 2002

Bibliographical note

Publisher: Amer Inst Physics
Other identifier: IDS Number: 585ZC

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