LOWER BOUND FOR ACCESSIBLE INFORMATION IN QUANTUM-MECHANICS

Citation
R. Jozsa et al., LOWER BOUND FOR ACCESSIBLE INFORMATION IN QUANTUM-MECHANICS, Physical review. A, 49(2), 1994, pp. 668-677
Citations number
39
Categorie Soggetti
Physics
Journal title
ISSN journal
10502947
Volume
49
Issue
2
Year of publication
1994
Pages
668 - 677
Database
ISI
SICI code
1050-2947(1994)49:2<668:LBFAII>2.0.ZU;2-9
Abstract
It has long been known that the von Neumann entropy S is an upper boun d on the information one can extract from a quantum system in an unkno wn pure state. In this paper we define the ''subentropy'' Q, which we prove to be a lower bound on this information. Moreover, just as the v on Neumann entropy is the best upper bound that depends only on the de nsity matrix, we show that Q is the best lower bound that depends only on the density matrix. Other parallels between S and Q are also demon strated.