0205064v2

related topics
{information, entropy, channel}
{let, theorem, proof}
{observables, space, algebra}
{operator, operators, space}
{vol, operators, histories}
{group, space, representation}
{equation, function, exp}
{measurement, state, measurements}

Inequalities for Quantum Entropy: A Review with Conditions for Equality

Mary Beth Ruskai

abstract: This paper presents self-contained proofs of the strong subadditivity inequality for quantum entropy and some related inequalities for the quantum relative entropy, most notably its convexity and its monotonicity under stochastic maps. Moreover, the approach presented here, which is based on Klein's inequality and one of Lieb's less well-known concave trace functions, allows one to obtain conditions for equality. Using the fact that the Holevo bound on the accessible information in a quantum ensemble can be obtained as a consequence of the monotonicity of relative entropy, we show that equality can be attained for that bound only when the states in the ensemble commute. The paper concludes with an Appendix giving a short description of Epstein's elegant proof of the relevant concavity theorem of Lieb.

oai_identifier:
oai:arXiv.org:quant-ph/0205064
categories:
quant-ph math-ph math.MP
comments:
28 pages, latex Added reference to M.J.W. Hall, "Quantum Information and Correlation Bounds" Phys. Rev. A, 55, pp 100--112 (1997)
doi:
10.1063/1.1497701
arxiv_id:
quant-ph/0205064
journal_ref:
J. Math. Phys. 43, 4358-4375 (2002); erratum 46, 019901 (2005).
created:
2002-05-12
updated:
2002-05-19

Full article ▸

related documents
9809010v1
0411093v1
9609024v3
9911079v3
0505151v1
0011072v2
9911009v1
0410091v2
0402178v3
0511219v3
0608074v3
0306196v2
0401187v3
0405149v1
0409106v3
0412006v2
0509016v2
0409207v3
0306083v1
0307104v3
0210190v1
0412157v1
0207010v1
0403092v1
0702059v3