We have decided to discontinue the publication of preprints on our preprint server as of 1 March 2024. The publication culture within mathematics has changed so much due to the rise of repositories such as ArXiV (www.arxiv.org) that we are encouraging all institute members to make their preprints available there. An institute's repository in its previous form is, therefore, unnecessary. The preprints published to date will remain available here, but we will not add any new preprints here.
MiS Preprint
38/2015
The Saturation of Several Universal Inequalities in Information-Processing
Lin Zhang, Junde Wu and Shao-Ming Fei
Abstract
Strong subadditivity inequality of quantum entropy, proved by Lieb and Ruskai, is a powerful tool in quantum information theory. The fact that the strong subadditivity inequality saturated only by so-called Markov states is obtained in the recent literature [P. Hayden et al., Commun. Math. Phys. 246, 359 (2004).].
In this paper, we give a characterization of another equivalent version for strong subadditivity inequality. We discuss the coherent information saturating its upper bound as well. A necessary and sufficient condition for this saturation is derived. The possible applications are discussed.