The Saturation of Several Universal Inequalities in Information-Processing

Lin Zhang, Junde Wu, and Shao-Ming Fei

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Submission date: 12. Aug. 2015
Pages: 12
published in: Communications in theoretical physics, 63 (2015) 4, p. 427-430 
DOI number (of the published article): 10.1088/0253-6102/63/4/427
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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.