Bounds of the Pinsker and Fannes Types on the Tsallis Relative Entropy

Alexey E. Rastegin

Published 2011-02-25, updated 2013-08-16Version 3

Pinsker's and Fannes' type bounds on the Tsallis relative entropy are derived. The monotonicity property of the quantum $f$-divergence is used for its estimating from below. For order $\alpha\in(0,1)$, a family of lower bounds of Pinsker type is obtained. For $\alpha>1$ and the commutative case, upper continuity bounds on the relative entropy in terms of the minimal probability in its second argument are derived. Both the lower and upper bounds presented are reformulated for the case of R\'{e}nyi's entropies. The Fano inequality is extended to Tsallis' entropies for all $\alpha>0$. The deduced bounds on the Tsallis conditional entropy are used for obtaining inequalities of Fannes' type.