Quantum f-divergences via Nussbaum–Szkoła distributions and applications to f-divergence inequalities
Abstract
The main result in this paper shows that the quantum f-divergence of two states is equal to the classical f-divergence of the corresponding Nussbaum–Szkoła distributions. This provides a general framework for studying certain properties of quantum entropic quantities using the corresponding classical entities. The usefulness of the main result is illustrated by obtaining several quantum f-divergence inequalities from their classical counterparts. All results presented here are valid in both finite and infinite dimensions and hence can be applied to continuous variable systems as well. A comprehensive review of the instances in the literature where Nussbaum–Szkoła distributions are used, is also provided in this paper.
In memory of K. R. Parthasarathy