Revisiting the equality conditions of the data processing inequality for the sandwiched Rényi divergence

Abstract

We provide a transparent, simple and unified treatment of recent results on the equality conditions for the data processing inequality (DPI) of the sandwiched quantum Rényi divergence, including the statement that equality in the data processing implies recoverability via the Petz recovery map for the full range of $\alpha$ recently proven by Jen\v cová. We also obtain a new set of equality conditions, generalizing a previous result by Leditzky et al.

11 pages, no figures. Comments are welcome. v2: references updated

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Cited by in corpus (1)

• Geometric conditions for saturating the data processing inequality