A monotonicity version of a concavity theorem of Lieb

TL;DR

This paper presents a simplified proof of a strengthened version of Lieb's theorem, which is crucial for understanding the properties of quantum entropy and its subadditivity.

Contribution

It introduces a monotonicity-based approach to a classical concavity theorem, enhancing the original result with a more straightforward proof.

Findings

Simplified proof of a strengthened Lieb theorem

Enhanced understanding of quantum entropy properties

Implications for quantum information theory

Abstract

We give a simple proof of a strengthened version of a theorem of Lieb that played a key role in the proof of strong subadditivity of the quantum entropy.