2003/02/10 by Christopher King, C. King, King, C.
Computer Science · Mathematics · Physics and Astronomy · #Advanced Optimization Algorithms Research #FOS: Physical sciences #Mathematical Inequalities and Applications #Matrix Theory and Algorithms #Quantum Physics (quant-ph) #quant-ph
paper · pdf · doi:10.48550/arxiv.quant-ph/0302069
openalex publication_date 2003/02/10 · arxiv created 2003/02/17 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
This paper derives an inequality relating the p-norm of a positive 2 x 2 block matrix to the p-norm of the 2 x 2 matrix obtained by replacing each block by its p-norm. The inequality had been known for integer values of p, so the main contribution here is the extension to all values p >= 1. In a special case the result reproduces Hanner's inequality. As an application in quantum information theory, the inequality is used to obtain some results concerning maximal p-norms of product channels.