2005/11/30 by Man-Duen Choi, David W. Kribs, Karol Zyczkowski
Mathematics · Physics and Astronomy · #math.FA #math.OA #quant-ph
published as Lin. Alg. Appl., 418 (2006), 828-839. · 14 pages, 3 figures, to appear in Linear Algebra and its Applications
arxiv created 2006/04/02 · arxiv updated 2009/12/01
We consider higher-rank versions of the standard numerical range for matrices. A central motivation for this investigation comes from quantum error correction. We develop the basic structure theory for the higher-rank numerical ranges, and give a complete description in the Hermitian case. We also consider associated projection compression problems.