Research problems on numerical ranges in quantum computing
David W. Kribs, Aron Pasieka, Martin Laforest, Colm A. Ryan, Marcus P. da Silva · Linear and Multilinear Algebra · 2009
We describe some instances in quantum information processing where numerical range techniques arise. We focus on two basic settings: higher-rank numerical ranges and their relevance in theoretical quantum error correction, and the classical numerical range and its use for comparing quantum information processing operations. We present the basic theory, discuss examples and formulate open problems.