Largest separable balls around the maximally mixed bipartite quantum state
Abstract
For finite-dimensional bipartite quantum systems, we find the exact size of the largest balls, in spectral norms for , of separable (unentangled) matrices around the identity matrix. This implies a simple and intutively meaningful geometrical sufficient condition for separability of bipartite density matrices: that their purity not be too large. Theoretical and experimental applications of these results include algorithmic problems such as computing whether or not a state is entangled, and practical ones such as obtaining information about the existence or nature of entanglement in states reached by NMR quantum computation implementations or other experimental situations.
Cite
@article{arxiv.quant-ph/0204159,
title = {Largest separable balls around the maximally mixed bipartite quantum state},
author = {Leonid Gurvits and Howard Barnum},
journal= {arXiv preprint arXiv:quant-ph/0204159},
year = {2009}
}
Comments
7 pages, LaTeX. Motivation and verbal description of results and their implications expanded and improved; one more proof included. This version differs from the PRA version by the omission of some erroneous sentences outside the theorems and proofs, which will be noted in an erratum notice in PRA (and by minor notational differences)