2012/08/31 by Michael Walter, Brent Doran, David Gross +1 · 2 citations
Physics and Astronomy · Mathematics · #quant-ph #math-ph #math.MP
paper · pdf · doi:10.1126/science.1232957
published as Science, vol. 340, no. 6137, pp. 1205-1208 (2013) · 25 pages, 7 figures
arxiv created 2014/11/14 · arxiv updated 2014/11/17
Entangled many-body states are an essential resource for quantum computing and interferometry. Determining the type of entanglement present in a system usually requires access to an exponential number of parameters. We show that in the case of pure multi-particle quantum states, features of the global entanglement can already be extracted from local information alone. This is achieved by associating with any given class of entanglement an entanglement polytope---a geometric object which characterizes the single-particle states compatible with that class. Our results, applicable to systems of arbitrary size and statistics, give rise to local witnesses for global pure-state entanglement, and can be generalized to states affected by low levels of noise.