Random Bipartite Entanglement from W and W-Like States

作     者：Ben Fortescue Hoi-Kwong Lo 

作者机构：Center for Quantum Information and Quantum Control Department of Electrical and Computer Engineering and Department of Physics University of Toronto Toronto Ontario M5S 3G4 Canada 

出 版 物：《Physical Review Letters》 (Phys Rev Lett)

年 卷 期：2007年第98卷第26期

页      面：260501-260501页

核心收录：

学科分类：07[理学] 0702[理学-物理学] 

主　　题：Quantum theory 

摘      要：We describe a protocol for distilling maximally entangled bipartite states between random pairs of parties from those sharing a tripartite W state |W⟩=(1/3)(|100⟩+|010⟩+|001⟩)ABC, and show that the total distillation rate Et∞ [the total number of Einstein-Podolsky-Rosen (EPR) pairs distilled per W, irrespective of who shares them] may be done at a higher rate than EPR distillation between specified pairs of parties. Specifically, the optimal rate for distillation to specified parties has been previously shown to be 0.92 EPR pairs per W, while our protocol can asymptotically distill 1 EPR pair per W between random pairs of parties, which we conjecture to be optimal. We thus demonstrate a tradeoff between overall distillation rate and final distribution of EPR pairs. We further show that there exist states with fixed lower-bounded Et∞, but arbitrarily small distillable entanglement for specified parties.