Department of Science, Zhijiang College, Zhejiang University of Technology, Hangzhou 310024, China.
Phys Rev Lett. 2012 Nov 16;109(20):200503. doi: 10.1103/PhysRevLett.109.200503.
Entanglement monotones, such as the concurrence, are useful tools to characterize quantum correlations in various physical systems. The computation of the concurrence involves, however, difficult optimizations and only for the simplest case of two qubits a closed formula was found by Wootters [Phys. Rev. Lett. 80, 2245 (1998)]. We show how this approach can be generalized, resulting in lower bounds on the concurrence for higher dimensional systems as well as for multipartite systems. We demonstrate that for certain families of states our results constitute the strongest bipartite entanglement criterion so far; moreover, they allow us to recognize novel families of multiparticle bound entangled states.
纠缠单调，如并协，是用于描述各种物理系统中量子相关性的有用工具。然而，计算并协涉及困难的优化，并且仅在最简单的情况下，即两个量子比特的情况下，Wootters [Phys. Rev. Lett. 80, 2245 (1998)]找到了一个封闭的公式。我们展示了如何推广这种方法，从而得到更高维系统和多部分系统的并协的下界。我们证明，对于某些态族，我们的结果构成了迄今为止最强的两部分纠缠判据；此外，它们使我们能够识别新的多粒子束缚纠缠态家族。
