Optimal entanglement transformations among N-qubit W-class states

作     者：Wei Cui Eric Chitambar Hoi-Kwong Lo 

作者机构：[]Center for Quantum Information and Quantum Control （CQIQC） Department of Physics and Department of Electrical & Computer Engineering University of Toronto Toronto Ontario M5S 3G4 Canada 

出 版 物：《Physical Review A》 (物理学评论A辑：原子、分子和光学物理学)

年 卷 期：2010年第82卷第6期

页      面：062314-062314页

核心收录：

学科分类：070207[理学-光学] 07[理学] 08[工学] 0803[工学-光学工程] 0702[理学-物理学] 

基　　金：CIFAR CRC NSERC QuantumWorks 

主　　题：Quantum entanglement 

摘      要：We investigate the physically allowed probabilities for transforming one N-partite W-class state to another by means of local operations assisted with classical communication. Recently, S. Kintaş and S. Turgut [J. Math. Phys. 51, 092202 (2010)] obtained an upper bound for the maximum probability of transforming two such states. Here, we provide a simple sufficient and necessary condition for when this upper bound can be satisfied and, thus, when optimality of state transformation can be achieved. Our discussion involves obtaining lower bounds for the transformation of arbitrary W-class states and showing precisely when this bound saturates the bound of Kintaş and Turgut. Finally, we consider the question of transforming symmetric W-class states and find that, in general, the optimal one-shot procedure for converting two symmetric states requires a nonsymmetric filter by all the parties.