Measurable entanglement

Abstract

The amount of entanglement carried by a quantum bipartite state is usually evaluated in terms of concurrence [S. Hill and W. K. Wootters, Phys. Rev. Lett. 78, 5022 (1997); P. Rungta, V. Bužek, C. M. Caves, M. Hillery, and G. J. Milburn, Phys. Rev. A 64, 042315 (2001)]. We give a physical interpretation of concurrence that reveals a way of its direct measurement and discuss possible generalizations.