O. Guehne, P. Hyllus, D. Bruss, A. Ekert, M. Lewenstein, C. Macchiavello, A. Sanpera
Published 2002-10-18, updated 2003-06-26Version 2
In this paper we address the problem of detection of entanglement using only few local measurements when some knowledge about the state is given. The idea is based on an optimized decomposition of witness operators into local operators. We discuss two possible ways of optimizing this local decomposition. We present several analytical results and estimates for optimized detection strategies for NPT states of 2x2 and NxM systems, entangled states in 3 qubit systems, and bound entangled states in 3x3 and 2x4 systems.
Comments: 24 pages, 2 figures. Contribution to the proceedings of the International Conference on Quantum Information in Oviedo, Spain (July 13-18, 2002). Error in W_W1-witness Eq. (35) corrected as well as minor typos. Reference added
Journal: J. Mod. Opt. 50 (6-7), 1079-1102, (2003)
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