Abstract. Employing a recently proposed separability criterion we develop analytical lower bounds for the concurrence and for the entanglement of formation of bipartite quantum systems. The separability criterion is based on a nondecomposable positive map which operates on state spaces with even dimension, N ≥ 4, and leads to a class of nondecomposable optimal entanglement witnesses. It is shown that the bounds derived here complement and improve the existing bounds obtained from the criterion of positive partial transposition and from the realignment criterion.

PACS numbers: 03.67.Mn, 03.65.Ud, 03.65.Yz

Print publication: Issue 38 (22 September 2006)
Received 22 June 2006, in final form 9 August 2006
Published 5 September 2006