%0 Journal Article
%T A criterion for entanglement in two two-level systems
%A E. Ferraro
%A A. Napoli
%A A. Messina
%J Mathematics
%D 2007
%I arXiv
%X We prove a necessary and sufficient condition for the occurrence of entanglement in two two-level systems, simple enough to be of experimental interest. Our results are illustrated in the context of a spin star system analyzing the exact entanglement evolution of the central couple of spins.
%U http://arxiv.org/abs/0706.4399v1