Scaling, entanglement, and quantum phase transitions

In this paper we discuss the entanglement near a quantum phase transition by analyzing the properties of the concurrence for a class of exactly solvable models in one dimenion. Entanglement can be classified in the framework of the scaling theory of phase transition. There is a profound difference between the classical correlations, whose correlation length diverges at the phase transiton, and non-local quantum correlations that remain, in general, short ranged.