title: Two-point versus multipartite entanglement in quantum phase transitions.
abstract: We analyze correlations between subsystems for an extended Hubbard model exactly solvable in one dimension, which exhibits a rich structure of quantum phase transitions (QPTs). The T = 0 phase diagram is exactly reproduced by studying singularities of single-site entanglement. It is shown how comparison of the latter quantity and quantum mutual information allows one to recognize whether two-point or shared quantum correlations are responsible for each of the occurring QPTs. The method works in principle for any number D of degrees of freedom per site. As a by-product, we are providing a benchmark for direct measures of bipartite entanglement; in particular, here we discuss the role of negativity at the transition.
authors.affiliation: Dipartimento di Fisica del Politecnico, Corso Duca degli Abruzzi 24, I-10129 Torino, Italy.
authors.forename: Alberto
authors.initials: A
authors.lastname: Anfossi
authors.forename: Paolo
authors.initials: P
authors.lastname: Giorda
authors.forename: Arianna
authors.initials: A
authors.lastname: Montorsi
authors.forename: Fabio
authors.initials: F
authors.lastname: Traversa