| The most important property of multi-component quantum systems is entanglement, which corresponds to quantum correlations between particles or, more generally, subsystems. The degree of entanglement is intimately connected to all multi-component quantum systems and to the efficiency of numerical algorithms developed to simulate such systems. Recently, we have applied the two-site mutual information to spin and fermionic systems and have generalized it to models in which bosonic and fermionic modes are coupled. In this talk, we present an overview of quantum information entropy-based analysis of quantum phase transitions in various strongly correlated lattice models and of the electronic structures of molecules. In particular, we discuss the relevance of umklapp processes in the one-dimensional repulsive SU(n) Hubbard model for n=3,4, and 5 for commensurate fillings f=p/q, where p and q are relatively prime. We show recent results on low dimensional frustrated spin and ladder models and on transition metal clusters. Since the measures of entanglement are strongly related coupled to the formulation of numerical procedures for approximating the electronic wave function, we also present recent developments on a Tree-Tensor-Network-State (TTNS) approach to simulate strongly correlated systems with nonlocal interactions in higher dimensions. |
|