title: Density of states of quantum spin systems from isotropic entanglement.
abstract: We propose a method that we call isotropic entanglement (IE), which predicts the eigenvalue distribution of quantum many body (spin) systems with generic interactions. We interpolate between two known approximations by matching fourth moments. Though such problems can be QMA-complete, our examples show that isotropic entanglement provides an accurate picture of the spectra well beyond what one expects from the first four moments alone. We further show that the interpolation is universal, i.e., independent of the choice of local terms.
authors.affiliation: Department of Mathematics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA. ramis@mit.edu
authors.forename: Ramis
authors.initials: R
authors.lastname: Movassagh
authors.forename: Alan
authors.initials: A
authors.lastname: Edelman