Two-site entropy and quantum phase transitions in low-dimensional models

TL;DR

This paper introduces a novel two-site entropy method to detect quantum phase transitions in low-dimensional models, outperforming traditional indicators and compatible with DMRG techniques.

Contribution

The authors present a new two-site entropy approach that effectively identifies quantum phase transitions in fermionic and spin models, enhancing existing detection methods.

Findings

Two-site entropy reliably signals quantum phase transitions.

The method outperforms gap and order parameter calculations.

Compatible with DMRG algorithms.

Abstract

We propose a new approach to study quantum phase transitions in low-dimensional lattice models. It is based on studying the von Neumann entropy of two neighboring central sites in a long chain. It is demonstrated that the procedure works equally well for fermionic and spin models, and the two-site entropy is a better indicator of quantum phase transition than calculating gaps, order parameters or the single-site entropy. The method is especially convenient when the density-matrix renormalization-group (DMRG) algorithm is used.