Entanglement Properties and Phase Diagram of the Two-Orbital Atomic Hubbard Model

TL;DR

This paper investigates the entanglement and phase transitions in a two-orbital Hubbard model at zero kinetic energy, revealing a singlet-triplet transition and linking entanglement entropy to criticality.

Contribution

It provides the first detailed phase diagram of the two-orbital Hubbard model in the zero kinetic energy limit, highlighting the entanglement properties at the transition.

Findings

Identifies a singlet-triplet transition at a critical V/J ratio.

Shows a jump in entanglement entropy at the phase boundary.

Establishes a connection between entanglement and criticality in the model.

Abstract

We study the two-orbital Hubbard model in the limit of vanishing kinetic energy. The phase diagram in the $V-J$ plane, with $V$ and $J$ denoting the interorbital hybridization and exchange coupling respectively, at half filling is obtained. A singlet(dimer)-triplet transition is found for a critical value of the ratio $V/J.$ The entropy of formation, both in the mode and in the particle picture, presents a jump as the same critical line in conformity with the suggested relation between criticality and entanglement.