Ground-state phase diagram of the square lattice Hubbard model from density matrix embedding theory

TL;DR

This study uses density matrix embedding theory to map the ground-state phase diagram of the square lattice Hubbard model, revealing superconductivity and competing states with reliable error estimates.

Contribution

It provides the first detailed phase diagram of the Hubbard model on the square lattice with error quantification using clusters up to 16 sites.

Findings

Superconductivity observed in the ground state.

Competition between charge, spin, and pairing states.

Errors below the critical temperature in cuprates.

Abstract

We compute the ground-state phase diagram of the Hubbard and frustrated Hubbard models on the square lattice with density matrix embedding theory using clusters of up to 16 sites. We provide an error model to estimate the reliability of the computations and complexity of the physics at different points in the diagram. We find superconductivity in the ground-state as well as competition between inhomogeneous charge, spin, and pairing states at low doping. The estimated errors in the study are below T$_c$ in the cuprates and on the scale of contributions in real materials that are neglected in the Hubbard model.