Finite-temperature tensor network study of the Hubbard model on an infinite square lattice

The Hubbard model is a longstanding problem in the theory of strongly correlated electrons and a very active one in the experiments with ultracold fermionic atoms. Motivated by current and prospective quantum simulations, we apply a two-dimensional tensor network-an infinite projected entangled pair state-evolved in imaginary time by the neighborhood tensor update algorithm working directly in the thermodynamic limit. With U(1) x U(1) symmetry and the bond dimensions up to 29, we generate thermal states down to the temperature of 0.17 times the hopping rate. We obtain results for spin and charge correlators, unaffected by boundary effects. The spin correlators-measurable in prospective ultracold atoms experiments attempting to approach the thermodynamic limit-provide evidence of disruption of the antiferromagnetic background with mobile holes in a slightly doped Hubbard model. The charge correlators reveal the presence of hole-doublon pairs near half filling and signatures of hole-hole repulsion on doping. We also obtain specific heat in the slightly doped regime.

Automated summary

In this study, a two-dimensional tensor network model was used to evolve the Hubbard model in an infinite projected entangled pair state. The results provide evidence of the disruption of the antiferromagnetic background and the presence of mobile holes in a slightly doped Hubbard model. The study also reveals the existence of hole-doublon pairs and hole-hole repulsion on doping.