Evidence for valence-bond pairing in a one-dimensional two-orbital system

TL;DR

This paper provides evidence that valence-bond states can serve as ground states with pairing tendencies in a one-dimensional two-orbital Hubbard model, supporting their potential role in high-temperature superconductivity.

Contribution

It demonstrates the existence of a valence-bond ground state with pairing tendencies in a two-orbital Hubbard model, linking valence bonds to topological order and edge states.

Findings

Valence-bond ground state observed at finite doping.

Evidence of topological order associated with VB states.

Support for VB pairing mechanism in fermionic systems.

Abstract

Valence bond (VB) states as the formation mechanism of Cooper pairs, eventually leading to high-temperature superconductivity, remain a controversial topic. Although various VB-like states find variational relevance in the description of specific spin models and quantum spin liquids, in the realm of many-body fermionic Hamiltonians, the evidence for such states as ground states wave functions remains elusive, challenging the valence-bond pairing mechanism. Here, we present evidence of a VB ground state with pairing tendencies, particularly at finite doping. We achieved this for the generic two-orbital Hubbard model in low dimension, where the VB states can be associated with the presence of the topological order manifested by edge states.