One-dimensional extended Hubbard model with spin-triplet pairing ground states

TL;DR

This paper demonstrates that the one-dimensional extended Hubbard model can exhibit ferromagnetic ground states with spin-triplet pairing, explicitly constructs these states, and explores symmetry-breaking states related to Majorana fermions and the Kitaev chain.

Contribution

It provides explicit constructions of ground states with spin-triplet pairing and symmetry breaking in the extended Hubbard model, connecting to Majorana fermions and topological superconductivity.

Findings

Existence of saturated ferromagnetic ground states with spin-triplet pairing.

Explicit wave functions for fixed electron numbers.

Connection to Majorana fermions and the Kitaev chain.

Abstract

We show that the one-dimensional extended Hubbard model has saturated ferromagnetic ground states with the spin-triplet electron pair condensation in a certain range of parameters. The ground state wave functions with fixed electron numbers are explicitly obtained. We also construct two ground states in which both the spin-rotation and the gauge symmetries are broken, and show that these states are transferred from one to the other by applying the edge operators. The edge operators are reduced to the Majorana fermions in a special case. These symmetry breaking ground states are shown to be stabilized by a superconducting mean field Hamiltonian which is related to the Kitaev chain with the charge-charge interaction.