Exact eigenstates of extended SU($N$) Hubbard models: Generalizations of $\eta$-pairing states with $N$-particle off-diagonal long-range order

TL;DR

This paper constructs exact high-energy eigenstates in extended SU(N) Hubbard models, generalizing $ta$-pairing states, revealing distinct long-range order behaviors for even and odd N, and proving their uniqueness as ground states.

Contribution

It introduces N-particle $ta$-pairing states as exact eigenstates of extended SU(N) Hubbard models, analyzing their correlation properties and ground state uniqueness.

Findings

Even N states show off-diagonal long-range order.

Odd N states have exponential decay in bulk correlations.

States are proven to be unique ground states of specific Hamiltonians.

Abstract

We consider $N$-particle generalizations of $\eta$-pairing states in a chain of $N$-component fermions and show that these states are exact (high-energy) eigenstates of an extended SU($N$) Hubbard model. We compute the singlet correlation function of the states and find that its behavior is qualitatively different for even and odd $N$. When $N$ is even, these states exhibit off-diagonal long-range order in $N$-particle reduced density matrix. On the other hand, when $N$ is odd, the correlations decay exponentially with distance in the bulk, but end-to-end correlations do not vanish in the thermodynamic limit. Finally, we prove that these states are the unique ground states of suitably tailored Hamiltonians.