Non-Hermitian Hubbard model without the sign problem

TL;DR

This paper introduces a non-Hermitian Hubbard model with asymmetric hopping that eliminates the sign problem in quantum Monte Carlo simulations, enabling new studies of magnetic order suppression due to non-Hermiticity.

Contribution

It proposes a novel non-Hermitian Hubbard model with conjugate hopping terms to remove the sign problem in simulations, facilitating exploration of non-Hermitian effects.

Findings

Quantum Monte Carlo simulations are sign-problem free for this model.

Non-Hermiticity suppresses antiferromagnetic order.

The model enables studying non-Hermitian effects in strongly correlated systems.

Abstract

We study the Hubbard model with non-Hermitian asymmetric hopping terms. The conjugate hopping terms are introduced for two spin components so that the negative sign is canceled out. This ensures that the quantum Monte Carlo simulation is free from the negative sign problem. We analyze the antiferromagnetic order and its suppression by the non-Hermiticity.