Projection of infinite-U Hubbard model and algebraic sign structure

We propose a projection approach to perform quantum Monte Carlo (QMC) simulation on the infinite-U Hubbard model at some integer fillings where either it is sign problem free or surprisingly has an algebraic sign structure-a power law dependence of average sign on system size. We demonstrate our scheme on the infinite-U SU (2N) fermionic Hubbard model on both a square and honeycomb lattice at half filling, where it is sign problem free, and suggest possible correlated ground states. The method can be generalized to study certain extended Hubbard models applying to cluster Mott insulators or two-dimensional Moire systems; among one of them at certain non-half-integer filling, the sign has an algebraic behavior such that it can be numerically solved within a polynomial time. Further, our projection scheme can also be generalized to implement the Gutzwiller projection to spin basis such that SU (2N) quantum spin models and Kondo lattice models may be studied in the framework of fermionic QMC simulations.

Automated summary

The paper introduces a projection approach for quantum Monte Carlo simulation of the infinite-U Hubbard model at some integer fillings, addressing sign problem and algebraic sign structure. It demonstrates the method on the infinite-U SU (2N) fermionic Hubbard model at half filling, suggesting possible correlated ground states. The scheme can be generalized to study extended Hubbard models and implement Gutzwiller projection to spin basis for studying SU (2N) quantum spin models and Kondo lattice models.