- Letter
Tackling the sign problem in the doped Hubbard model with normalizing flows
Phys. Rev. B 114, L231117 – Published 30 October, 2026
DOI: https://doi.org/10.1103/93pv-5hlm
Abstract
The Hubbard model at finite chemical potential is a cornerstone for understanding doped correlated systems, but simulations are severely limited by the sign problem. In the auxiliary-field formulation, the spin basis mitigates the sign problem, yet severe ergodicity issues have limited its use. We extend recent advances with normalizing flows at half filling to finite chemical potential by introducing an annealing scheme enabling ergodic sampling. Compared to state-of-the-art hybrid Monte Carlo in the charge basis, our approach accurately reproduces exact diagonalization results while reducing statistical uncertainties by an order of magnitude, opening another path for simulations of doped correlated systems.