Doping two-dimensional Fermi-Hubbard systems from polaronic metal to Fermi liquid

The Fermi-Hubbard model is believed to capture the essential ingredients of phenomena like high-Tc superconductivity, yet a complete understanding of its phases emerging upon doping remains elusive. Using our Fermi gas microscope with full spin and density resolution, we investigate the influence of different doping levels in a two-dimensional antiferromagnetic Hubbard system at temperatures around the superexchange energy. We observe the crossover from an anomalous metal to a conventional Fermi liquid.  In order to obtain a better understanding of the nature of charge carriers within this crossover, we study the transformation of multi-point correlations between spins and holes. Starting from a magnetic polaron regime, we find the system evolves into a Fermi liquid featuring incommensurate magnetic fluctuations and fundamentally altered correlations. The crossover is completed for hole dopings around 30%. We benchmark theoretical approaches and discuss possible connections to lower temperature phenomena.