Coupled spin and density dynamics in a minimally doped Fermi-Hubbard system

The Fermi-Hubbard model is one of the simplest models capturing the spin and density dynamics occurring in highly-correlated electronic systems. Understanding its transport properties may shed light on emergent phenomena in cuprate materials, including bad metallic behavior and high-temperature superconductivity. Yet this task is notoriously challenging away from half-filling, even in the minimal case where a Mott insulator is doped with a single, initially localized hole.

We report on the site-resolved dynamics of a hole deterministically created in a half-filled 2D lattice of about 400 lithium-6 atoms with antiferromagnetic order. We observe an initial hole expansion determined by the tunneling rate, followed by a slowdown that strongly depends on the spin exchange energy instead. Concurrent measurements of the spin correlations reveal a dynamical dressing of the hole by its spin environment, hinting at the formation and spreading of a magnetic polaron. This work enables the study of out-of-equilibrium emergent phenomena in the Fermi-Hubbard model, one dopant at a time.