Transient Dynamics of a Single Hole in a Fermi-Hubbard Quantum Simulator

Understanding the interplay between charge and spin and its effects on transport is a ubiquitous challenge in quantum many-body systems. In the 2D Fermi-Hubbard model, this interplay is thought to give rise to magnetic polarons, whose dynamics may explain emergent properties of quantum materials such as high-temperature superconductivity. Here we use a cold-atom quantum simulator of about 400 sites to directly observe the formation dynamics and subsequent spreading of individual magnetic polarons, by deterministically preparing and releasing single holes in an antiferromagnetic spin background. Site-resolved measurements of the resulting dynamics reveal fast initial delocalization and a dressing of the spin background, indicating polaron formation. At long times we observe dynamics slowed down by the spin exchange time and compatible with a polaronic model with strong density and spin coupling. These results shed light on an iconic yet computationally challenging many-body problem and extend the study of elementary excitations of the Hubbard model far from thermodynamical equilibrium.