Unbiased description of magnetic polarons in a Mott insulator

Polarons are elementary quasi-particles characterizing several interacting many-body quantum systems. The authors present an unbiased Quantum Monte Carlo simulation of a magnetic polaron in a t-J model at low-temperature, and find excellent agreement with a recent experimental realization in the framework of cold-atoms systems. Polarons are among the most elementary quasiparticles of interacting quantum matter, consisting of a charge carrier dressed by an excited background. In Mott insulators, they take the form of a dopant surrounded by a distorted spin-background. Despite the fundamental importance of polarons for the electronic structure of strongly correlated systems, access to their internal structure was only recently realized in experiments, while controllable theoretical results are still lacking due to the sign problem. Here we report unbiased high-precision data obtained from worm-algorithm Monte Carlo that reveal the real-space structure of a polaron in thet-Jmodel deep inside the region where the sign problem becomes significant. These results are directly comparable to recent quantum gas microscopy experiments, but give access to significantly lower temperatures.