Observation of Nagaoka polarons in a Fermi–Hubbard quantum simulator

Publication Date

5-9-2024

Document Type

Article

Publication Title

Nature

Volume

629

Issue

8011

DOI

10.1038/s41586-024-07272-9

First Page

317

Last Page

322

Abstract

Quantum interference can deeply alter the nature of many-body phases of matter1. In the case of the Hubbard model, Nagaoka proved that introducing a single itinerant charge can transform a paramagnetic insulator into a ferromagnet through path interference2–4. However, a microscopic observation of this kinetic magnetism induced by individually imaged dopants has been so far elusive. Here we demonstrate the emergence of Nagaoka polarons in a Hubbard system realized with strongly interacting fermions in a triangular optical lattice5,6. Using quantum gas microscopy, we image these polarons as extended ferromagnetic bubbles around particle dopants arising from the local interplay of coherent dopant motion and spin exchange. By contrast, kinetic frustration due to the triangular geometry promotes antiferromagnetic polarons around hole dopants7. Our work augurs the exploration of exotic quantum phases driven by charge motion in strongly correlated systems and over sizes that are challenging for numerical simulation8–10.

Funding Number

GBMF-11521

Funding Sponsor

Generalitat de Catalunya

Department

Physics and Astronomy

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