A Ground State of Strongly Interacting Bosons on an Optical Lattice with an Artificial Gauge Field

We study strongly interacting atoms in an artificial gauge field. We realize the ground state of a Harper-Hofstadter system with ultracold $^{\mathrm{87}}$Rb atoms on an optical lattice by superimposing a running lattice of two Raman beams and adding a magnetic field gradient. With the single-site resolution provided by our quantum gas microscope, we have access to atom number distributions and high-order correlation functions. Our study presents a further step towards optical-lattice experiments investigating topological phases and fractional quantum hall systems.