Looking for Patterns in an Optical Lattice

July 23, 2019

Fig. 1 Quantum simulation of the Hubbard model.

One of the simplest models of interacting fermions on a two-dimensional (2D) lattice—the Hubbard model—becomes too tricky to simulate on classical computers as the density of empty lattice sites (holes) increases. Harvard scientists, in partnership with Munich Center for Quantum Science and Technology, Munich, Germany, used a quantum microscope to take snapshots of thousands of realizations of the 2D Hubbard model in an optical lattice filled with fermionic lithium atoms at varying hole densities (see the Perspective by Schauss). They used pattern recognition algorithms to analyze the images, in which each lattice site was individually resolved. Comparing these patterns to the predictions of several theoretical models, they found the most consistency with the so-called geometric string model.

Christie S. Chiu, Geoffrey Ji, Annabelle Bohrdt, Muqing Xu, Michael Knap, Eugene Demler, Fabian Grusdt, Markus Greiner, and Daniel Greif, "String patterns in the doped Hubbard model," Science 365  (2019). https://doi.org/10.1126/science.aav3587