String patterns in the doped Hubbard model

• Published in: Science (American Association for the Advancement of Science) Vol. 365; no. 6450; pp. 251 - 256
• Main Authors: Chiu, Christie S, Ji, Geoffrey, Bohrdt, Annabelle, Xu, Muqing, Knap, Michael, Demler, Eugene, Grusdt, Fabian, Greiner, Markus, Greif, Daniel
• Format: Journal Article
• Language: English
• Published: United States The American Association for the Advancement of Science 19-07-2019
• Subjects: Algorithms; Antiferromagnetism; Computer simulation; Computers; Consistency; Correlation; Fermions; Lattice sites; Lithium; Object recognition; Optical lattices; Pattern analysis; Pattern recognition; Phase diagrams; Strings; Two dimensional models
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.aav3587

Understanding strongly correlated quantum many-body states is one of the most difficult challenges in modern physics. For example, there remain fundamental open questions on the phase diagram of the Hubbard model, which describes strongly correlated electrons in solids. In this work, we realize the Hubbard Hamiltonian and search for specific patterns within the individual images of many realizations of strongly correlated ultracold fermions in an optical lattice. Upon doping a cold-atom antiferromagnet, we find consistency with geometric strings, entities that may explain the relationship between hole motion and spin order, in both pattern-based and conventional observables. Our results demonstrate the potential for pattern recognition to provide key insights into cold-atom quantum many-body systems.