title: Observation of spatial charge and spin correlations in the 2D Fermi-Hubbard model.
abstract: Strong electron correlations lie at the origin of high-temperature superconductivity. Its essence is believed to be captured by the Fermi-Hubbard model of repulsively interacting fermions on a lattice. Here we report on the site-resolved observation of charge and spin correlations in the two-dimensional (2D) Fermi-Hubbard model realized with ultracold atoms. Antiferromagnetic spin correlations are maximal at half-filling and weaken monotonically upon doping. At large doping, nearest-neighbor correlations between singly charged sites are negative, revealing the formation of a correlation hole, the suppressed probability of finding two fermions near each other. As the doping is reduced, the correlations become positive, signaling strong bunching of doublons and holes, in agreement with numerical calculations. The dynamics of the doublon-hole correlations should play an important role for transport in the Fermi-Hubbard model.
authors.affiliation: Department of Physics, MIT-Harvard Center for Ultracold Atoms, and Research Laboratory of Electronics, Massachusetts Institute of Technology (MIT), Cambridge, MA 02139, USA.
authors.forename: Lawrence W
authors.initials: LW
authors.lastname: Cheuk
authors.affiliation: Department of Physics, MIT-Harvard Center for Ultracold Atoms, and Research Laboratory of Electronics, Massachusetts Institute of Technology (MIT), Cambridge, MA 02139, USA.
authors.forename: Matthew A
authors.initials: MA
authors.lastname: Nichols
authors.affiliation: Department of Physics, MIT-Harvard Center for Ultracold Atoms, and Research Laboratory of Electronics, Massachusetts Institute of Technology (MIT), Cambridge, MA 02139, USA.
authors.forename: Katherine R
authors.initials: KR
authors.lastname: Lawrence
authors.affiliation: Department of Physics, MIT-Harvard Center for Ultracold Atoms, and Research Laboratory of Electronics, Massachusetts Institute of Technology (MIT), Cambridge, MA 02139, USA.
authors.forename: Melih
authors.initials: M
authors.lastname: Okan
authors.affiliation: Department of Physics, MIT-Harvard Center for Ultracold Atoms, and Research Laboratory of Electronics, Massachusetts Institute of Technology (MIT), Cambridge, MA 02139, USA.
authors.forename: Hao
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Department of Physics and Astronomy, San José State University, San José, CA 95192, USA.
authors.forename: Ehsan
authors.initials: E
authors.lastname: Khatami
authors.affiliation: Department of Physics, The Ohio State University, Columbus, OH 43210, USA.
authors.forename: Nandini
authors.initials: N
authors.lastname: Trivedi
authors.affiliation: Instituto de Fisica, Universidade Federal do Rio de Janeiro, Caixa Postal 68.528, 21941-972 Rio de Janeiro, RJ, Brazil.
authors.forename: Thereza
authors.initials: T
authors.lastname: Paiva
authors.affiliation: Department of Physics, The Pennsylvania State University, University Park, PA 16802, USA.
authors.forename: Marcos
authors.initials: M
authors.lastname: Rigol
authors.affiliation: Department of Physics, MIT-Harvard Center for Ultracold Atoms, and Research Laboratory of Electronics, Massachusetts Institute of Technology (MIT), Cambridge, MA 02139, USA. zwierlein@mit.edu.
authors.forename: Martin W
authors.initials: MW
authors.lastname: Zwierlein