title: Long-range nematic order and anomalous fluctuations in suspensions of swimming filamentous bacteria.
abstract: We study the collective dynamics of elongated swimmers in a very thin fluid layer by devising long filamentous nontumbling bacteria. The strong confinement induces weak nematic alignment upon collision, which, for large enough density of cells, gives rise to global nematic order. This homogeneous but fluctuating phase, observed on the largest experimentally accessible scale of millimeters, exhibits the properties predicted by standard models for flocking, such as the Vicsek-style model of polar particles with nematic alignment: true long-range nematic order and nontrivial giant number fluctuations.
authors.affiliation: Department of Physics, The University of Tokyo, Hongo 7-3-1, Tokyo 113-0033, Japan.
authors.forename: Daiki
authors.initials: D
authors.lastname: Nishiguchi
authors.affiliation: School of Materials Science, Japan Advanced Institute of Science and Technology, Ishikawa 923-1292, Japan.
authors.forename: Ken H
authors.initials: KH
authors.lastname: Nagai
authors.affiliation: Service de Physique de l'Etat Condensé, CEA, CNRS, Université Paris-Saclay, CEA-Saclay, 91191 Gif-sur-Yvette, France.|Beijing Computational Science Research Center, Beijing 100094, China.
authors.forename: Hugues
authors.initials: H
authors.lastname: Chaté
authors.affiliation: Department of Physics, The University of Tokyo, Hongo 7-3-1, Tokyo 113-0033, Japan.
authors.forename: Masaki
authors.initials: M
authors.lastname: Sano
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D018407:Bacterial Physiological Phenomena; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D002506:Cephalexin / Q000494:pharmacology; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D008856:Microscopy, Fluorescence; D008954:Models, Biological; D009068:Movement; D014741:Video Recording
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D008164:Luminescent Proteins; C054562:yellow fluorescent protein, Bacteria; D002506:Cephalexin