title: Disorder-mediated crowd control in an active matter system.
abstract: Living active matter systems such as bacterial colonies, schools of fish and human crowds, display a wealth of emerging collective and dynamic behaviours as a result of far-from-equilibrium interactions. The dynamics of these systems are better understood and controlled considering their interaction with the environment, which for realistic systems is often highly heterogeneous and disordered. Here, we demonstrate that the presence of spatial disorder can alter the long-term dynamics in a colloidal active matter system, making it switch between gathering and dispersal of individuals. At equilibrium, colloidal particles always gather at the bottom of any attractive potential; however, under non-equilibrium driving forces in a bacterial bath, the colloids disperse if disorder is added to the potential. The depth of the local roughness in the environment regulates the transition between gathering and dispersal of individuals in the active matter system, thus inspiring novel routes for controlling emerging behaviours far from equilibrium.
authors.affiliation: Department of Physics, Bilkent University, Çankaya, 06800 Ankara, Turkey.
authors.forename: Erçağ
authors.initials: E
authors.lastname: Pinçe
authors.affiliation: Department of Physics, Bilkent University, Çankaya, 06800 Ankara, Turkey.
authors.forename: Sabareesh K P
authors.initials: SK
authors.lastname: Velu
authors.affiliation: Department of Physics, Bilkent University, Çankaya, 06800 Ankara, Turkey.
authors.forename: Agnese
authors.initials: A
authors.lastname: Callegari
authors.affiliation: Department of Physics, Bilkent University, Çankaya, 06800 Ankara, Turkey.
authors.forename: Parviz
authors.initials: P
authors.lastname: Elahi
authors.affiliation: Laboratoire Kastler Brossel, Université Pierre et Marie Curie, École Normale Supérieure, CNRS, College de France, 24 rue Lhomond, 75005 Paris, France.
authors.forename: Sylvain
authors.identifier: http://orcid.org/0000-0002-9914-6231
authors.initials: S
authors.lastname: Gigan
authors.affiliation: Department of Physics, Bilkent University, Çankaya, 06800 Ankara, Turkey.|UNAM-National Nanotechnology Research Center, Bilkent University, Çankaya, 06800 Ankara, Turkey.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Volpe
authors.affiliation: Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, UK.
authors.forename: Giorgio
authors.initials: G
authors.lastname: Volpe
mesh_terms: D003102:Colloids / Q000737:chemistry; D017753:Ecosystem; D004926:Escherichia coli / Q000737:chemistry* / Q000254:growth & development*; D008954:Models, Biological; D013696:Temperature
chemical_list: D003102:Colloids