title: Anomalous dynamics of intruders in a crowded environment of mobile obstacles.
abstract: Many natural and industrial processes rely on constrained transport, such as proteins moving through cells, particles confined in nanocomposite materials or gels, individuals in highly dense collectives and vehicular traffic conditions. These are examples of motion through crowded environments, in which the host matrix may retain some glass-like dynamics. Here we investigate constrained transport in a colloidal model system, in which dilute small spheres move in a slowly rearranging, glassy matrix of large spheres. Using confocal differential dynamic microscopy and simulations, here we discover a critical size asymmetry, at which anomalous collective transport of the small particles appears, manifested as a logarithmic decay of the density autocorrelation functions. We demonstrate that the matrix mobility is central for the observed anomalous behaviour. These results, crucially depending on size-induced dynamic asymmetry, are of relevance for a wide range of phenomena ranging from glassy systems to cell biology.
authors.affiliation: Condensed Matter Physics Laboratory, Heinrich Heine University, 40225 Düsseldorf, Germany.
authors.forename: Tatjana
authors.initials: T
authors.lastname: Sentjabrskaja
authors.affiliation: CNR-ISC, Università di Roma 'La Sapienza', Piazzale A. Moro 2, Roma 00185, Italy.|Dipartimento di Fisica, Università di Roma 'La Sapienza', Piazzale A. Moro 2, Roma 00185, Italy.
authors.forename: Emanuela
authors.identifier: http://orcid.org/0000-0003-0032-8906
authors.initials: E
authors.lastname: Zaccarelli
authors.affiliation: CNR-ISC, Università di Roma 'La Sapienza', Piazzale A. Moro 2, Roma 00185, Italy.|Dipartimento di Fisica, Università di Roma 'La Sapienza', Piazzale A. Moro 2, Roma 00185, Italy.
authors.forename: Cristiano
authors.initials: C
authors.lastname: De Michele
authors.affiliation: CNR-ISC, Università di Roma 'La Sapienza', Piazzale A. Moro 2, Roma 00185, Italy.|Dipartimento di Fisica, Università di Roma 'La Sapienza', Piazzale A. Moro 2, Roma 00185, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Sciortino
authors.affiliation: Dipartimento di Fisica, Università di Roma 'La Sapienza', Piazzale A. Moro 2, Roma 00185, Italy.
authors.forename: Piero
authors.initials: P
authors.lastname: Tartaglia
authors.affiliation: Institut für Materialphysik im Weltraum, Deutsches Zentrum für Luft- und Raumfahrt (DLR), 51170 Köln, Germany.|Heinrich Heine University, Universitätsstraße 1, 40225 Düsseldorf, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Voigtmann
authors.affiliation: Condensed Matter Physics Laboratory, Heinrich Heine University, 40225 Düsseldorf, Germany.
authors.forename: Stefan U
authors.initials: SU
authors.lastname: Egelhaaf
authors.affiliation: Condensed Matter Physics Laboratory, Heinrich Heine University, 40225 Düsseldorf, Germany.|División de Ciencias e Ingeniería, Universidad de Guanajuato, Loma del Bosque 103, León 37150, Mexico.
authors.forename: Marco
authors.identifier: http://orcid.org/0000-0003-1334-5940
authors.initials: M
authors.lastname: Laurati