Séminaire

Vendredi 15 Septembre 2023 à 11h00.

Emergent phenomena in active matter and beyond

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Active matter deals with the study of colloidal systems for which Brownian motion is replaced by a persistent self-propulsion. Such an approach, which has already led to breakthroughs in our understanding of living systems, has recently inspired a new wealth of experiments involving artificial constituents. In these setups, the active entities are synthetic units whose self-propulsion relies on a physical rather than biological mechanism.

In this talk, I will present my work in active matter with a focus on collective behaviors emerging at the macroscopic scale. After a brief quantitative study of a single active particle, I will introduce one of the paradigmatic active many-body phenomena: the transition to collective motion. Focusing first on its characterization, I will show that it generically follows a first order transition. I will then assess how flocking interplays with additional steric repulsions at high density to produce active solidification in roller flocks. Finally, I will study how nonreciprocity impacts collective motion to induce flock localization as well as the emergence of a novel Rest & Chase collective phase.

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