EventOlivier Dauchot

Nonlinear world of commercial photonic systems

The ubiquity of collective motions observed at all scales, ranging from the cooperative action of molecular motors to the behavior of large animal or human groups, has driven a surge of scientific activity. Within physics, important theoretical progress was achieved by studying microscopic point-particles models and their continuous descriptions. Among the landmark results is the possibility of a true long-range polar ordered collective motion as well as of a Motility Induced Phase Separation.

The robustness of these observations against the numerous factors integrated out in the above effective models is a matter of crucial importance towards a reliable description of living systems. The latter however often integrate too many source of complexity, to allow for an immediate comparison.

This is where human-designed model experimental systems have a role to play. Janus colloids, swimming droplets or walking grains are amazing experimental realization of self propelled particles. They are far more simple than their biological inspiration, and already contain important realistic factors, such as hydrodynamics effects and pairwise force interactions, which, at least in principle, can be controlled. In the present talk, I will first illustrate what we have learnt in the past decade about collective dynamics in active systems using such model experimental systems.

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About The Speaker

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Olivier Dauchot is Director of the CNRS Gulliver laboratory, at ESPCI Paris, PSL University, where he has lead the research team EC2M (Collective effects in Soft Matter) between 2011 and 2018. His general interest is to develop model experiments for studying divided soft-matter and collective effects. Developing collaborations with theoretical teams is one of his hallmarks. He presently concentrates on active matter, self-assembling, and glass forming systems.

Previously, Olivier was leading the Group Instabilities and Turbulence in CEA-Saclay. At that time he brought significant contributions to the study of jamming in granular media, to that of chaotic mixing, as well as to the understanding of transition to turbulence, his first research topic.