CCB Colloquium: Ramin Golestanian

Date & Time

Ramin Golestanian, Ph.D.
Max Planck Institute for Dynamics and Self-Organization in Göttingen and
Oxford University

Title: A classical analogue of Bose-Einstein condensation in active matter

Abstract: Nonequilibrium statistical physics of dense active matter is a fascinating and rich playground in which a variety of emergent behavior is observed. A natural consequence of the high density in the system will be that the active elements will strongly interact with each giving rise to enhancement and inhibition in their collective activity. This nonequilibrium interaction should ultimately give rise to a dynamic arrest at sufficiently high densities, which yields a diffusivity edge. This effect has so far been neglected in all contributions in the literature of dense active matter. In my talk, I will show how one can build on the recent surge in developing generalized thermodynamic descriptions for scalar active matter, and formulate a generic theoretical description for a large class of active matter systems, which can be described by a density field, and incorporated the notion of a diffusivity edge for the first time. This is a density threshold beyond which the effective (density-dependent) diffusivity of the system vanishes. The model can be solved exactly for the stationary-state behavior of the system – which has been the subject of recent intense investigations – despite being highly singular. The exact solution shows a remarkable emergent feature in the system; a dynamical phase transition that is formally equivalent to Bose-Einstein condensation, despite the system being intrinsically classical. I discuss the relevant generalized thermodynamic properties of the system, and demonstrate how signatures of such behavior can be sought in experiments.

About the Speaker

Ramin Golestanian obtained his BSc from Sharif University of Technology in Tehran, and his MSc and PhD from the Institute for Advanced Studies in Basic Sciences (IASBS) in Zanjan. His PhD work was conducted under the remote supervision of Mehran Kardar from MIT, and was followed by an independent postdoctoral research fellowship at the Kavli Institute for Theoretical Physics at the University of California at Santa Barbara. He has held academic positions at IASBS, the University of Sheffield, and Oxford University, and risen through the ranks until he became a Full Professor in 2007. He has a broad interest in various aspects of nonequilibrium statistical physics, soft matter, and biological physics. Golestanian is distinguished for his work on active matter, and in particular, for his role in developing microscopic swimmers and active colloids.

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