Regensburg 2022 – scientific programme
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DY: Fachverband Dynamik und Statistische Physik
DY 3: Statistical Physics far from Thermal Equilibrium
DY 3.8: Talk
Monday, September 5, 2022, 12:00–12:15, H18
Scalar Active Mixtures: The Nonreciprocal Cahn-Hilliard Model — •Suropriya Saha1, Jaime Agudo-Canalejo1, and Ramin Golestanian1,2 — 1Department of Living Matter Physics, Max Planck Institute for Dynamics and Self-Organization — 2Rudolf Peierls Centre for Theoretical Physics, University of Oxford
Pair interactions between active particles need not follow Newton's third law. In this work, we propose a continuum model of pattern formation due to nonreciprocal interaction between multiple species of scalar active matter. The classical Cahn-Hilliard model is minimally modified by supplementing the equilibrium Ginzburg-Landau dynamics with particle-number-conserving currents, which cannot be derived from a free energy, reflecting the microscopic departure from action-reaction symmetry. The strength of the asymmetry in the interaction determines whether the steady state exhibits a macroscopic phase separation or a traveling density wave displaying global polar order. The latter structure, which is equivalent to an active self- propelled smectic phase, coarsens via annihilation of defects, whereas the former structure undergoes Ostwald ripening. The emergence of traveling density waves, which is a clear signature of broken time- reversal symmetry in this active system, is a generic feature of any multicomponent mixture with microscopic nonreciprocal interactions.