2020/05/31 by Suropriya Saha, Jaime Agudo-Canalejo, Ramin Golestanian · 2 citations
Physics and Astronomy · #cond-mat.stat-mech #cond-mat.soft #physics.bio-ph #physics.chem-ph
paper · pdf · doi:10.1103/physrevx.10.041009
published as Phys. Rev. X 10, 041009 (2020) · Revised version, to appear in Phys. Rev. X
arxiv created 2020/09/01 · arxiv updated 2020/10/21
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 non-reciprocal 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 multi-component mixture with microscopic non-reciprocal interactions.