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arXiv · 2010.02356

Breakdown of Ergodicity and Self-Averaging in Polar Flocks with Quenched Disorder

Yu Duan·Benoît Mahault·Yu-qiang Ma·Xia-qing Shi·Hugues Chaté
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Abstract

We show that spatial quenched disorder affects polar active matter in ways more complex and far-reaching than believed heretofore. Using simulations of the 2D Vicsek model subjected to random couplings or a disordered scattering field, we find in particular that ergodicity is lost in the ordered phase, the nature of which we show to depend qualitatively on the type of quenched disorder: for random couplings, it remains long-range ordered, but qualitatively different from the pure (disorderless) case. For random scatterers, polar order varies with system size but we find strong non-self-averaging, with sample-to-sample fluctuations dominating asymptotically, which prevents us from elucidating the asymptotic status of order.

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Yu Duan, Benoît Mahault, Yu-qiang Ma, Xia-qing Shi, Hugues Chaté. 2020-10-05. Breakdown of Ergodicity and Self-Averaging in Polar Flocks with Quenched Disorder. https://doi.org/10.1103/physrevlett.126.178001

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