Collective order reorganizes dissipation and powers an active engine

Michael Riedl; Vincent Wattiez; Étienne Fodor; Jan Brugués; Francesco Romanò

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arXiv · 2609.31059

Collective order reorganizes dissipation and powers an active engine

Michael Riedl·Vincent Wattiez·Étienne Fodor·Jan Brugués·Francesco Romanò

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Abstract

Motile active matter systems, from animal groups to synthetic particles, exhibit spontaneous self-organized transitions between disordered and ordered collective states. These transitions are driven by continuous energy injection, yet how energy consumption and dissipation change during these transitions remains poorly understood due to the challenge of measuring individual energetic fluxes. Here, we introduce a minimal experimental system of synthetic motile spheres that enables the first time-resolved power-budget characterization of collective motion. We show that the transition to an ordered state is accompanied by increased locomotion efficiency and a reorganization of dissipation pathways, shifting dissipation from internal friction to external slip with the environment. Leveraging this energetic reorganization, we construct an active engine powered by collective motion, capable of performing mechanical work against an external load. These findings establish energetic fluxes as quantitative observables for understanding collective state transitions and demonstrate how collective order can be harnessed for work extraction in active matter.

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Michael Riedl, Vincent Wattiez, Étienne Fodor, Jan Brugués, Francesco Romanò. 2026-09-25. Collective order reorganizes dissipation and powers an active engine. https://arxiv.org/abs/2609.31059

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