Active pistons extract work by periodic compression alone
Abstract
Active matter is liable to invent protocols that evade the constraints of equilibrium thermodynamics. We put forward active pistons that extract work by periodic compression alone without changing any bulk property of the system. Such pistons necessarily couple the perturbation imposed by an external operator with some degrees of freedom internal to active components. We illustrate this design principle with elastic networks composed of self-aligning motile particles. For slow protocols, self-alignment always overwhelms mechanical friction when the internal activity exceeds a specific threshold controlled by fluctuations. We identify the key response coefficient that helps delineate regimes of work extraction, and reveal that the corresponding phase diagram follows a master curve with re-entrance in terms of noise amplitude. Overall, our active pistons embody a novel design principle with broad implications for building innovative engines far from equilibrium.
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BibTeX
@misc{bernard2026active,
title = {{Active pistons extract work by periodic compression alone}},
author = {Paul Bernard and Euijoon Kwon and Benjamin Buhl and Étienne Fodor and Olivier Dauchot},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.15380},
eprint = {2609.15380},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.15380},
}
RIS
TY - UNPB
TI - Active pistons extract work by periodic compression alone
AU - Paul Bernard
AU - Euijoon Kwon
AU - Benjamin Buhl
AU - Étienne Fodor
AU - Olivier Dauchot
PY - 2026
DA - 2026/09/14
PB - arXiv
DO - 10.48550/arxiv.2609.15380
UR - https://arxiv.org/abs/2609.15380
AB - Active matter is liable to invent protocols that evade the constraints of equilibrium thermodynamics. We put forward active pistons that extract work by periodic compression alone without changing any bulk property of the system. Such pistons necessarily couple the perturbation imposed by an external operator with some degrees of freedom internal to active components. We illustrate this design principle with elastic networks composed of self-aligning motile particles. For slow protocols, self-alignment always overwhelms mechanical friction when the internal activity exceeds a specific threshold controlled by fluctuations. We identify the key response coefficient that helps delineate regimes of work extraction, and reveal that the corresponding phase diagram follows a master curve with re-entrance in terms of noise amplitude. Overall, our active pistons embody a novel design principle with broad implications for building innovative engines far from equilibrium.
ER -