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arXiv · 1712.01733

Probing the Fluctuation-Dissipation Theorem in a Perrin-like Experiment

Jean Colombani·Laure Petit·Christophe Ybert·Catherine Barentin
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Abstract

In this Letter, we present a new experimental approach to investigate the effective temperature concept as a generalization of the fluctuation-dissipation theorem (FDT) for nonequilibrium systems. Simultaneous measurements of diffusion coefficient and sedimentation velocity of heavy colloids, embedded in a Laponite clay suspension, are performed with a fluorescence-recovery-based setup. This nonperturbative dual measurement, performed at a single time in a single sample, allows for a direct application of the FDT to the tracer velocity observable. It thus provides a well-defined derivation of the effective temperature in this ageing colloidal gel. For a wide range of concentrations and ageing times, we report no violation of the FDT, with effective temperature agreeing with bath temperature. This result is consistent with recent theoretical predictions on the coupling between the velocity observable and nonequilibrium gels dynamics.

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Jean Colombani, Laure Petit, Christophe Ybert, Catherine Barentin. 2017-12-05. Probing the Fluctuation-Dissipation Theorem in a Perrin-like Experiment. https://doi.org/10.1103/physrevlett.107.130601

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