Fluctuations in an aging system: absence of effective temperature in the sol-gel transition of a quenched gelatin sample

Antoine Bérut; Artyom Petrosyan; Juan Ruben Gomez-Solano; Sergio Ciliberto

doi:10.1088/1742-5468/2015/10/p10020

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arXiv · 1509.01055

Fluctuations in an aging system: absence of effective temperature in the sol-gel transition of a quenched gelatin sample

Antoine Bérut·Artyom Petrosyan·Juan Ruben Gomez-Solano·Sergio Ciliberto

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Abstract

We study the fluctuations of a Brownian micro particle trapped with optical tweezers in a gelatin solution undergoing a fast local temperature quench below the sol-gel transition. Contrary to what was previously reported, we observe no anomalous fluctuations in the particle's position that could be interpreted in terms of an effective temperature. A careful analysis with ensemble averages shows only equilibrium-like properties for the fluctuations, even though the system is clearly aging. We also provide a detailed discussion on possible artifacts that could have been interpreted as an effective temperature, such as the presence of a drift or a mixing in time and ensemble averages in data analysis. These considerations are of general interest when dealing with non-ergodic or non-stationary systems.

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Antoine Bérut, Artyom Petrosyan, Juan Ruben Gomez-Solano, Sergio Ciliberto. 2015-09-03. Fluctuations in an aging system: absence of effective temperature in the sol-gel transition of a quenched gelatin sample. https://doi.org/10.1088/1742-5468/2015/10/p10020

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