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arXiv · 2308.04148

Stochastic energetics of a colloidal particle trapped in a viscoelastic bath

Farshad Darabi·Brandon R. Ferrer·Juan Ruben Gomez-Solano
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Abstract

We investigate the statistics of the fluctuations of the energy transfer between an overdamped Brownian particle, whose motion is confined by a stationary harmonic potential, and a surrounding viscoelastic fluid at constant temperature. We derive an analytical expression for the probability density function of the energy exchanged with the fluid over a finite time interval, which implicitly involves the friction memory kernel that encodes the coupling with such a non-Markovian environment, and reduces to the well known expression for the heat distribution in a viscous fluid. We show that, while the odd moments of this distribution are zero, the even moments can be explicitly expressed in terms of the auto-correlation function of the particle position, which generally exhibits a non-mono-exponential decay when the fluid bath is viscoelastic. Our results are verified by experimental measurements for an optically-trapped colloidal bead in semidilute micellar and polymer solutions, finding and excellent agreement for all time intervals over which the energy exchange takes place.

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Farshad Darabi, Brandon R. Ferrer, Juan Ruben Gomez-Solano. 2023-08-08. Stochastic energetics of a colloidal particle trapped in a viscoelastic bath. https://doi.org/10.1088/1367-2630/acffed

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