Fluctuation-response relation for a nonequilibrium system with resolved Markovian embedding

Rémi Goerlich; Antoine Tartar; Yael Roichman; Igor M Sokolov

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arXiv · 2601.05198

Fluctuation-response relation for a nonequilibrium system with resolved Markovian embedding

Rémi Goerlich·Antoine Tartar·Yael Roichman·Igor M Sokolov

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Abstract

Fluctuation-response relations must be modified to describe nonequilibrium systems with non-Markovian dynamics. Here, we experimentally demonstrate that such relation is quantitatively recovered when the appropriate Markovian embedding of the dynamics is explicitly resolved. Using a colloidal particle optically trapped in a harmonic potential and driven out of equilibrium by a controlled colored noise, we study the response to a perturbation of the stiffness of the confining potential. While the reduced dynamics violates equilibrium fluctuation-response relations, we show that the dynamical response to the stiffness perturbation is fully determined by steady-state correlations involving the exact conjugate observable in the Markovian embedding.

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Rémi Goerlich, Antoine Tartar, Yael Roichman, Igor M Sokolov. 2026-01-08. Fluctuation-response relation for a nonequilibrium system with resolved Markovian embedding. https://arxiv.org/abs/2601.05198

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