Dresden 2026 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 27: Statistical Physics far from Thermal Equilibrium II

DY 27.1: Talk

Tuesday, March 10, 2026, 14:00–14:15, ZEU/0114

Efficiency of Carnot-like engine for intracellular diffusivity fluctuations and diffusing diffusivity — •Yuichi Itto — Aichi Institute of Technology, Japan — ICP, Universität Stuttgart, Germany

In contemporary physics of intracellular diffusion, much attention is paid to understanding how environmental conditions affect the diffusivity [1], the change of which is crucial, e.g., for tuning the rates of biochemical reactions. Recently, the heat-like engine for local diffusivity fluctuations, which slowly vary and obey a universal exponential law, has been constructed to extract the diffusivity change in a cycle realized by compression/expansion of cells and temperature change [2]: it has the Carnot-like efficiency determined by the average diffusivity.

Here, the effect of slowly varying fluctuation on the efficiency [3] is discussed based on ``diffusing diffusivity'' [4] that describes the dynamics of the fluctuation distribution by an advection-diffusion equation, the stationary solution of which is of the exponential type. The entropy of the fluctuations, which gives the exponential law at its maximum, takes positive production rate under the dynamics. The tendency to approach the (stationary) average diffusivity is dominantly governed by the factor characterizing the diffusion term in its square root, showing its peculiar role in view of the fact that the exponential law is due to the advection term.

References [1] N. Bellotto, J. Agudo-Canalejo, R. Colin, R. Golestanian, G. Malengo, V. Sourjik, eLife 11, e82654 (2022). [2] Y. Itto, Eur. Phys. J. B 98, 183 (2025). [3] Y. Itto, arXiv:2511.06851 (2025). [4] M. V. Chubynsky, G. W. Slater, Phys. Rev. Lett. 113, 098302 (2014).

Keywords: Efficiency of Carnot-like engine; Intracellular diffusion; Effect of slowly varying diffusivity fluctuations; Diffusing diffusivity