Test of the Additivity Principle for Current Fluctuations in a Model of Heat Conduction

TL;DR

This paper confirms the additivity principle for current fluctuations in a 1D heat conduction model, showing it accurately predicts current distributions and associated temperature profiles across different regimes.

Contribution

The study validates the additivity principle in a 1D heat conduction model through simulations, demonstrating its effectiveness in predicting current fluctuations and profiles.

Findings

Current distribution exhibits Gaussian and non-Gaussian regimes.

Temperature profile is independent of current sign.

Finite-time fluctuations are described by the additivity functional.

Abstract

The additivity principle allows to compute the current distribution in many one-dimensional (1D) nonequilibrium systems. Using simulations, we confirm this conjecture in the 1D Kipnis-Marchioro-Presutti model of heat conduction for a wide current interval. The current distribution shows both Gaussian and non-Gaussian regimes, and obeys the Gallavotti-Cohen fluctuation theorem. We verify the existence of a well-defined temperature profile associated to a given current fluctuation. This profile is independent of the sign of the current, and this symmetry extends to higher-order profiles and spatial correlations. We also show that finite-time joint fluctuations of the current and the profile are described by the additivity functional. These results suggest the additivity hypothesis as a general and powerful tool to compute current distributions in many nonequilibrium systems.