Fluctuations in partitioning systems with few degrees of freedom

Abstract

We study the behavior of a moving wall in contact with a particle gas and subjected to an external force. We compare the fluctuations of the system observed in the microcanonical and canonical ensembles, at varying the number of particles. Static and dynamic correlations signal significant differences between the two ensembles. Furthermore, velocity-velocity correlations of the moving wall present a complex two-time relaxation which cannot be reproduced by a standard Langevin-like description. Quite remarkably, increasing the number of gas particles in an elongated geometry, we find a typical timescale, related to the interaction between the partitioning wall and the particles, which grows macroscopically.

arXiv comment10 pages, 12 figures

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• Fourier's Law in a Generalized Piston Model
• Mesoscopic description of the adiabatic piston: kinetic equations and $\mathcal{H}$-theorem
• Extracting work from quantum states of radiation
• Resolving the Debate Between Boltzmann and Gibbs Entropy: Relative Energy Window Eliminates Thermodynamic Inconsistencies and Allows Negative Absolute Temperatures
• Non-equilibrium dynamics of the piston in the Szilard engine
• Multiple scales approach to the Gas-Piston non-equilibrium themodynamics