Diffusion For Ensembles of Standard Maps

TL;DR

This paper investigates how different random parameter variation processes and noise affect diffusion in ensembles of standard maps, aiming to develop a statistical theory for mixed phase space systems.

Contribution

It introduces and analyzes two types of random evolution processes for standard maps, exploring their effects on diffusion and fine structure destruction.

Findings

Both processes destroy fine dynamical details.

The process with step-by-step variation is more effective.

Results are relevant for experimental systems with mixed phase space.

Abstract

Two types of random evolution processes are studied for ensembles of the standard map with driving parameter $K$ that determines its degree of stochasticity. For one type of processes the parameter $K$ is chosen at random from a Gaussian distribution and is then kept fixed, while for the other type it varies from step to step. In addition, noise that can be arbitrarily weak is added. The ensemble average and the average over noise of the diffusion coefficient is calculated for both types of processes. These two types of processes are relevant for two types of experimental situations as explained in the paper. Both types of processes destroy fine details of the dynamics, and the second process is found to be more effective in destroying the fine details. We hope that this work is a step in the efforts for developing a statistical theory for systems with mixed phase space (regular in some parts and chaotic in other parts).