Dynamical Evolution in Noncommutative Discrete Phase Space and the Derivation of Classical Kinetic Equations

TL;DR

This paper develops a noncommutative geometric framework for lattice phase space, deriving classical kinetic equations like Fokker-Planck and Kramers' equations from microscopic models, bridging discrete and continuous descriptions.

Contribution

It introduces a novel noncommutative differential geometric approach to lattice phase space, deriving classical kinetic equations from microscopic lattice dynamics.

Findings

Derivation of Fokker-Planck and Smoluchowski equations from lattice models

Extension of Kramers' equation assuming deterministic motion in coordinate space

Application to 1D and 2D systems demonstrating the framework's validity

Abstract

By considering a lattice model of extended phase space, and using techniques of noncommutative differential geometry, we are led to: (a) the conception of vector fields as generators of motion and transition probability distributions on the lattice; (b) the emergence of the time direction on the basis of the encoding of probabilities in the lattice structure; (c) the general prescription for the observables' evolution in analogy with classical dynamics. We show that, in the limit of a continuous description, these results lead to the time evolution of observables in terms of (the adjoint of) generalized Fokker-Planck equations having: (1) a diffusion coefficient given by the limit of the correlation matrix of the lattice coordinates with respect to the probability distribution associated with the generator of motion; (2) a drift term given by the microscopic average of the dynamical equations in the present context. These results are applied to 1D and 2D problems. Specifically, we derive: (I) The equations of diffusion, Smoluchowski and Fokker-Planck in velocity space, thus indicating the way random walk models are incorporated in the present context; (II) Kramers' equation, by further assuming that, motion is deterministic in coordinate space