Directed motion and useful work from an isotropic nonequilibrium distribution

TL;DR

This paper shows that classical particles in an asymmetric potential with a nonequilibrium velocity distribution can exhibit quasiperiodic motion and generate useful work, functioning as a microscopic engine.

Contribution

It introduces a mechanism where nonequilibrium velocity distributions induce directed motion and work in a classical particle system within an asymmetric potential.

Findings

Particles exhibit quasiperiodic motion when initial velocity distribution is nonequilibrium.

The direction of motion depends on the temperature difference from equilibrium.

The system can operate as a microscopic Carnot engine.

Abstract

We demonstrate that a gas of classical particles trapped in an external asymmetric potential undergoes a quasiperiodic motion, if the temperature of its initial velocity distribution $T_{ne}$ differs from the equilibrium temperature, $T_{eq}$. The magnitude of the effect is determined by the value of $T_{ne}-T_{eq}$, and the direction of the motion is determined by the sign of this expression. The "loading'' and "unloading'' of the gas particles change directions of their motion, thereby creating a possibility of shuttle-like motion. The system works as a Carnot engine where the heat flow between kinetic and potential parts of the nonequilibrium distribution produces the useful work.