Decomposition of force fluctuations far from equilibrium

TL;DR

This paper investigates force fluctuations in nonequilibrium Langevin systems, deriving a universal inequality and a decomposition framework that could apply broadly to systems far from equilibrium.

Contribution

It introduces a simple condition for force decomposition and derives a new universal inequality relating key physical quantities in nonequilibrium systems.

Findings

Derived a universal inequality: D ≥ γ μ_d^2 T

Proposed a decomposition of force into dissipative, driving, and noise components

Applicable to a wide class of far-from-equilibrium systems

Abstract

By studying a nonequilibrium Langevin system, we find that a simple condition determines the decomposition of the coarse-grained force into a dissipative force, an effective driving force and noise. From this condition, we derive a new universal inequality, $D \ge \gamma \mud^2 T$, relating the diffusion constant $D$, the differential mobility $\mud$, the bare friction constant $\gamma$ and the temperature $T$. Due to the general nature of the argument we present, we believe that our idea concerning this decomposition can be applied to a wide class of systems far from equilibrium.