On the propagation of a perturbation in an anharmonic system

TL;DR

This paper establishes an upper bound on how fast disturbances spread in an infinite anharmonic system at thermal equilibrium, using advanced control of non-equilibrium dynamics and state invariance properties.

Contribution

It provides a novel upper bound on disturbance propagation velocity in anharmonic systems, combining control of non-equilibrium dynamics with invariance principles.

Findings

Derived a non-trivial upper bound on disturbance velocity

Utilized control of non-equilibrium dynamics in the proof

Applied state invariance to establish the bound

Abstract

We give a not trivial upper bound on the velocity of disturbances in an infinitely extended anharmonic system at thermal equilibrium. The proof is achieved by combining a control on the non equilibrium dynamics with an explicit use of the state invariance with respect to the time evolution.