Ballistic resonance and thermalization in Fermi-Pasta-Ulam-Tsingou chain at finite temperature

TL;DR

This paper investigates how thermal energy converts to mechanical vibrations in a FPUT chain at finite temperature, revealing a new ballistic resonance phenomenon that suppresses the classical recurrence paradox.

Contribution

It introduces the concept of ballistic resonance in FPUT chains at finite temperature and analytically demonstrates its role in energy conversion and recurrence suppression.

Findings

Identification of ballistic resonance phenomenon

Analytical demonstration of energy transfer mechanisms

Elimination of FPUT recurrence at finite temperature

Abstract

We study conversion of thermal energy to mechanical energy and vice versa in $\alpha$-Fermi-Pasta-Ulam-Tsingou~(FPUT) chain with spatially sinusoidal profile of initial temperature. We show analytically that coupling between macroscopic dynamics and quasiballistic heat transport gives rise to mechanical vibrations with growing amplitude. This new phenomenon is referred to as "ballistic resonance". At large times, these mechanical vibrations decay monotonically, and therefore the well-known FPUT recurrence paradox occurring at zero temperature is eliminated at finite temperatures.