Non-Markovian heat production in ultrafast phonon dynamics

TL;DR

This paper develops a microscopic framework to understand non-Markovian phonon dynamics under ultrafast laser excitation, revealing how memory effects influence heat production and enabling experimental measurement of thermodynamic quantities.

Contribution

It introduces a method to reconstruct noise and dissipation kernels from molecular dynamics, linking microscopic phonon behavior to macroscopic heat production in non-Markovian regimes.

Findings

Quantifies the crossover between Markovian and non-Markovian phonon dynamics.

Shows how finite laser bandwidth limits bath spectrum relevance.

Demonstrates thermodynamic quantities can be inferred from single phonon mode dynamics.

Abstract

High-intensity THz laser pulses enable the light-mediated control of lattice vibrations by resonantly driving selected phonon modes. On ultrafast timescales, memory effects influence the phonon dynamics and must be accounted for to describe the heat production associated with energy dissipation. Here, we establish a microscopic framework for non-Markovian phonon dynamics by deriving the noise and dissipation kernels governing a driven phonon mode. Using large-scale molecular dynamics simulations, we reconstruct these kernels directly from the many-body lattice dynamics and determine the corresponding heat production rate. Our results provide a quantitative picture of the crossover between Markovian and non-Markovian dynamics on picosecond timescales and show how the finite bandwidth of the driving field limits the dynamically relevant bath spectrum. Furthermore, we demonstrate that thermodynamic quantities such as heat production can be inferred directly from the dynamics of an individual phonon mode, enabling their experimental measurement using time-resolved spectroscopy.