Relaxation dynamics of the Holstein polaron

TL;DR

This paper investigates the relaxation dynamics of the Holstein polaron after excitation, revealing how the relaxation time depends on electron-phonon coupling and aligning with self-energy calculations.

Contribution

It provides a full quantum analysis of the Holstein polaron's relaxation time post-excitation, highlighting the coupling dependence and agreement with self-energy results.

Findings

Inverse relaxation time scales linearly with coupling at small values

Deviation from linearity occurs at higher coupling strengths

Imaginary part of self-energy matches relaxation times from simulations

Abstract

Keeping the full quantum nature of the problem we compute the relaxation time of the Holstein polaron after it was driven far from the equilibrium by a strong oscillatory pulse. Just after the pulse the polaron's kinetic energy increases and subsequently exhibits relaxation type decrease with simultaneous emission of phonons. In the weak coupling regime partial tunneling of the electron from the polaron self-potential is observed. The inverse relaxation time is for small values of electron-phonon coupling $\lambda$ linear with $\lambda$, while it deviates downwards from the linear regime at $\lambda \gtrsim 0.1/\omega_0$. The imaginary part of the equilibrium self energy shows good agreement with the inverse relaxation time obtained from nonequilibrium simulations.