Electron-phonon thermalization in a scalable method for real-time quantum dynamics

TL;DR

This paper introduces a scalable quantum simulation method for real-time dynamics of electrons and phonons, capable of modeling thermalization processes over a wide range of timescales in out-of-equilibrium systems.

Contribution

The method efficiently simulates out-of-equilibrium electron-phonon dynamics with linear cost and can model thermalization from diverse initial conditions, unlike traditional Ehrenfest dynamics.

Findings

The method can simulate timescales from attoseconds to hundreds of picoseconds.

It can model thermalization starting from electronic population inversion.

A kinetic model explains the evolution of electronic populations.

Abstract

We present a quantum simulation method that follows the dynamics of out-of-equilibrium many-body systems of electrons and oscillators in real time. Its cost is linear in the number of oscillators and it can probe timescales from attoseconds to hundreds of picoseconds. Contrary to Ehrenfest dynamics, it can thermalize starting from a variety of initial conditions, including electronic population inversion. While an electronic temperature can be defined in terms of a non-equilibrium entropy, a Fermi-Dirac distribution in general emerges only after thermalization. The time evolution of the populations is rationalized in terms of a kinetic model.