Quantum theory of light-driven coherent lattice dynamics

TL;DR

This paper develops a comprehensive quantum theoretical framework to describe light-driven coherent lattice dynamics in solids, incorporating various excitation mechanisms and quantum nuclear effects, advancing understanding of ultrafast structural control.

Contribution

It introduces a unified quantum approach to model coherent phonon excitation mechanisms and quantum nuclear effects in lattice dynamics, extending classical models.

Findings

Quantum nuclei influence structural distortions in ionic Raman scattering.

The formalism validates classical models and highlights quantum effects.

Versatile approach for exploring quantum nuclear impacts in lattice responses.

Abstract

The exposure to intense electromagnetic radiation can induce distortions and symmetry breaking in the crystal structure of solids, providing a route for the all-optical control of their properties. In this manuscript, we formulate a unified theoretical approach to describe the coherent lattice dynamics in presence of external driving fields, electron-phonon and phonon-phonon interactions, and quantum nuclear effects. The main mechanisms for the excitation of coherent phonons - including infrared absorption, displacive excitation, inelastic stimulated Raman scattering, and ionic Raman scattering - can be seamlessly accounted for. We apply this formalism to a model consisting of two coupled phonon modes, where we illustrate the influence of quantum nuclei on structural distortions induced by ionic Raman scattering. Besides validating the widely-employed classical models for the coherent lattice dynamics, our work provides a versatile approach to methodically explore the emergence of quantum nuclear effects in the structural response of crystal lattice to strong fields.