Non-linear and non-local optical response in quantum materials

The optical response of quantum materials under low-intensity illumination is interesting and remains unexplored. Here, we develop a non-linear and non-local model to describe the dielectric function of a wide variety of quantum materials. We apply the model to
$1\mathrm{T}-\text{TaS}_{2}$
, a charge density wave (CDW) material. Our model correctly captures the competition between the CDW stacking phases.