https://phys.org/news/2018-06-physicists-method-reveal-affects-materials.html

From solar panels to cameras and cell phones—to seeing with our eyes—the interaction of photons of light with atoms and electrons is ubiquitous. "Optical phenomenon is such a fundamental process that we take it for granted, and yet it's not fully understood how light interacts with materials," Harutyunyan says.

One obstacle to understanding the details of these interactions is their complexity. When the energy of a light photon is transferred to an electron in a light-absorbing material, the photon is destroyed and the electron is excited from one level to another. But so many photons, atoms and electrons are involved—and the process happens so quickly—that laboratory modeling of the process is computationally challenging.