Nonequilibrium Dynamics in Cuprate Superconductors using Transient Grating Spectroscopy

Transient grating spectroscopy is an excellent method for probing the dynamics of quasiparticles in high-temperature superconductors, which are key to understanding the mechanism behind superconductivity in such materials. Femtosecond optical pulses provide timeresolved measurements of reflectivity. When combined with nonuniform excitation due to the diffraction grating, this technique can effectively separate diffusive quasiparticle dynamics from recombination. The Rothwarf-Taylor (RT) equations have, thus far, provided a successful framework to numerically analyze and understand transient grating measurements. However, most analyses rely on simplifications that result in analytic solutions, such as simple bimolecular recombination. Here, we directly numerically fit pump probe data to the RT equations and attempted to directly fit transient grating data to a generalization of the RT equations that included diffusion.