Towards a Many Body Theory for Fourier Transform Inelastic X-Ray Scattering Experiments in Correlated Materials

In recent years new ultrafast x-ray sources have enabled the probing of materials at previously inaccessible time and length scales, allowing for new insights into phonon populations and dynamics far from equilibrium through direct time domain measurements. As these experiments improve, classical descriptions of phonons, particularly in correlated materials, will be pushed to their limits. With this in mind we seek to develop a fully quantum mechanical, many-body theory for ultrafast pump-probe scattering experiments that accounts for electron-phonon coupling and electronic correlations that can inform and inspire experiments. A new theory could help us gain better insight into exotic nonequilibrium states in correlated materials, superconductivity, as well as lead to a better understanding of charge and heat transport under normal operating conditions in current and new devices.