Time-resolved X-ray Spectroscopy in One-dimensional Strongly Correlated Systems

In recent years, ultrafast pump-probe spectroscopy has provided insightful information about non-equilibrium dynamics of excitations in materials. In a typical experiment of time-resolved x-ray absorption spectroscopy, the systems are excited by a femtosecond laser pulse (pump pulse) following by an x-ray (probe pulse) after a time delay to measure the absorption spectra of the excited systems. In this talk, we present a theory for time-resolved x-ray absorption spectroscopy in one-dimensional strongly correlated systems. We consider a one-dimensional Hubbard model, and use the time-dependent density matrix renormalization group method to solve the ground state and non-equilibrium dynamics numerically. The core hole created by x-ray is modeled as an additional effective potential and interaction on the core hole site. Our study shows that, when the system is away from the half filling, the spectrum shows side peaks along with the major transitions; while the system moves closed to half filling, the spectrum starts to reveal the charge gap. The response of the x-ray absorption spectroscopy to the strength of Hubbard repulsion, and frequency and intensity of laser pump pulse, has also been studied. LA-UR-17-29749