Modeling strong-field laser-atom interactions with nonlocal potentials

Abstract

Atom-field interactions in the ionization regime give rise to a wide range of physical phenomena, and their study continues to be an active field of research. However, simulation of atom-field dynamics is time-consuming and computationally expensive. In this thesis, a nonlocal model potential is used in place of the Coulomb potential in the time dependent Schrodinger equation, and examined for suitabil- ity of modeling strong field-atom dynamics while offering significant reduction in computation cost. Nonlocal potentials have been used to model many physical systems, from multi-electron molecular configurations to semiconductor theory. Despite their rel- ative success, nonlocal potentials have been largely unexplored for modeling high field laser-gas interactions in the ionizing regime. This work explores the theory and numerical results of a single state gaussian nonlocal model in intense, femtosecond laser pulses, with the main findings: nonlocal potentials are useful for obtaining the photoionization rate in the tunnel and multiphoton regimes, and qualitatively char- acterize the wavefunction dynamics of irradiated atoms. The model is also examined in the context of the two-color technique for producing Terahertz (THz) frequency radiation.