Parallelizable Algorithms For Describing The Effects Of Strong Time-Dependent Electromagnetic Fields On The Hydrogen Atom

We are testing a variety of methods to numerically treat the ionization of atomic hydrogen by a strong laser pulse. Besides providing high accuracy, the algorithms should be parallelizable in order to handle the sometimes long propagation times needed to solve the time-dependent Schrodinger equation for this fundamental strong-field problem. We report progress on developing a computer code that will make such calculations possible on massively parallel supercomputer platforms. Introduction and Motivation • 1 attosecond is one-millionth of one millionth of one millionth (10−18) of a second. • There are twice as many attoseconds in 1 second than seconds in the age of the universe (15 billion years)! • The period for the n = 1 orbit in atomic hydrogen is about 150 attoseconds. •Attosecond laser pulses provide a window to study the details of (valence) electron interactions in atoms and molecules. •A major role for theory in attosecond science is to suggest novel ways of investigating and controlling electronic processes in matter on ultra-short time scales. • Typical laser intensities in this field range from 1012 to 1015 W/cm2. • 1014 W/cm2 is a million billion times stronger than the radiation that the Earth receives from the Sun directly above us on a clear day. • Such intensities can rip electrons away from atoms in very different ways from the standard photoeffect: –Multi-photon ionization –Above-threshold ionization – Field (tunnel) ionization Single vs. Multi−Photon Ionization in Atomic Hydrogen