Meeting the Challenge to Theory

These surprising new effects created a major challenge for theoretical physicists. It's a situation, explains Eberly, where the laser light and the atom's nucleus both exert strong forces on the electron, in a sense competing for it. "For the first time," says Eberly, "we've been required to deal with two strong forces acting at the same time."

The research groups headed by Eberly and Kulander attacked the problem and developed different but similar numerical grid approaches to modeling the new phenomena. For Eberly, the key was recognizing that the laser is so strong that it forces the electron to move back and forth along the line of laser polarization. This insight led his group to try a one-dimensional model, rather than the usual three-dimensional approach to modeling electron movement. "We discovered," says Eberly, "that a one-dimensional model could be remarkably reliable." This is a big advantage computationally since it makes it possible to track wide excursions in electron motion realistically with very efficient use of the computing resources.

Satisfactory results in simulating the laser experiments led the Rochester team to speculate that their computational tool was reliable enough to model even higher laser intensities, 100 to 1,000 times higher than the experiments had reached. "It was gratifying to see," says Eberly, "that theorists were in the position to make discoveries instead of just explaining what the experimentalists were finding."

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