Dichotomy of the hydrogen atom in superintense, high-frequency laser fields.

We study the behavior of atomic hydrogen in a monochromatic radiation field of high frequency $\ensuremath{\omega}$ and high intensity $I$, when its structure depends only on the parameter ${\ensuremath{\alpha}}_{0}={I}^{\frac{1}{2}}{\ensuremath{\omega}}^{\ensuremath{-}2}$ a.u., and when multiphoton ionization is quenched. At large ${\ensuremath{\alpha}}_{0}$ the ground-state binding energy undergoes a drastic reduction. This is coupled to an unprecedented stretching of the (oscillating) electron wave function, culminating in its separation into two parts (dichotomy) for ${\ensuremath{\alpha}}_{0}g50$ a.u.