Strong-field atomic physics in the x-ray regime

The advent of x-rays sources with unprecedented intensity will enable the study of nonlinear physics in the high frequency regime. In 2009, a physicist dream became reality with the commissioning of the world’s first x-ray free-electron laser, the LCLS, at SLAC. In contrast to low frequency strong-field physics where valence electrons react to the optical field, at high frequency the atom will be ionized from the inside out. The question remains as to whether the atomic response to x-rays will be adequately described by low-order perturbation theory or necessitate a non-perturbative description which is more commonly used at low-frequency. In this talk, these issues will be raised along with the basics of x-ray free-electron laser operation and initial experiments performed at the LCLS.