By coherently upconverting light from a tabletop-scale femtosecond laser to much shorter wavelengths, it is possible to implement a device that for the first time provides researchers a tabletop “x-ray laser” light source. The high-order harmonic generation (HHG) process used for this represents new physics first observed in the late 1980’s, and whose ultimate implications and limits are still being explored. The unique temporal and spatial coherence characteristics of the light provide fundamentally new capabilities in x-ray science, but also often require development of new experimental approaches.

This decade has seen continued advance in fundamental understanding and capabilities, allowing these new sources to be used for discovery science in a variety of areas, and most-recently attracting interest for possible use in industrial process metrology. In my talk, I will present an overview of the state of the art, as well as examples of experimental applications from our group. Recent examples include observing the dynamics of the quantum exchange interaction fundamental to magnetic materials; the use of coherent HHG light for tabletop nanoimaging with record resolution; and studies of the physical limits of energy flow at the nanoscale. Recent work has also demonstrated that HHG light with circular polarization can be efficiently generated, making possible femtosecond-time-scale studies using X-ray magnetic circular dichroism (XMCD).

Argonne Physics Division Colloquium Schedule