Our research group studies the dynamics of ultrafast processes in atoms, molecules, solids, and plasmas. We develop advanced technologies (pulsed sources of x-rays, high-speed x-ray detectors, and novel techniques), and we perform experiments at major facilities in the Bay Area and around the world. Currently, we are focusing on understanding the behavior of solids and plasmas that are under extreme conditions of pressure and temperature. We are studying how these materials respond to high stress (up to a billion atmospheres of pressure, or 1 GigaBar) and high temperatures (several million degrees, or hundreds of eV). We measure and control dynamics on the length and time scales of atomic motion (down to nanometers and femtoseconds). A particular area of interest is the “equation of state” of high energy density matter, which means understanding the relationship of pressure, density, and temperature under extreme conditions. Also important are electronic, structural, and thermodynamic properties, such as the relative amount of ionization, the local order, and the thermal conductivity in such matter.

The questions we address are generally fundamental, since we are extending science into novel regimes. The applications of our work range from geophysics (what is the chemistry of materials under pressure?), to materials performance (can we design materials that will perform under extreme conditions?), to fusion energy (can we create plasmas at high enough density and temperature to undergo nuclear burn?), to astrophysics (can we understand the physics of giant planets and stars?).

In a separate area of research, we are helping develop novel methods of high-resolution, chemically-resolved, ultrafast, three-dimensional imaging at the nanoscale, using x-rays, in order to better understand the physics and chemistry of functional materials under more conventional conditions.

Our tools involve advanced x-ray synchrotrons, the world’s highest energy lasers, free-electron x-ray lasers, and tabletop, ultrashort pulse lasers. Our team includes faculty and other scientists from many countries, theorists and experimentalists, as well as postdoctoral, graduate, and undergraduate students.