Over the past decade, a new generation of light sources known as X-ray free-electron lasers (XFELs) has transformed our ability to explore matter under extreme conditions. These machines produce ultra-bright, ultrashort X-ray pulses (lasting just femtoseconds) that allow us to observe atomic-scale processes as they unfold in real time. By combining XFELs with powerful optical lasers, we can recreate and probe environments similar to those found deep inside planets, in stellar interiors, and in high-energy plasmas relevant to fusion energy.
In this talk, I will introduce the basic ideas behind XFELs and show how they are used to “light up” matter at extreme temperatures and pressures. We will explore how these tools are helping answer fundamental questions about the behaviour of matter far from everyday conditions, from the structure of dense plasmas to the physics of materials under shock at pressures of millions of atmospheres. Along the way, I will highlight how experiments in this field connect to big challenges such as clean energy and our understanding of the universe.
Finally, I will discuss how this rapidly evolving area of science opens up exciting opportunities for students and early-career researchers, combining ideas from physics, computation, and data science. XFEL science sits at the intersection of disciplines, offering a unique playground for those interested in both fundamental discovery and real-world impact.
Oxford University Physics Society 