JILA is proud to announce that Dr. Kai Li, a researcher in the Jun Ye Group, has been named as a recipient of the 2026 European XFEL Young Scientist Award. This prestigious honor is awarded annually to an early-career scientist who has made exceptional contributions through experiments conducted at the European X-ray Free-Electron Laser (XFEL), one of the world’s most advanced facilities for probing matter on atomic length and time scales.
The award is particularly significant because it recognizes not only technical excellence but also creativity in exploiting the XFEL’s unique capabilities to push the boundaries of science. The European XFEL produces ultra-intense, ultrafast X-ray pulses that enable researchers to capture real-time snapshots of molecular and atomic processes with atomic-scale resolution—capabilities that are extremely challenging to achieve using conventional techniques. Reflecting on this achievement, Dr. Li remarked, “It is amazing to see that what was first calculated on paper actually works so well in experiment.” Winning this award places Dr. Li among a select group of scientists shaping the future of ultrafast X-ray science.
At JILA, Dr. Li’s research focuses on precision spectroscopy using ultra-stable and coherent extreme-ultraviolet (XUV) light to investigate the low-energy nuclear transition in thorium-229 (²²⁹Th), a leading candidate for a next-generation nuclear clock. Compared with atomic clocks, a nuclear clock is expected to be far more robust against environmental perturbations and capable of operating at much higher particle densities, potentially enabling breakthroughs in precision timekeeping and searches for new physics, including dark matter detection.
Before joining JILA, Dr. Li earned a Ph.D. in physics from the University of Chicago, where he studied X-ray stimulated Raman spectroscopy. He subsequently completed a postdoctoral appointment at Princeton University, investigating ultrafast energy transfer in strongly coupled light–matter (polaritonic) systems. During this work, he recognized the critical role of high-precision measurement techniques, motivating him to join JILA to develop these capabilities further and apply them to advance XFEL-based science.
As part of the award, Dr. Li will receive a €2,000 prize and deliver a plenary lecture at the European XFEL Users’ Meeting in Hamburg, where leading researchers gather to share breakthroughs in free-electron laser science.