Klaas-Jan Tielrooij founded the Ultrafast Dynamics in Nanoscale Systems group at ICN2 in October 2018 as a Junior Group Leader. In 2022 he was promoted to Senior Group Leader. He also works as an Associate Professor at Eindhoven University of Technology (the Netherlands). Before joining the ICN2, he was a Research Fellow at the Institute of Photonic Sciences (ICFO). Between 2018 and 2020, he was Visiting Professor at the Graduate School of Excellence Material Science in Mainz (Germany). He obtained his Ph.D. from the University of Amsterdam (the Netherlands) in December 2010.

Klaas-Jan has received several prizes, including the Dutch National Physics Thesis Prize, and competitive personal grants including ERC Starting and Proof of Concept grants and a Spanish Ramón y Cajal grant. Prof Tielrooij has authored more than 65 peer-reviewed publications, with more than 8,500 citations, and he has given more than 50 invited talks.