Prof Jan-Theodoor (JT) Janssen FREng FRS is the Chief Scientist and International Director at the National Physical Laboratory and is member of the Executive team. In his role as Chief Scientist he’s providing scientific leadership across a wide range of disciplines (Physics, Engineering, Chemistry, Material Science, Mathematics) as well as others in Medical and Life Sciences areas.
JT is a physicist and his research involves a wide range of topics in solid-state physics applied to metrology applications and material characterisation. Key topics are the behaviour of electrons in nanostructured devices with the aim of developing a quantum standard for electrical current, the quantum Hall effect, and the Josephson effect.
JT is a Fellow of the Royal Academy of Engineering, the Institute of Engineering and Technology and the Institute of Physics. In 2022 JT was elected to the International Committee for Weights and Measures (CIPM) at the 26th General Conference for Weights and Measures in Versailles and appointed the President of the Consultative Committee for Ionising Radiation (CCRI). In 2023 JT was appointed on the council of the UKRI Science and Technology Facilities Council (STFC). He is a visiting professor at the University of Lancaster.
In 2023 JT received the IOP James Joule Medal for outstanding contributions to applied physics, recognising his ground-breaking work in quantum electrical metrology.
In 2026 JT was elected a Fellow of the Royal Society.