Dr Jan-Theodoor (JT) Janssen was born in the Netherlands, where he studied at the Catholic University of Nijmegen (now called Radboud University). He specialised in experimental solid-state physics and received his Master's degree in 1989. He then started his PhD at the High Field Magnetic Laboratory, also at the University in Nijmegen, studying electronic nanostructures. His doctoral thesis was on the far-infrared magneto-optical properties of low dimensional semiconductor structures and organic conductors.
In 1994, JT moved to the UK under a Human Capital Mobility Fellowship of the EU. He worked as a Research Fellow at the University of Bristol, investigating the Fermi surface properties of heavy Fermion metals and superconductors using the de Haas-van Alphen effect. He won a Leverhulme Fellowship to continue this work for another two years.
JT joined NPL in 1998, where he is responsible for the research on quantum electrical standards. In 2006, he was promoted to NPL Fellow.
At NPL, his research involves a wide range of topics in solid-state physics applied to electrical metrology. Key topics are: the behaviour and transport of electrons in nanostructured devices with the aim of developing a quantum standard for electrical current; the quantum Hall effect in both traditional semiconductor systems, as well as graphene, as a primary standard for resistance; and the Josephson effect for a quantum voltage standard. He has co-authored more 100 scientific publications on these topics.
In 2015, JT launched and now heads the National Graphene Metrology Centre (NGMC), whose role it is to develop metrology and standardisation for the nascent graphene industry. JT is also a Scientific Co-Director of the Quantum Metrology Institute (QMI), which covers all of NPL's leading-edge quantum science and metrology research and provides the expertise and facilities needed for academia and industry to test, validate and ultimately commercialise new quantum research and technologies. In December 2015, JT was appointed Head of Science at NPL for SI Metrology. In this role he was leading in the strategic rebalancing of the NPL science portfolio.
From 2008 to 2016, JT was the contact person for NPL on the Technical Committee for Electricity and Magnetism (TC-EM) of the European Association of National Metrology Institutes (EURAMET), and convenor of the EURAMET DC quantum metrology experts group from 2010–2016, and a member of several international working groups.
In 2017, JT was appointed as NPL's Research Director.
JT's research interest is focused around low temperature solid-state physics and, in particular, quantum electrical effects with application in metrology. In this respect, JT has studied single electron transport in nanoscale semiconductor devices, the quantum Hall effect and the Josephson effect. JT has also done extensive research in the properties of low-dimensional systems such as graphene and other 2D materials.
JT is a Chartered Physicist and a Fellow of the National Physical Laboratory (NPL), the Institute of Physics (UK) and the Institute of Engineering and Technology. He is also the NPL Head of Science and Engineering Profession for the Government Science and Engineering Profession (GSE).