Professor James Millen is a Professor of Physics, an experimental quantum scientist, and Director of King's Quantum (a multidisciplinary research initiative) in the Department of Physics at King's College London.

He studies novel quantum technologies and fundamental physics at the nanoscale. He is proud to support his research community, and from 2022-2025 founded and led LeviNet, an international research network of over 70 institutions. His research has been supported by UKRI, the ERC, the Leverhulme Trust and through direct industrial investment.

He completed his MSc in Physics at Imperial College London, and his PhD in experimental atomic physics at Durham University, under the supervision of Dr. M. P. A. Jones. During this work he created the world’s first gas of ultra-cold strontium Rydberg atoms.

James worked with Professor Peter Barker at University College London in the new field of levitated optomechanics. In pioneering work, they used focused laser beams and optical cavities to cool and control the motion of charged silica nanoparticles. Together with Prof. Janet Anders they undertook a paradigmatic study into microscale non-equilibrium thermodynamics.

James was awarded a Marie Skłodowska-Curie Research Fellowship to work in the Quantum Nanophysics group of Prof. Markus Arndt at the University of Vienna. The group developed techniques which will enable the exploration of the mass limit of quantum physics in uncharted regimes. While in Vienna, James pioneered the study of rotational optomechanics, developing the most frequency stable mechanical object ever created.

Public Engagement

To complement his research, James has fostered a keen interest in Outreach, Public Engagement, and Science Communication, and is currently Lecturer in Quantum Theory to the Public at the Royal Institution. He runs The Quantum Workshop and Seeing the Unthinkable mobile experiments, has written for the Guardian and Physics World, and has acted as scientific advisor for two BBC documentaries. More details can be found on his personal websites:

Research: www.levi-nano.com
Outreach: www.thequantumworkshop.com

Research interests

• Opto- and electro-mechanics
• Nano-thermodynamics & non-equilibrium physics
• Macroscopic quantum physics
• Analogue simulation
• Device development

How does physics change at the microscale? James’ research team explores this broad question in the lab, shedding light on quantum mechanics and its limits, and the role of stochastic thermodynamics in nature. To do this, they engineer the environment of nanoscale objects levitated in vacuum using light and electrical fields. The advances in nanofabrication, imaging and control technologies realised by the group are then exploited for the development of real-world sensing applications.