Congratulations to Dr. Takamasa Momose, who, alongside Susumu Kuma of the RIKEN Atomic, Molecular and Optical Physics Laboratory, Japan, has been selected by Physics World for his work with observing the superfluid phase in molecular hydrogen for the first time.
Molecular hydrogen is the simplest and lightest of all molecules. Theorists predicted that it would enter a superfluid state at a temperature between 1‒2 K. But this is well below the molecule’s freezing point of 13.8 K, so Momose, Kuma and colleagues first had to develop a way to keep the hydrogen in a liquid state. Once they did that, they then had to work out how to detect the onset of superfluidity. It took them nearly 20 years, but by confining clusters of hydrogen molecules inside helium nanodroplets, embedding a methane molecule within the clusters, and monitoring the methane’s rotation, they were finally able to do it. They now plan to study larger clusters of hydrogen, with the aim of exploring the boundary between classical and quantum behaviour in this system.
The list was developed by the Physics World editorial team who reviewed all the scientific discoveries they have reported on since 1 January and picked 10 that they consider to be the most important. In addition to being reported in Physics World in 2025, the breakthroughs must meet the following criteria:
- Significant advance in knowledge or understanding
- Importance of work for scientific progress and/or development of real-world applications
- Of general interest to Physics World readers
See the full list of the top 10 Breakthroughs of the Year in physics for 2025 here. Read more about Dr. Momose research here.