December 17, 2019
Keio University
A research group led by Takahiko Makiuchi (then a student in the Doctoral Programs at the Graduate School of Science and Technology, Keio University; currently a Project Researcher at the ERATO Saito Spin Quantum Rectification Project, Graduate School of Engineering, The University of Tokyo), Assistant Professor Yusuke Nago, and Professor Keiya Shirahama of the Faculty of Science and Technology has discovered that a thin film of molecular hydrogen remains liquid down to cryogenic temperatures and is in a state on the verge of superfluidity.
Superfluidity, like superconductivity in metals, is a dramatic quantum phenomenon that materials exhibit at low temperatures, but it has only been observed in a very limited number of substances, such as liquid helium. Molecular hydrogen (H 2 ) has attracted attention as one of the few candidate substances that could exhibit superfluidity. In this study, through elasticity measurements of a hydrogen thin film, the research group discovered that the surface of the film behaves like a liquid down to the cryogenic temperature of 1 Kelvin (minus 272 degrees Celsius) and is in a state on the verge of superfluidity. This achievement is groundbreaking in that it is the first to quantitatively show how close hydrogen has come to superfluidity, and it opens up the possibility of realizing superfluid hydrogen through new methods such as the application of high-frequency sound waves. Hydrogen is not only important for the formation of the universe and life, but under ultra-high pressure, the emergence of superconductivity is also expected. The realization of superfluid hydrogen is expected to not only demonstrate one aspect of hydrogen's diversity but also contribute significantly to the advancement of science.
The results of this research were published in the American scientific journal "Physical Review Letters" on December 13, 2019 (local time).
For the full press release, please see below.