Large-volume magnetic trap for studying ultracold atomic hydrogen

Exploring atomic behaviors in ultra-cold environments has long been a powerful tool for discovering new properties and probing interactions between atoms. However, it is often difficult to perform experiments at these temperatures, and the required equipment can interfere with the results.

Ahokas et al. designed a magnetic trap for atomic hydrogen that allows these atoms to be cooled to millikelvin temperatures. Their design is large enough to accommodate approximately 0.5 liters of hydrogen gas.

“In our work we trap atoms with magnetic forces out of contact with material walls and cool them down to thermal velocities below several centimeters per second, aiming to slow them nearly to rest,” said author Sergey Vasiliev.

The magnetic trap is an innovative version of an Ioffe-Pritchard trap design, which uses eight superconducting magnets to create the trap chamber. The atomic hydrogen is evaporatively cooled until it reaches millikelvin temperatures and no longer interacts with the material walls of the chamber except through quantum effects. At this point, the magnetic fields are removed, and the hydrogen is studied in an ideal environment.

The researchers are planning to use their magnetic trap in several experiments, such as probing the nature of quantum reflection and gathering more accurate information on the properties and behavior of hydrogen. In particular, the atoms from this experiment will be used in a hydrogen maser-based atomic clock. The lower thermal energies from these ultracold hydrogen atoms will dramatically improve the accuracy of the clock.

“It is expected that its stability and reproducibility may be improved by three orders of magnitude, which will have a huge impact for science and technology,” said Vasiliev.

Source: “A large octupole magnetic trap for research with atomic hydrogen,” by Janne Ahokas, Aleksei Semakin, Jarno Järvinen, Otto Hanski, Arkadiy Laptiyenko, Viacheslav Dvornichenko, Kauko Salonen, Zak Burkley, Paolo Crivelli, Artem Golovizin, Valery Nesvizhevsky, Francois Nez, Pauline Yzombard, Eberhard Widmann, and Sergey Vasiliev, Review of Scientific Instruments (2022). The article can be accessed at https://doi.org/10.1063/5.0070037 .