Chinese scientists cool rubidium atoms to 9.7 picokelvin on Tiangong space station

Chinese scientists have cooled a cloud of rubidium atoms to 9.7 picokelvin aboard the Tiangong space station, keeping it stable for observation for seven seconds, according to results published in the journal Science.

The experiment was carried out in the ultra-cold atom physics rack aboard China's space station. The project began feasibility studies in 2011, and its experiment system was launched with the Mengtian module in 2022. It was organized by the Technology and Engineering Center for Space Utilization under the Chinese Academy of Sciences (CAS), while completed by Peking University and the Shanghai Institute of Optics and Fine Mechanics (SIOM) of the CAS.

The experiment

The previous record was 38 picokelvin, set by a German team in 2021. The Chinese team used an all-optical trap to hold the atom cloud, then lowered the laser intensity to cool it further through evaporation, and finally applied a deep-cooling step called non-adiabatic diffusion.

Compared with the magnetic-trap approach used internationally, the Chinese method is less sensitive to magnetic interference, easier to control precisely in space, and has more available optical accesses. Consequently, it is compatible with a wider range of quantum simulation experiments.

To achieve such a target, the team integrated a ground-based experimental system of around 20 cubic meters and 10 tonnes into a rack of just 0.7 cubic meters and 0.5 tonnes, overcoming key challenges in ultra-high vacuum systems, high-power fiber lasers, long-term laser frequency stabilization and high-precision optical integration.

Observation time and applications

Ground experiments can watch atoms for only about 0.05 seconds, the International Space Station for roughly 1 second, and China's space station now for 7 seconds.

"The longer we can observe, the more likely we are to find new and fainter physical phenomena," said Xiong Wei, a co-first author of the paper.

This achievement could help scientists study phase transitions, non-equilibrium dynamics and quantum many-body correlations at extremely low temperatures, and support research into early-universe simulation and ultralight dark matter detection, said Chen Weibiao, a researcher at SIOM.

Lyu Congmin, chief designer of the space application system of China's manned space program, said: "We welcome scientists from all over the world to conduct experimental research with the ultra-cold atom physics rack on the Chinese space station to make new contributions to the scientific community."

Why it matters

• The result was published in the journal Science.
• The previous record was 38 picokelvin, set by a German team in 2021.
• The atom cloud was kept stable for seven seconds aboard the Tiangong space station.
• The technology could support high-precision atomic clocks, atom-interferometry inertial measurement and quantum computing.

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Sources

• scmp.com: Chinese scientists chill atoms to record low on Tiangong space station | South China Morning Post
• bignewsnetwork.com: China sets world record for coldest temperature aboard space station

This article was drafted with AI assistance and checked against the sources above. Company claims are reported as claims. Cover image is AI-generated.