Chinese Scientists Set Record by Cooling Atoms to 9.7 Picokelvin on Tiangong Space Station

Chinese scientists have cooled a cloud of rubidium atoms aboard the Tiangong space station to an equivalent temperature of 9.7 picokelvin, setting a new record for the lowest temperature achieved in an artificial material and opening new possibilities for quantum physics and precision measurement research.

The result was achieved using an ultracold atom physics facility installed in the Mengtian laboratory module of China's space station. The research involved scientists from Peking University, the Shanghai Institute of Optics and Fine Mechanics, and the Technology and Engineering Center for Space Utilization of the Chinese Academy of Sciences.

The findings were published online in the journal Science on Nov. 6, according to the Chinese Academy of Sciences.

A picokelvin is one trillionth of a kelvin. At 9.7 picokelvin, the measured temperature is extremely close to absolute zero, the theoretical lower limit of temperature at minus 273.15 degrees Celsius. The result is substantially lower than the previous reported record of approximately 38 picokelvin achieved by an international research team.

The figure describes the equivalent temperature of the atoms based on their extremely slow expansion. It does not mean that the laboratory equipment, the space station or its surrounding environment reached the same temperature, the Chinese Academy of Sciences clarified.

The experiment also enabled researchers to observe the expansion of the atomic cloud for seven seconds after it was released from confinement. That observation period is important because longer measurement times can help scientists identify weaker physical effects and investigate quantum behavior with greater precision.

The research took advantage of the microgravity environment aboard Tiangong. On Earth, gravity pulls an ultracold atomic cloud downward, limiting how long researchers can observe it after releasing it from a trap. In orbit, the atoms can remain suspended for longer periods, allowing scientists to study their behavior under weaker confinement.

The research team used an all-optical trapping method, employing laser light to hold and manipulate the atoms. It combined evaporative cooling, which removes more energetic atoms from a cloud, with a further cooling stage based on non-adiabatic expansion. The scientists also introduced an additional magnetic gradient to improve cooling efficiency in the microgravity environment.

At sufficiently low temperatures and high densities, atoms can form a Bose-Einstein condensate, a state of matter in which particles behave collectively according to quantum mechanics. Such systems allow scientists to explore fundamental physical phenomena that are difficult to observe under ordinary conditions.

The potential applications extend beyond the temperature record itself. Ultracold atoms can be used to develop highly sensitive instruments, including atom interferometers that measure acceleration, rotation and gravitational effects. Such technologies could eventually support more precise navigation systems, geophysical measurements and tests of fundamental physics.

Science News reported that the new experiment produced a Bose-Einstein condensate at around 10 trillionths of a kelvin, colder than previous records achieved in ground-based facilities and on the International Space Station.

The facility has a long development history. The project began its initial assessment in 2011 and was launched with the Mengtian laboratory module in 2022. Engineers had to adapt a large ground-based experimental system into a compact instrument capable of operating reliably in orbit, with strict limitations on power, size, weight and maintenance.

The achievement also demonstrates the growing scientific role of China's space station, which is being used for research that benefits from a microgravity environment. The station's laboratory facilities allow experiments that would be difficult or impossible to conduct in the same way on Earth.

The result does not immediately translate into a commercial technology, and further research will be needed to establish how the experimental platform can be used for practical instruments. Nevertheless, the longer observation window and record-low equivalent temperature provide scientists with a new environment for studying quantum gases and precision measurement.

For China, the breakthrough represents a notable contribution to fundamental physics and the development of space-based scientific infrastructure.