Researchers managed to cool atoms to a temperature equivalent to just 9.7 trillionths of a Kelvin (corresponding to -273.15 °C), approaching the limit known as absolute zero. This breakthrough was achieved aboard China's Tiangong space station and opens new prospects for experiments in quantum physics and the creation of high-precision sensors.
According to the study published in the scientific journal Science this Friday (the 6th), approximately 20 thousand rubidium atoms participated in the experiment. Scientists succeeded in reducing the movement of these particles to a temperature equivalent to 9.7 picokelvins (pK), which is about four times lower than the previous record of 38 picokelvins.
The resulting result also surpasses the previously established mark of 52 picokelvins, which was recorded in experiments conducted at NASA's Cold Atom Laboratory located on the International Space Station (ISS).
The team was able to track the expansion of the cloud of atoms for seven seconds after its release. This time interval is a significant step forward compared to the two seconds achieved in a previous free-fall tower experiment and approximately one second registered on the ISS.
As a result, a Bose-Einstein condensate was formed—a state of matter where a group of atoms begins to exhibit collective quantum behavior, acting as a single entity.
The experimental setup responsible for this success is located in the Mentian module of the Tiangong station. The equipment was designed to operate in orbit and includes laser systems, optical components, and control instruments in a compact design.
Absolute zero equals -273.15 °C or zero Kelvin and represents the theoretical lower limit of temperature. In this state, the thermal energy of the system reaches its minimum possible value. A picokelvin is an extremely small unit, equal to one trillionth of a Kelvin; thus, the recorded 9.7 picokelvins represent a temperature extremely close to this limit.
It is important to note that the scientists did not cool the entire space station or equipment to this state. This figure refers to the expansion energy of the atomic cloud, calculated based on the particle scattering speed after their release. This measure allows for the estimation of the aggregate equivalent temperature, as traditional thermodynamic temperature is not directly applicable to this type of experiment.
The smaller the expansion speed of the atoms, the less kinetic energy associated with the system. In addition to setting a new record, the study opens up possibilities for studying still poorly understood quantum phenomena. Future applications include experiments with exotic states of matter, quantum modeling, and the development of space atomic interferometers. These devices use the wave properties of atoms to conduct extremely precise measurements.
One potential direction is the use of these tools to study the Earth's gravitational field and test fundamental principles of physics, including the equivalence principle related to how different bodies react to gravity. Researchers also note that such low temperatures combined with long observation periods can help study quantum phenomena that are difficult to detect under normal conditions. Despite the prospects, these applications still depend on new experiments and the development of specialized instruments. The current result marks an important step in expanding the capabilities of quantum research in the space environment.
