Record-low temperature created on China’s space station.
Researchers aboard China's Tiangong space station cooled 20,000 rubidium atoms to about 10 picokelvins, forming a Bose-Einstein condensate that is colder than any made before, according to a report in Science.
Researchers report that they cooled a cloud of atoms to about 10 picokelvins, or 10 trillionths of a kelvin, aboard China's Tiangong space station. According to the paper in Science, published November 5, the atoms formed a Bose-Einstein condensate colder than any made before. Absolute zero is −273.15° Celsius, and the result sits barely above it.
The team used laser-based traps to hold 20,000 rubidium atoms and slow their motion, which cooled them. At the atomic level, temperature is tied to motion, since atoms and molecules move more slowly when it is colder. In cold atom systems, scientists define an effective temperature based on how slowly the atoms spread apart when they are allowed to expand.
Working in orbit mattered. On Earth, gravity makes clouds of atoms sag, which reduces the effectiveness of cooling. On the space station, the atoms experienced microgravity, the apparent weightlessness of an object in free fall.
To form a Bose-Einstein condensate, researchers cool a disordered group of atoms until all of them take on the same quantum state and act as a single entity. Experiments with ultracold atoms let scientists study exotic states of matter and other puzzling physics. They can also test basic concepts such as the equivalence principle, the idea that explains why objects of different masses fall at the same rate in a vacuum.
Earlier records were higher. Condensates made on the International Space Station reached effective temperatures as low as 52 picokelvins. An experiment on Earth that dropped atoms down a tower to create weightlessness reached 38 picokelvins. Drop tower experiments are limited by how long the free fall lasts, a constraint that does not apply to experiments in Earth orbit, so cold atoms in space are drawing growing interest.
At a Glance
- The atoms were cooled to about 10 picokelvins, or 10 trillionths of a kelvin, on China's Tiangong space station.
- The experiment used 20,000 rubidium atoms held in laser-based traps.
- The results were reported in the journal Science on November 5.
- The previous space-based record on the International Space Station was 52 picokelvins; a drop tower on Earth reached 38 picokelvins.
Sources
This brief was written by Brightside Report from the reporting linked above. Spot an error? Request a correction.