Scientists cool atoms to record low of 10 picokelvins in space

Scientists have cooled a collection of atoms to about 10 picokelvins, or 10 trillionths of a kelvin, marking a new record low temperature. This achievement was reported on November 5 in Science. The atoms formed a Bose-Einstein condensate, a quantum state of matter that is colder than any previously recorded.

To reach this unprecedented chill, researchers conducted their experiment in space. The atoms orbited Earth aboard China’s Tiangong space station, where laser-based traps were used to contain 20,000 rubidium atoms and reduce their motion, effectively cooling them. At an atomic level, temperature correlates with motion; as the temperature decreases, the atoms and molecules around us move more slowly.

On Earth, gravitational forces can cause clouds of atoms to sag, which diminishes the effectiveness of cooling. However, in the microgravity environment of the space station, the atoms experienced apparent weightlessness, allowing for more effective cooling.

Creating a Bose-Einstein condensate involves cooling a disordered group of atoms until they all occupy the same quantum state, behaving as a single entity. By experimenting with ultracold atoms, researchers can explore exotic states of matter and investigate fundamental physics concepts, such as the equivalence principle, which explains why objects of different masses fall at the same rate in a vacuum.

Previously, Bose-Einstein condensates were created on the International Space Station at effective temperatures as low as 52 picokelvins. An Earth-based experiment, where atoms were dropped down a tower to induce weightlessness, achieved 38 picokelvins. However, drop tower experiments are limited by the duration of free fall, a constraint that does not apply to experiments conducted in orbit. Thus, the potential for studying cold atoms in space is significantly enhanced.