New record set for coldest temperature

The coldest possible temperature that can exist is absolute zero Kelvin. Research has also shown that as substances grow colder, some begin to change their properties. Liquid Helium, for example, becomes a superfluid at very low temperatures.

In this new effort, the researchers have created the coldest environment ever by using a lens made out of a quantum gas and Bremen Drop Tower, which has a 122-meter-high drop tube.

They started by creating a gas cloud at the top of the tower made of Rubidium atoms. The cloud was held in place by a magnetic trap that also served as a matter-wave lens that focused the atoms in the cloud into a Bose-Einstein condensate, making the cloud grow cold.

The researchers then turned the trap off, allowing the cloud to expand in every direction (and making it even colder) as it fell down the length of the tower. Detectors measured the kinetic energy of the atoms in the cloud as they passed by. The process lasted only two seconds, but that was enough to show it produced a record for the coldest temperature ever recorded in a lab setting—38 picokelvins (-273.15º C(.

The researchers note that small changes in the setup, such as reducing the number of atoms in the cloud, could possibly lead to even colder temperatures.