A team of researchers affiliated with several institutions in Germany and two in France has set a new record for the coldest temperature ever recorded in a lab setting—38 picokelvins, reports Phys.org. In their paper published in the journal Physics, the group describes their work with a time-domain matter-wave lens system. Prior research suggested that the coldest possible temperature is absolute zero—0 Kelvin. The researchers created the coldest environment ever using a quantum gas lens and the famous Bremen Drop Tower in Bremen, Germany, which has a 122-metre-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 off the trap, allowing the cloud to expand in every direction (and making it even colder) as it fell down the length of the tower. Detectors on the sides of the tower measured the kinetic energy of the atoms in the cloud as they passed by. The process lasted two seconds.
https://phys.org/news/2021-10-coldest-temperature38-picokelvins.html
