Scientists use lasers to cool atoms to temperatures colder than deep space, creating a single 'super-atom.'

The process of laser cooling relies on the Doppler effect to slow down atomic motion. When an atom moves toward a laser beam, it absorbs photons that push against its direction of travel, effectively acting like friction. By using six laser beams to surround the atoms, scientists create an 'optical molasses' that reduces the atoms' kinetic energy to near-zero levels.In 2021, a team at the University of Bremen in Germany achieved a record-breaking temperature of 38 picokelvins, which is 38 trillionths of a degree above absolute zero. For comparison, the average temperature of deep space is about 2.7 Kelvin. This experiment was conducted at the Bremen Drop Tower, where researchers utilized a 120-meter tall vacuum shaft to achieve weightlessness for several seconds.At these extreme temperatures, matter enters a fifth state known as a Bose-Einstein Condensate (BEC). First predicted by Albert Einstein and Satyendra Nath Bose in the 1920s, this state was not physically realized until 1995 by Eric Cornell and Carl Wieman. In a BEC, the individual identities of atoms disappear as their wave functions overlap, causing them to behave as a single macroscopic quantum wave.This research is vital for developing ultra-precise sensors and quantum computers. By studying atoms in this state, scientists can observe quantum mechanical properties that are usually hidden by thermal noise. These 'super-atoms' allow for the measurement of gravity and time with unprecedented accuracy, potentially leading to new discoveries in dark matter and fundamental physics.