A new way of controlling the expansion of matter in a freely-falling Bose-Einstein condensate (BEC) has produced the coldest effective temperature ever measured: 38 pK (10-12 K) above absolute zero. The method, which allowed researchers in Germany and France to image the condensate’s evolution for more than two seconds, opens the door to enhanced measurements of the gravitational constant g and photon recoil, and could even offer an alternative means of detecting gravitational waves. Image credit - Pixabay At two billionths of a degree above absolute zero, however, this wasn’t quite cold enough. So the team ran an experiment at the Bremen Drop Tower research facility, dropping the BEC trap 120 m (393.7 ft). During the free fall, the team switched the magnetic field containing the gas off and on repeatedly. To do so, the researchers started with a cloud of 100,000 rubidium atoms trapped in a magnetic field in a vacuum chamber. They then cooled this down to form a quantum gas called a Bo...
“Everything is theoretically impossible, until it is done.”