Atomic gas cooled to 0.00000000005 degrees Celsius above absolute zero
T. Kovachy et al/Physical Review Letters 2015
A swarm of atoms in a Stanford lab has become the coldest stuff on Earth. At about 50 trillionths of a kelvin, the atoms’ temperature was about a tenth of the previous record.
The temperature of a sample depends on how fast its constituent components move relative to each other. Quantum physicist Mark Kasevich and his team started with a cold gas made up of about 100,000 tightly packed rubidium atoms. Within a few seconds, the atoms spread apart, because some were moving faster than others. But then Kasevich’s team zapped the sample with a laser that countered the motion. The farther an atom had roamed (and thus the faster it was moving), the more of a decelerating nudge it received. All the atoms slowed to a crawl, the researchers report in the April 10 Physical Review Letters, corresponding to the new record-low temperature.