New coldest temperature record: 38 picokelvins

The record has been broken for the coldest temperature ever achieved with the cooling of rubidium gas to 38 picokelvins (3.8 * 10-11 K) . The work could lead to new insights into quantum mechanics.

Temperature is a measure of the energy of the vibrations of atoms or molecules. The lowest temperature theoretically possible is absolute zero - 0 K or -273.15 ° C (-459.67 ° F) - which would require a complete cessation of movement. That's probably impossible in practice, but physicists have shown for decades that we can get really, really close, using lasers to dampen atomic motion.

In the journal Physical Review Letters, German scientists report that it has gotten closer to zero than ever.

Professor Ernst Rasel of Hannover Leibniz University and his co-authors placed 100,000 rubidium atoms inside a magnetic trap on top of the 110-meter-high University of Bremen drop tower. The trap forms what is called a "matter-wave lens" which, by focusing the atoms to infinity, cools them to the point of converting them into a Bose-Einstein condensate (BEC), a state of matter in which collections of atoms can display quantum behavior as if they were a single subatomic particle / wave.

By turning off the trap, the condensate expands in all directions and cools even more. The BEC was then allowed to fall freely down the length of the tower while the detectors observed its behavior.

The whole process takes just two seconds, although the models suggest 17 seconds is possible, and the authors hope to exploit this longer timeline to explore the behavior of the BEC with the vibration distortions removed.

In an accompanying opinion piece, Dr Vincenzo Tamma of the University of Portsmouth, who was not involved in the research, said the work could " test gravity at the quantum level."The interference patterns in the BEC are determined in part by gravitational effects. Since the inconsistencies between our understanding of quantum physics and general relativity's description of gravity represent perhaps the greatest puzzle in physics without Resolving, the work offers the opportunity to explore physics at its most fundamental.Tamma also sees the potential of the technique to search for certain forms of dark matter.

One hundred thousand atoms may seem like a lot, but in reality it is about 50 million times less than the head of a pin, more or less due to the variation in atomic size and the head of a pin. The coldest temperature ever reached in something that can be seen was established when a 400 kilogram (882 pound) block of copper was cooled to 0.006 K. To achieve this, the researchers needed the lead to have been mined thousands of years ago, which It allowed time for the radioactive isotopes formed by exposure to other radioactive elements in the mineral to decompose. This was achieved thanks to the fortuitous discovery (for us) of a Roman galley that sank off the coast of Sardinia with Spanish lead destined for the Roman civil wars.

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