ANU physicists create the coldest cloud in the Universe

Scientists at The Australian National University have produced the coldest substance known, cooling a group of atoms to almost absolute zero (-273 degrees Celsius).

The super-cold cloud has only been replicated by a handful of international scientists. Researchers from the ANU's Department of Physics are the first in Australia to successfully reach such low temperatures. "It was a tremendously difficult and complicated experiment," Dr John Close said. "It took us three years to succeed in refining and replicating the technique pioneered in the US."

During the intricate experiment the temperature of 1 million rubidium atoms was first lowered with laser beams. Then using evaporative cooling ANU scientists produced the lowest temperature ever reached, 100 billionths of a degree above absolute zero (-273 degrees Celsius).

"The atoms with the most energy evaporate from the trapped cloud leaving the colder, less energetic atoms behind," Dr Close said.

The super-cold clouds produced at the ANU have unusual properties because they straddle the boundary between everyday and quantum physics.

"It has long been a quest in physics to find and explore this boundary and now we are one of the few in the world able to do so," Dr Close said.

Scientists will use the cold clouds to develop new technologies and investigate fundamental questions in physics. The research also paves the way for the development of atom lasers and atom interferometers that could be used in the mining industry to detect mineral and oil deposits.