University of Sussex Media Release.
. Cool Britannia

7 October 1998
For immediate release

On September 22nd a physics laboratory at Sussex University became the coldest place in the entire universe. Researchers at Sussex succeeded in cooling 100,000 atoms to just a few hundred billionths of a degree above the coldest temperature it is possible to reach: absolute zero, or -273 degrees centigrade. Even the coldest parts of space are millions of times warmer than the temperatures reached in the Sussex lab. The researchers involved (Malcolm Boshier, Aidan Arnold and Calum McCormick) reached these temperatures in order to make what is known as Bose-Einstein Condensate; it is the first time this has been achieved in Britain.

A Bose-Einstein Condensate (BEC) occurs when atoms lose almost all their energy. An atom's behaviour and characteristics are described by its quantum state, and when a group of atoms are cooled into the lowest possible state each atom loses its individuality and becomes indistinguishable from the others. The effect is analogous to the 'locking together' of photons in a laser beam; as well as its importance for researching quantum physics, researchers hope that the BEC could be used in producing a new generation of measuring tools that will improve upon current laser technology.

The Sussex Centre for Optical and Atomic Physics, led by Professor Edward Hinds, is the world leader in magnetic mirror technology, which allows atoms to be bounced around in the same way that normal mirrors reflect light. Using this expertise, the researchers hope to build 'atom interferometers' that will enable them to perform measurements with even greater precision than is possible with lasers. "It represents the tightest control you can have over atoms - it will do for atoms what lasers have done for light", says Boshier, the head of the research team.

The behaviour of the BEC is described by the famous 'Uncertainty Principle' which says that certain pairs of facts can't be precisely known about an object - find out more information about one attribute and you forfeit information about the other. If you have a very tight hold on the momentum of an atom, for instance, you can't know exactly where it is.

In the BEC, the atoms have almost zero momentum. Since that means their momentum is well-defined, their position becomes extremely blurred: they spread out into each other, forming a blob that behaves like one enormous 'superatom'. It's big enough to photograph, and yet it still follows the laws of quantum mechanics. Although this effect was predicted over 70 years ago, it was not until 1995 that it was first seen in an experiment. Since then only a handful of groups world-wide have been able to create a BEC.

For further information please contact Malcolm Boshier or Ed Hinds, Tel. 01273 678990, or Sally Hall, Information Office, University of Sussex, Tel. 01273 678888, Fax 01273 678335, email s.l.hall@sussex.ac.uk.

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