Bose-Einstein Condensation & the Atom-Laser

Nearly forty years ago the first laser was demonstrated. It was a remarkable scientific breakthrough and provided us with a very special form of light. The laser gives us the best control over light that nature allows. For example light from a laser travels in one direction whereas light from a bulb goes in all directions. Light from a laser is one colour whereas light from a bulb is a mixture of many colours.
 

Instead of the randomness we get from a light bulb, a laser provides "order" so we call this "coherent" light. Although there was some uncertainty about how useful the laser might be when it was first demonstrated, but these days lasers have found innumerable innovative applications. We use them for high speed communications via optical fiber, we use them in medicine for correcting vision problems, we use them for monitoring pollution levels in the atmosphere above cities, and we use them at home to listen to a CD. Lasers are also an important research tool at Otago.
 

Our research is not actually about lasers, but aims to control atoms in a similar way that lasers control light. That is, we want to develop a device which produces a coherent beam of atoms, rather than a coherent beam of light. This device is called an atom-laser and it provides the best control over the motion and position of atoms that nature allows. We can make an atom-laser using an exotic new state of matter called a Bose-Einstein condensate. Our everyday encounters with atoms involve solids, liquids, and gases - we call these the three states of matter - but a Bose condensate is different from these, it's totally new! It was only discovered recently because it forms under astronomically cold temperatures. Just to give you an idea about how cold, the surface of the sun is 6000K and ice forms at 273K (temperatures I consider to be quite similar), whereas a Bose condensate forms at one billionth of a degree about absolute zero (much colder)!
 

In a normal gas we can think of atoms like ping-pong balls all moving about in random directions, but in a Bose condensate all the atoms lose their individual identities and form "coherent matter". An analogy to this is to think about the atoms as being like soldiers on parade - they'e all dressed the same and they move in perfect order.

Now that we have coherent matter, to make an atom-laser all we have to do is extract atoms from the Bose condensate in the form of a coherent atomic beam. Well, actually a number of research groups (including ours) have already done this.  We did this in a very crude way - think of the Bose condensate as being held in a container much like water in a bowl: to get a beam of coherent matter we just puncture the container and Bose condensate leaks out.
 

The atom-laser could well be the most profound technological development from Bose-Einstein condensation. Although rudimentary demonstrations of atom-lasers (such as ours) have been reported, when fully developed, atom-lasers will provide researchers with atom sources as different as lasers are from candlelight.
 

It is impossible to predict exactly what applications this technology could lead to, but the similarities to the laser have created considerable excitement and optimism. At a guess, we expect that atom-lasers will be used to make tiny (or nano) structures for (say) a new generation of quantum computers currently being conceived in various Physics labs around the world. At present, atom-laser experiments are complicated, but in our future work we will be investigating key features of atom-laser innovation in the hope of making progress towards a practical device.
 

For more introductory level information on Bose-Einstein condensation, please visit the following websites: