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There is almost: an atomic laser that produces a beam of matter

There is almost: an atomic laser that produces a beam of matter

An atomic laser that can continuously produce a beam of matter approaches one step. Optical lasers, which we use in printers, measuring equipment, and ophthalmology, among other things, emit a narrow beam of coherent light, which is made up of light waves that move in perfect synchrony. According to quantum mechanics, particles such as atoms can also be described as waves. This means physicists can create an atomic laser by making matter waves from atoms move synchronously, like a single large matter wave.

Atomic lasers can be used in precision sensors with applications in navigation research and physics in gravitational effects. For these applications it is necessary to maintain the waves of the material for a long time. A group of physicists from the University of Amsterdam (UvA) has developed a method for this. they consequences appeared last week in temper nature

The basis of an atomic laser consists of thousands to millions of atoms that are all in the same state at the same time, thus forming one coherent wave of matter. This is called Bose-Einstein condensation. You can compare it to a group of soldiers who make a perfect stride, making them appear as one.

absolute zero

It is not easy to get atoms to form a Bose-Einstein condensate. For this you have to cool them in a vacuum to almost absolute zero (-273 ° C), so that they do not move with difficulty. This is done by using laser light that slows down the atoms, causing them to cool. When a cloud of atoms is cool enough and compressed enough, it naturally forms a Bose-Einstein condensate.

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Bose-Einstein capacitors were first manufactured over 25 years ago. This soon produced the first atomic laser. But these can produce wave-like pulses of matter for a fraction of a second. A Bose-Einstein condensate only exists for a short time and is weak, because you lose atoms in it when it heats up or forms molecules. A little scattered laser light can destroy it. This is tricky, because laser light is necessary for cooling.

“To keep an atomic laser without a pulse, you have to constantly add ultra-cold atoms to the Bose-Einstein capacitor to make up for the atoms you’re losing,” UvA physicist Florian Shrek says over the phone. He and his colleagues developed a technique for this. “In 2012, we showed that it was possible to make a Bose-Einstein condensate surrounded by a cloud of laser-cooled atoms,” he says. In that laser-cooled cloud, atoms can collide like billiard balls. One gets all the kinetic energy so that the other is so slow that it can get into a Bose-Einstein condensate.

Cooling step by step

The latest development concerns the cooling of atoms with a laser, which is done step by step. At each step, a different laser cools the atoms further. Other experiments run these cooling steps one by one in the same space. In our setup, each step takes place elsewhere,” Schreck says. “This reduces the risk of light from one step interfering with the next.”

This results in an arrangement with a continuous flow of atoms being cooled step by step to eventually end up in the laser-cooled cloud. From there they feed a Bose-Einstein capacitor that is held for a long time at random.

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This is almost an atomic laser, but not yet. Schreck: “The next step is to add some kind of output so that we can extract a continuous atomic laser beam from the Bose-Einstein capacitor.” If the laser is successful, it is ready to use.