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Lasers Can Cool? Semiconductor Scientists At Denmark's Niels Bohr Institute Say Yes

First Posted: 01/23/2012 1:40 pm Updated: 01/23/2012 1:40 pm

Semiconductor Laser

Here's a hot tip: scientists at Denmark's Niels Bohr Institute have figured out a cool new way to lower the temperature of hot semiconductors.

In a seemingly paradoxical new study, the scientists showed that light from a laser caused the temperature of semiconductor material to drop--and not by just a few degrees. The temperature fell to -269 Celsius. That's almost as cold as matter can get!

The research is considered a breakthrough in optomechanics, the interaction between light and mechanical movement, and it may be essential for the what scientists see as a coming revolution in quantum computers.

The cooling works by what co-author Koji Usami calls a "complex and fascinating" interplay between a 160-nanometer-thick semiconductor membrane and the laser light.

Here's how it works: Laser light shone on the membrane is reflected onto a mirror at the back of the laser. This forms a feedback loop, a bit like an electric guitar squealing into its own amplifier. Meanwhile, some of the light heats the membrane, which expands. This means the distance between the membrane and the laser's mirror is constantly changing. Scientists can control the laser so that the fluctuation slows, thereby cooling the membrane.

Usami says

"This is a new optomechanical mechanism, which is central to the new discovery. The paradox is that even though the membrane as a whole is getting a little bit warmer, the membrane is cooled at a certain oscillation and the cooling can be controlled with laser light. So it is cooling by warming!"

And the discovery is as exciting as it is novel. According to co-author Eugene Polzik, "The potential of optomechanics could, for example, pave the way for cooling components in quantum computers."

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Filed by Travis Korte  |