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    Liquid Crystals Slowed Down the Speed of Light a Billionfold

    Written by

    Jason Koebler

    Staff Writer

    This liquid crystal display can be used in a device to measure items traveling one trillionth of a meter per second. Photo: Dong Wei.

    Even in Elon Musk's Hyperloop, you'd only be going a fraction of the speed of light. But if we played with physics a bit, as researchers at China's Xiamen University and France's Universite de Nice-Sophia Antipolis have done, essentially any movement could be faster than the speed of light. Using a new technique, they've managed to slow the speed of light to less than one billionth of its speed in a vacuum.

    Slowing the speed of light, of course, is not going to get us to other galaxies any faster. It's not going to help with space travel at all. But slowing the speed of light does have some practical applications here on Earth. "Slow light" can be used in fiber optics to help manage bandwidth issues, and IBM's prototype microchip that can slow down light may be the first step towards commercial quantum computing.

    The idea of "slow light" is not a new one: Researchers at Harvard slowed light to a speed of about 17 meters per second in 1999. Those researchers were later able to stop light completely. In order to do that, the Harvard researchers pushed light through sodium atoms that were cooled to essentially absolute zero. Others who have achieved slow light have used lots of electricity to reach the effect.

    The Chinese and French researchers, who published their research yesterday in the journal Optics Express, conducted their experiments at room temperature and without using much power. Umberto Bortolozzo, one of the researchers who worked on the project, said his method is a more practical way to slow light than the others, and could lead to real-world applications sooner.

    Bortolozzo's method uses a liquid crystal helix—kind of a modified version of the LCD that's in your TV. When a pulse of light enters the liquid crystal helix, its waves are forced to separate as they travel through the helix. A series of dyes and the helix's shape slows down the waves, forcing the particle to wait for each individual wave before it can reconstitute itself.

    Unfortunately, instead of getting quantum computers out of this approach, its main application will be measuring speeds—very slow ones. According to Bortolozzo, the method can be used to create an instrument that can measure speeds as slow as one trillionth of a meter per second.

    The measurement will be instantaneous, which means we might be able to measure things such as ice sheet movements with it. It can also be used to create the most sensitive motion detector ever, which would be nice if you'd like to detect even the slightest shift of anything out in your yard.