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Tangled up in blue
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25/06/2008
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Researchers from the National Institute of Standards and Technology (NIST) and the University of Maryland have used lasers to produce ‘quantum images’, pairs of visual patterns whose features are ‘entangled’ – linked by the laws of quantum physics.
In addition to promising better detection of faint objects and improved amplification and positioning of light beams, the researchers’ technique may be useful for storing patterns of data in quantum computers and for transmitting large amounts of highly secure encrypted information.
The researchers say even the most stable laser beam brightens and dims randomly over time because of inherent quantum level ‘uncertainties’ in its properties. Controlling these fluctuations – which represent a sort of ‘noise’ – is said improve detection of faint objects and to produce better amplified images. Whilst all the noise can’t be eliminated, it can be rearranged to improve desired features in images. Using a quantum mechanical technique called ‘squeezing’, physicists can reduce noise in one property – such as intensity – at the expense of a complementary property, such as phase.
Each image comprises up to 100 distinct regions, each with its own independent optical and noise properties. A ‘pixel’ on one image forms a partnership with a ‘pixel’ on the other image. The random and unpredictable changes over time of one image are said to be matched in the other, even if the two are far apart and unable to transmit information to one another.
The researchers say the next step is to produce quantum images with slowed down light; such slowed images could be used in information storage and processing as well as communications applications.
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Author
Graham Pitcher
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