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Squeezing the noise out of light.

Squeezing the noise out of light

Quantum theory puts a fundamental limit on the precision with which a laser can generate light. This intrinsic randomness in the production of photons limits how much the noise, or fluctuations, in any signal can be lowered. Nevertheless, researchers have developed techniques for "squeezing" light, allowing them to reduce the uncertainty in one particular characteristic of a light wave at the expense of another, which becomes more random. By using the more predictable, or less noisy, component, they can improve the precision of a variety of optical measurements.

At this weekhs International Quantum Electronics Conference in Anaheim, Calif., several groups reported significant advances in squeezing light. In a particular, Prem Kumar and his colleagues at Northwestern University in Evanston, Ill., have reduced the amount of noise caused by the random emission of photons by a record 75 percent. "To our knowledge, this is the highest quantum noise reduction ever observed in any experiment to date," the researchers say. Their method involves splitting pulsed laser light into twin beams and measuring the number of location of photons in one beam, thereby gaining information about the photons in the unaffected twin (SN: 3/10/90, p.151).
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Title Annotation:quantum theory
Publication:Science News
Date:May 26, 1990
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