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Physicists 'freeze' light for record-breaking minute

By Kristen Butler, UPI.com   |   July 26, 2013 at 12:37 PM

Light -- the fastest thing in the universe -- is exceedingly difficult to halt, and German researchers have managed to freeze light for a record-breaking one minute.

They also successfully stored and retrieved data in the experimental beam in the form of a 100-micrometer-long picture with three horizontal stripes on it -- a crucial step for quantum information processing.

Light travels about 300 million meters per second in a vacuum, and one minute is a very long time. In the one minute the light was stopped, it could have traveled about 11 million miles -- more than 20 round trips to the moon.

In 1999 scientists slowed light to just 17 meters per second, then in 2001 halted it completely for a fraction of a second. Earlier this year, researchers held light still for 16 seconds using cold atoms.

George Heinze and colleagues at the University of Darmstadt, Germany fired a laser at an opaque crystal. This sent the crystal's atoms into a quantum superposition of two states, making it transparent to a narrow range of frequencies -- a process called electromagnetically induced transparency (EIT).

Then, researches fired a second laser into the crystal, trapping it there by switching off the first laser, ending transparency and returning the crystal to its opaque state.

A magnetic field can extend storage time, but complicates laser configuration. To break the one-minute barrier, researchers created an algorithm to find the perfect magnet and laser combination.

Researchers say that with better materials, "there is clear hope that this could be a solid-state platform able to achieve coherent light storage for tens of minutes."

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