Light Brought to a Complete Stop for One Minute
Sixty seconds may not seem like much -- it's hardly enough time to pop a bag of popcorn or make a cup of tea -- but in just one minute light can span an incredible distance, some 18 billion meters -- enough time, for example, to orbit the Moon about 20 times.
And for the first time ever, scientists stopped light dead in its tracks for one full minute -- longer than ever before.
By stopping light and capturing it within a crystal, scientists at the University of Darmstadt in Germany, effectively generated "light memory," which may one day be used to create long-range quantum networks or perhaps even unlock some clues to reaching speeds faster than the speed of light itself, according to the website Extreme Tech.
Using a technique called electromagnetically induced transparency (EIT), the research team stopped the light by capturing it in a "cryogenically cooled opaque crystal of yttrium silicate doped with praseodymium."
A simplified explanation of the rather complex experiment is as follows: When a control laser is fired at the crystal, a complex quantum-level reaction turns it the opaque crystal transparent. A second light source is beamed into the crystal before the control laser is shut off, returning the crystal to its opaque state. This leaves the light trapped inside the crystal, and the opacity of the crystal keeps the light trapped inside from bouncing around, effectively bringing light to a full stop.
This is not the first time researchers have successfully stopped light -- it was kept still for 16 seconds earlier this year, and to a brief stop in 2001 -- but it's certainly the longest.
"One minute is extremely, extremely long," said Thomas Krauss, a professor of optoelectronics at the University of St Andrews, UK, according to the New Scientist. "This is indeed a major milestone."
On top of bringing light to a full stop, the researchers learned they can successfully store and retrieve a simple image from the light.
"We showed you can imprint complex information on your light beam," said George Heinze, one of the research team members.
Heinze said it should be possible to stop light for longer periods of time if a different crystal was used, but noted that their current crystal has essentially reached its limit.
Heinze and his colleagues' research is published in the journal Physical Review Letters.