Scientists use light to store information
- 25 January, 2007 08:06
Scientists claim to be able to attach an image to a photon and retrieve it later.
Scientists at America's University of Rochester used their college logo, consisting of a few hundred pixels for the experiment. The photon or pulse of light was slowed down 100 nanoseconds and compressed to one percent of its original length
Researcher John Howell, assistant professor of physics at Rochester, is now working on delaying dozens of pulses for as long as several milliseconds, and as many as 10,000 pulses for up to a nanosecond in a four-inch cell of cesium gas at a warm 100 degrees Celsius.
Previous optical buffering trials have found most information carried by the light is lost. This achievement is important because engineers are trying to speed up computer processing and network speeds using light. Their systems slow down when they have to convert light to electronic signals to store information, even for a short while.
Howell said: "It sort of sounds impossible, but instead of storing just ones and zeros, we're storing an entire image. It's analogous to the difference between snapping a picture with a single pixel and doing it with a camera -- this is like a six-megapixel camera."
"Now I want to see if we can delay something almost permanently, even at the single photon level. If we can do that, we're looking at storing incredible amounts of information in just a few photons."
Other light storage projects
Last year, NTT researchers in Japan slowed light down by having it enter a crystal with nano-scale holes inside it. IBM researchers have diverted light beams into microscopic rings to form a delay line. And a team at Harvard University has worked on slowing light down by passing it through very cold structures.
These four different research projects illustrate how important it is when building an optical computer not to have to convert from photons to electrons if data has to be stored in a buffer. The feasibility of long-term light storage, for periods longer than a few nanoseconds, has not been demonstrated at all though. These projects are to do with caching information inside an optical computer, not storing data outside it.