Researchers at the University of Rochester have encoded an entire image's worth of data in a single photon, slowing down the photon for storage and retrieving the photon and the image intact. The test image consisted of a simple stencil with the letters "UR," but the researchers say a "tremendous amount of information can be stored with the new technique."
John Howell, associate professor physics and leader of the team that created the device explained, "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 6-megapixel camera." Ryan Camacho, a graduate student working with Howell added, "You can have a tremendous amount of information in a pulse of light, but normally if you try to buffer it, you can lose much of that information. We're showing it's possible to pull out an enormous amount of information with an extremely high signal-to-noise ratio even with very low light levels."
Quantum mechanics describe a photon of light as both a particle and a wave. As a wave, the photon passed through all parts of the stencil at once, carrying the "UR" image with it. The pulse of light was delayed in a four-inch cell of cesium gas heated to 100 degrees C. Many pulses can fit into the cell at the same time.
Alan Willner, professor of electrical engineering at the University of Southern California said, "The parallel amount of information John has sent all at once in an image is enormous in comparison to what anyone else has done before. To do that and be able to maintain the integrity of the signal--it's a wonderful achievement."
After completing this demonstration, Howell said, "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."
For a picture of the image and a link to a diagram of the apparatus, see Ultra-Dense Optical Storage--on One Photon.
