The first image encoded, stored, and retrieved from a single photon: the right panel is the original image, and the left panel shows the image after it was stored in heated cesium gas and then retrieved.
Credit: University of Rochester
SYDNEY: A single photon has been used to create and store a nearly perfect copy of an entire image at a U.S. laboratory, in an important step toward light-based data storage.
The achievement may open the door to 'light computers' that process and store information using simple beams of light instead of the electrical signals currently used in computers.
The image - 'UR' for the University of Rochester in New York, where the research took place - was made by shining a single photon of light through a tiny stencil of the letters.
By using a single photon, the team played on a strange property of light: quantum mechanical theory holds that while light is emitted as discrete particles called photons, it can also be thought of as a wave.
As a wave, the light passed through all parts of the stencil at once, carrying the 'shadow' of the UR with it. The photon then entered a 10 cm long tube filled with cesium gas heated to 100° Celsius, where it was slowed and compressed.
Slowing and shrinking the image-carrying photon allowed the team to fit many pulses - up to one hundred - in the cell at once. Additionally, while the initial test image consisted of only a few hundred pixels, the technique can be used to store much more information, according to the researchers.
Squeezing so much information into so small a space and retrieving it intact, they said, opens the door to optical buffering - storing information as light.
"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," said Ryan Camacho, a member of the research team. "We're showing it's possible to pull out an enormous amount of information with an extremely high [quality] even with very low light levels."
"It sort of sounds impossible, but instead of storing just ones and zeros, we're storing an entire image," said team leader John Howell.
Optical buffering is an area of increasing interest, as engineers work to speed up computer processing and network speeds using light instead of electrons as a data-carrying medium. In the past, their efforts to create a light computer have been delayed by an inability to efficiently convert light to electronic signals to store information. This new technique could provide a way round this problem.
The buffered pulse created by the team is essentially a perfect original; there is almost no distortion, no additional diffraction, and the characteristics of the original light wave are all preserved.
"The ... amount of information [the team] has sent all at once in an image is enormous in comparison to what anyone else has done before," said Alan Willner, a professor of electrical engineering at the University of Southern California in Los Angeles. "To do that and be able to maintain the integrity of the signal - it's a wonderful achievement."
Howell and his team have so far been able to delay light pulses by 100 nanoseconds (100 billionths of a second). They're currently working towards delaying dozens of pulses for as long as several milliseconds, and as many as 10,000 pulses for up to a nanosecond.
"Now I want to see if we can delay something almost permanently, even at the single photon level," said Howell. "If we can do that, we're looking at storing incredible amounts of information in just a few photons."
A single photon
wow this blows my mind, but i have no understanding of how this works with my limited physics knowledge, is a light wave, therefore a photon, infinitely divisible? plus how much area does it fill at once? ie. effectively how wide is it?
Photons are fundamental,
Photons are fundamental, they're not divisible at all. We can't really talk of an effective area or width but the photon could be anywhere where it's wavefunction will allow.
As above so below
So what does this quality of a single photon tell us about the fundamental intelligence of Nature at such a basic level ?
photon information storing
with this kind of technology one could not only store, but beam information at the speed of light... this could unlock things like teleportation! (in particles first)