Distorted particles of light, which have been jammed using quantum mechanics, offer a new approach to dense and secure data.
Holograms that create 3-D images and are used as security features on credit cards are usually made with patterns placed with laser light beams. Recently, physicists have found ways to create holograms with entangled photons instead. Now it is, literally, a twist to a wind.
Entangled photons that travel along corkscrew paths result in holograms that offer the possibility of dense and ultrasecure data encryption, researchers report in an upcoming study. Physical Review Letters.
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Light can move in different ways, including up and down and sideways to polarized light patterns. But since it carries a type of spin known as orbital angular momentum, it can also propagate into spirals that resemble twisted pasta.
Like any other photon, distorted versions can be entangled to act as essentially a single entity. Something that affects one pair of entangled photons immediately affects the other, even if they are far apart.
In previous experiments, researchers sent data over the air in twisted pairs of photons (SN: 8/5/15). The approach must allow high-speed data transmission, because light can come with different weights of twists, with each twist serving as a different communication channel.
The same approach was used to mark the marks in the hograms. Instead of transmitting information in multiple channels, twisted light channels twist photon pairs with different amounts of information into a single hologram. The more important the orbital angular state is involved, the more information researchers can pack into a hologram.
In addition to cramming more data into logs, the increasing variety of encryption used to boost data security features. Anyone who wants to read the information must know, or guess, how it was brought to light.
To twist a hologram based on two types, says scientist Xiangdong Zhang of the Beijing Institute of Technology, you need to twist the right combination of 80 possibilities to decode the data. Bumping that up to combinations of seven dis- plications leads to millions of possibilities. That, Zhang says, “should be enough for our encryption to have enough holographic system security levels.”
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The researchers demonstrated their skill by writing words and letters on holograms and reading their data again in distorted light. Although researchers have produced images from holographic data, says scientist Hugo Defienne of the Paris Institute of Nanoscience, the actual storage should not be confused with holographic images.
Defienne, who was not involved with the new research, says other quantum holography devices, such as his efforts with polarized photons, can produce direct images of objects including microscopic structures.
“[Their] it is a very different idea. . . from our approach in this sense, Defrienne says. They “store holography for information” rather than creating the typical 3-D images that most people associate with holograms.
The perverse light data store that Zhang and his colleagues show is slow, requiring about 20 minutes to decode the image of the acronym “bit” for the Beijing Institute of Technology where the experiments were conducted. And the safety, which the researchers have shown to be still relatively low, included only up to six different forms of light in their experiments.
Zhang is confident that both limitations can be overcome with technological advances. “We think our technology has potential application in quantum information encryption,” especially quantum image encryption.
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