The novel technique behind such advances is based on a bizarre trick of nature that occurs within the murky realm of quantum physics.

In the quantum world, objects too small to be seen easily, such as electrons, can behave in ways that violate common sense. For example, a phenomenon known as entanglement allows two or more objects to become linked in such a way that, no matter what distance separates them -- even the entire universe -- watching one instantly communicates what the other is doing.

Morgan Mitchell, a quantum optics researcher at the University of Toronto, and colleagues have been working on performing just such entanglements with photons, the packets of energy that compose light. In addition to its two-places-at-once ability, entanglement also causes multiple photons to behave as if they were one. For example, entangling three photons means they behave as a single photon, but with three times its normal energy.

"It looks like a super-photon," Mitchell told United Press International. "For this experiment, the hardest part was making them indistinguishable, which means not just putting them in the same location, but making sure they're there at the same time, that they are the same color, and going in the same direction. You have to guarantee all of these (aspects) at once."

Despite the esoteric-sounding terms, entangling photons can produce some highly practical and valuable results. For example, it could help pack data more tightly onto compact disks. The data are stored on the disks' aluminum-coated reflective layer. That layer encodes data in thousands of microscopic pits, each about a half-micron wide, or 20 times narrower than a single blood cell.

The pits on a disk reflect light differently than "lands" -- the smooth parts of its surface. Each pit or land represents a bit of information. CD players read data from the disks by running over them like phonograph needles did over vinyl records, but without physical contact.

Normally, the size of the tiniest feature that can be seen is no better than the wavelength used to see it. This physical barrier is called the "diffraction limit," Mitchell explained.

The wavelength of light typically used in CD players is about 780 nanometers, or 780 billionths of a meter. This is very small -- less than one-hundredth the diameter of the average human hair. Currently, a compact disk can harbor enough pits to encode up to roughly 783 million bytes of data, or about 74 minutes of music.

By entangling photons, however, Mitchell and colleagues said they can beat the diffraction limit.

"Because the three photons behave like one super-photon," he explained, "the super-photon gives us a resolution that is three times better than an individual photon would."

Although the researchers used 810 nanometer wavelength photons, which function as infrared light -- outside the visible range -- the super-photons allowed them to resolve details on the scale of 270 nanometers.

The team presents its findings in the May 13 issue of the British journal Nature.

"Looking some years ahead, it doesn't seem unrealistic to expect commercial applications of entangled photons in secure data transmission, in high-resolution optical readout and storage systems," quantum optics researcher Dirk Bouwmeester, at the University of California, Santa Barbara, wrote in an accompanying commentary in Nature. "As if the world isn't entangled enough!"

Scientists over the past decade have dreamed of using entangled photons in secure data transmission, since their separated components can create communications links that cannot be intercepted.

Super-photons also could help etch tinier features in circuitry, "which could then be used to make faster computer chips with more memory," Jonathan Dowling, principle scientist and supervisor at NASA's Jet Propulsion Laboratory's quantum computing technologies group in Pasadena, Calif., told UPI.

In principle, scientists can get even better resolution by entangling more photons. Physicist Philip Walther and colleagues at the University of Vienna revealed in another Nature article they have entangled up to four.

"At this point, nobody's ever produced more than five single photons at a time in such a way that they knew they had five photons," Mitchell said.

Creating single photons is an incredibly delicate procedure. A single photon produces 10 billion-billion times less light than a 100-watt lightbulb.

"Here it took a heroic effort to get to just three, so scaling up is likely to be very hard," Dowling said.

Ideally, he said "one would like to entangle very many photons, thousands(for sensors). However, for the lithography application, three already is super and useful."

Mitchell said scientists still need better sources of single photons, as well as better detectors of single photons, to help to bring this technology to fruition.

"The sensor applications are likely 20 years or more off, but the quantum imaging -- lithography -- applications could be in five years or so," Dowling noted.

"You could definitely say there may be applications to optical technologies like CD or DVD players, as long as it's added that we're not there yet," Mitchell said. "We've provided one piece of the puzzle, but there are several very important pieces still missing."

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