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Chinese physicists set new record for teleportation

May 12, 2012 1:56pm
In a development that could have significant implications for secure communications, Chinese physicists have set a new record for teleportation, beaming photons over a distance of some 100 kilometers.

The Massachusetts Institute of Technology's "Technology Review" said the feat was established by a Chinese team that teleported entangled photons over 97 km across a lake in China.

"That's an impressive feat for several reasons. The trick these guys have perfected is to find a way to use a 1.3 Watt laser and some fancy optics to beam the light and receive it," it said.

It said the team included Juan Yin and colleagues at the University of Science and Technology of China in Shanghai.

According to Technology Review, photons can get lost and entanglement is destroyed in such a process.

While imperfections in the optics and air turbulence account for some of these losses, the biggest problem is beam widening.

"Since the beam spreads out as it travels, many of the photons simply miss the target altogether," it noted.

Thus, it said the most important advance these researchers have made is to develop a steering mechanism using a guide laser that keeps the beam precisely on target.

"As a result, they were able to teleport more than 1,100 photons in four hours over a distance of 97 km," it said.


Technology Review noted teleportation is the extraordinary ability to transfer objects from one location to another without traveling through the intervening space.

It said the idea is not that the physical object is teleported but the information that describes it.

This can then be applied to a similar object in a new location which effectively takes on the new identity.

"And it is by no means science fiction. Physicists have been teleporting photons since 1997 and the technique is now standard in optics laboratories all over the world," it said.

The phenomenon that makes this possible is known as quantum entanglement, a deep and mysterious link that occurs when two quantum objects share the same existence and yet are separated in space.

On the other hand, it said teleportation can be extremely useful in communications, as teleported information does not travel through the intervening space, and cannot be secretly accessed by an eavesdropper.

"For that reason, teleportation is the enabling technology behind quantum cryptography, a way of sending information with close-to-perfect secrecy," it said.

But entangled photons are fragile objects and cannot travel further than 1 km or so down optical fibers because the photons end up interacting with the glass breaking the entanglement.

Physicists have had more success teleporting photons through the atmosphere, it added.

In 2010, a Chinese team said it had teleported single photons over a distance of 16 km - "handy but not exactly Earth-shattering."

But with the recent development, Technology Review said these researchers may have an eye on the possibility of satellite-based quantum cryptography which would provide ultra secure communications around the world.

"That's in stark contrast to the few kilometers that are possible with commercial quantum cryptography gear," it said.

"Of course, data rates are likely to be slow and the rapidly emerging technology of quantum repeaters will extend the reach of ground-based quantum cryptography so that it could reach around the world, in principle at least," it added.

But a perfect, satellite-based security system might be a useful piece of kit to have on the roof of an embassy or distributed among the armed forces, it added. — LBG, GMA News
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