Wednesday, May 26, 2010

Will Star Trek-style beam-up become reality from sci-fi?

Hong Kong: hinese scientists have pushed the frontiers of science by breaking the record for “quantum teleportation”, the applied physics technology that, in the science fiction writer’s imagination, allowed Star Trek’s captain Kirk to be “beamed up” to his spaceship.

A team of scientists at the University of Science and Technology of China and the premier Tsinghua University in Beijing successfully streamed quantum information between photons over 16 km, much farther than the earlier record of a few hundred meters, the researchers claimed in their report, published last week.

Although peer scientists state emphatically that a Star Trek-inspired teleportation of objects and persons remains firmly in the realm of fantasy, they acknowledge the significance of the latest development as a “giant leap” in quantum teleportation. The same technology, when perfected, could be applied, for instance, in devising encryption methods that are hack-proof, in electronic voting, and in failsafe electronic banking.

The fact that the quantum information between photons was teleported over a distance of 16 km, which is greater than the effective ‘thickness’ of the aerosphere, means that the results could be invoked to facilitate experiments between, for instance, a ground station and a satellite.

In their report on the findings of the project, supervised by Peng Cheng-Zhi and Pan Jian-Wei, the scientists said, “Our result confirms the feasibility of space-based experiments, and is an important step towards quantum-communication applications on a global scale.”

Although it’s called “quantum teleportation”, scientists say there is no physical teleportation of any object: what happens, instead, is that two photons or ions are ‘entangled’ — that is, connected by an invisible ‘umbilical cord’ — in such a way that when the quantum state of one is altered, the state of the other (which is physically separate) is also altered.

Thus, information is “teleported” between the two without using signals or networks.

In earlier experiments, the photons were made to travel in ‘fibre channels’ to preserve their state, but the Chinese scientists said they “maximally entangled” two photons and sent the one with higher energy through a 16-km-long ‘free space channel’.
The teleportation site was located at Badaling, familiar to most tourists to Beijing as one of the sites to access the Great Wall of China; the receiver was sighted at Huailai in nearby Hebei province. “The straight-line distance between the two stations is about 16km,” the scientists said.

Although excitingly path-breaking, the experiment is still to be perfected: the average fidelity of the teleportation achieved was 89%; that was well above the classical limit of 66% achieved hitherto, but is still short of the 100% fidelity that scientists require.

Quantum teleportation was first postulated in 1993 by Charles Bennet, an IBM researcher. But it was “brought to life’ by Nicolas Gisin, at the University of Geneva, who demonstrated teleportation. The unearthly application potential of this technology —as envisioned by science fiction fantasists — has led it to be branded a kind of ‘voodoo’ experiment — or an optical illusion worthy of PC Sorcar.

Even noted scientist Albert Einsten remained sceptical of quantum entanglement, calling it “remote-controlled spooky action”.

Today, however, a quiver of excitement runs through the entire scientific community — as if they were all “maximally entangled” photons being subjected to a “quantum teleportation” experiment worthy of a space-age fantasy and who can’t wait to be “beamed up” into the future.