August 21, 2013 - Quantum teleportation
has taken a great leap
forward but without moving through space, so it's less of a leap and more of a, well, teleportation, for lack of a better word.
Quantum research defies easy language. How do you describe jumping from one spot to another without passing through the space between? Quantum theory works outside of space. In the subatomic realm, all the usual metaphors for progress – a "step," a "leap," a "milestone," a "higher level" – have run off to hide in the box with Schrodinger's cat.
Here's the crux of the matter: While most of physics has to follow the same rules – planets and apples are subject to the same laws of motion – all of those rules fall away when you get down to the subatomic level. For instance, these vanishingly small particles can become "entangled." When two particles are entangled, then whatever you do to one particle instantaneously affects its entangled twin, regardless of the distance between them. Whether they're only a millimeter apart or separated by an entire galaxy, if you alter one, its twin feels it.
Recently, researchers at the Swiss Federal Institute of Technology in Zurich (ETHZ) used entanglement to teleport information across a quarter inch. That sounds easy. After all, the internet sends information thousands of miles in fractions of a second. But this time, the information wasn't carried through the intervening space.
"In telecommunications, information is transmitted by electromagnetic pulses. In mobile communications, for example, microwave pulses are used, while in fibre connections it is optical pulses," explained Andreas Wallraff, professor of physics at ETHZ and head of the study, in a press release.
Quantum teleportation, on the other hand, skips the information carrier – the pulse – and sends only pure information, from one entangled particle to another. Once the particles are entangled, giving information to one means the other instantaneously knows it, too.
It's "comparable to 'beaming' as shown in the science fiction series 'Star Trek,' " said Dr. Wallraff. "The information does not travel from point A to point B. Instead, it appears at point B and disappears at point A, when read out at point B."
Teleporting information from one entangled particle to another is, however, a completely different concept from teleporting inanimate physical objects, much less living human beings.
Theoretically, what works at a distance of a quarter-inch should also work over much longer distances. Indeed, other quantum experiments have already demonstrated long-distance teleportation. Last year, Austrian scientists managed to teleport a photon almost 90 miles between the Canary Islands of La Palma and Tenerife. The difference is that they used visible light in an optical system for teleportation, while the ETHZ team teleported information for the first time in a system that consists of electronic circuits.
"This is interesting, because such circuits are an important element for the construction of future quantum computers," said Wallraff.
Quantum computers are still only theoretical, but if engineering catches up with theory, then they could process enormously large datasets with blinding speed. This could make extraordinary things possible – even time travel, at least according to one hypothesis.
Based on their latest experiment, the ETHZ scientists calculated that they could send approximately 10,000 quantum bits per second, which is much faster than most previous teleportation systems. (A quantum bit is a unit of quantum information.)
From here, the ETHZ team wants to increase the distance between their entangled particles. This time they sent a signal across a superconducting circuit, which is like a computer chip. The next step will be sending information from one chip to another, and ultimately, from one quantum processor to another, across great physical distances.
Their success with teleportation constitutes "a solid ground for future progress in quantum information processing and quantum communication," says Wallraff.