Atoms teleported by U.S., Austrian teams

By CHARLES CHOI, United Press International  |  June 16, 2004 at 5:14 PM
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NEW YORK, June 16 (UPI) -- Two separate research teams have demonstrated teleportation of information using atoms for the first time, scientists reported Wednesday.

The novel trick someday could help information flow inside quantum computers, machines that in theory can run more calculations in an instant than there are atoms in the universe.

The first thought that often comes to mind concerning teleportation is the so-called beaming of people between distant places, as popularized in the "Star Trek" television series and movies. In teleportation as physicists talk about it, however, properties of a speck of matter or energy, called its quantum states -- such as its energy level, motion or magnetic field -- are transferred from one physical point to another without benefit of physical forces. Under such circumstances, for all intents and purposes, that speck has teleported.

"You take away the identity of a particle and create this identity in a different place with another particle of the same kind," quantum physicist Rainer Blatt at the University of Innsbruck in Austria told United Press International. "One transfers the information and restores it in another place on another atom of the same kind which cannot be distinguished, aside from its position, from the original one."

Initial experiments with teleportation, from 1997 onward, involved quantum states of beams of light. Blatt and colleagues, as well as a team of physicists headed by David Wineland at the National Institute of Standards and Technology in Boulder, Colo., teleported quantum states of atoms.

Both teams report their findings separately in the June 17 issue of the British journal Nature.

Both teams used ions, or electrically charged atoms. Wineland's group used beryllium, while Blatt's used calcium. The ions were trapped and had their motions suspended as much as possible, to make it easier to manipulate them.

In the infinitesimal realm of atoms, the strange laws of quantum mechanics hold sway. One is called entanglement, which states that no matter how far apart two entangled objects are, by looking at one you know exactly what the other is doing.

First, both teams entangled a pair of ions. Roughly speaking, the atoms were hit with laser pulses, such that each prodded the other, intermingling.

Next, the scientists took an ion they wanted to teleport, and measured its quantum states and that of one of the entangled atoms. The results were then sent to the location of the other entangled atom, and used to transform it into the ion the scientists wanted to teleport.

Normally, measuring the quantum states of an atom requires a tremendous amount of information, while any measurement of the atom alters it, yielding, at most, just one bit of data.

"In this idea of teleportation, we only needed to send just two bits of classical information," Wineland told UPI. Using just that, they recreated the atom they wanted for teleportation.

Teleportation of quantum states from items more complicated than atoms -- such as molecules or even more complex objects like humans -- "seems out of reach currently, since it is not known how to handle such an enormous amount of complex information, how to prepare the required entangled states and how to do this in a reasonable amount of time," Blatt said. "The future potential will not be like beaming in Star Trek."

Instead, both Wineland and Blatt said teleportation someday could help build revolutionary "quantum computers." The devices take advantage of the bizarre phenomenon quantum theory calls superposition, in which objects such as electrons or atoms can exist simultaneously in two places or spin in two opposite directions at the same time.

Modern computers work by symbolizing information as a series of ones and zeros -- binary digits known as bits. This code is conveyed via transistors -- minute switches that can be either flicked on or off to represent a one or a zero. However, computers built using superposition could exhibit what are called quantum bits, which exist in both on-and-off states simultaneously.

Quantum computers, therefore, can run every possible on-off combination at once, making them dramatically faster than conventional devices when it comes to solving certain mathematical problems.

"If we had a quantum computer, we could crack the most common type of encoding used," Wineland said.

The enormous potential of quantum computing is attracting research interest at university and national research labs alike, and at industrial giants such as AT&T, IBM, Hewlett-Packard, Lucent and Microsoft.

Spies and military organizations around the world likewise are investigating quantum computers. For example, Wineland team's research was supported in part by the U.S. National Security Agency and the Advanced Research and Development Activity, the U.S. intelligence community's center for conducting advanced R&D related to information technology.

"On the scientific side, people are hoping these quantum computers will allow us to do computations to handle much more difficult physics problems that can't be handled with ordinary computers," Wineland said.

Jeff Kimble, a physicist at the California Institute of Technology in Pasadena, who did not participate in either study, said teleportation should prove essential to quantum computers.

"For example, if entangled particles were distributed throughout various sectors of a quantum computer, then quantum teleportation could provide a means for distant quantum bits, or qubits, to interact without the requirement of physical proximity -- effectively, quantum wiring," he explained.

One advantage of using atoms for teleportation in quantum computers -- as opposed to beams of light -- is atoms can remain in superposition longer. Wineland said his team confined beryllium atoms in superposition for 10 minutes, while superposition has been achieved in beams of light so far for only "significantly less than a second," he said.

Quantum computers remain quite far away from realization, Wineland cautioned. "The right unit of time is the decade -- choose your number of decades."

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Charles Choi covers research and technology for UPI Science News. E-mail sciencemail@upi.com

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