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Quantum teleportation approaches the computer chip

Researchers transmit information from one tiny circuit to another

QUANTUM VIEW  An ant provides scale in this false-color electron micrograph of the first solid-state device capable of quantum teleportation.

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Quantum teleportation is on its way to becoming routine. New work demonstrates that quantum information can teleport on demand, using for the first time a device that closely resembles a computer chip.

The techniques laid out in two new studies are major steps toward developing quantum computers and ensuring secure communication over quantum networks, says physicist Eugene Polzik of the University of Copenhagen, who was not involved in either study.

Unlike Star Trek’s transporters, quantum teleportation does not physically transport objects. Instead it shuttles information about the properties of an object and incorporates those properties into a new object. For a simple particle like a photon, that’s just as effective as moving it: A photon that has the same polarization, energy and other attributes as another photon might as well be the same photon.

Quantum teleportation is not easy to accomplish because the properties of quantum particles are so fragile. A sender can’t simply measure a particle and share those properties with a receiver because the act of measuring changes the particle. In 1997 physicists developed a technique that achieved quantum teleportation, at least occasionally — a very small percentage of the desired information actually got transported. Since then physicists have successfully teleported photons over increasing distances through fiber-optic cables (SN: 6/30/12, p. 10), but the process remains inconsistent.

Now physicist Andreas Wallraff at ETH Zurich and his team have created the first solid-state device, similar to a computer chip, that is capable of teleporting quantum information. The chip contains tiny circuits that each behave like an atom. The circuits are connected by millimeters-long transmission lines carrying microwave radiation, which entangles the circuits so that the properties of one affect the other. By programming a bit of quantum information into circuit A, Wallraff and his team changed the signal arriving at circuit B. They could then use that changed signal to determine the original properties of circuit A and transfer them to circuit B.

Most importantly, Wallraff’s teleportation system successfully transports information in nearly every attempt, and it can do it roughly 10,000 times per second, an unprecedented rate. The study appears in the Aug. 15 Nature.

In another study in the same issue, an international team led by physicist Akira Furusawa of the University of Tokyo successfully transported information between photons with near-perfect success, or 50 times as efficient as previous experiments. Polzik says such a technique could be pivotal for quantum computers.

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