June 7th, 2013 by James Ayre
A new milestone has been reached in the development of a practical quantum teleportation system — researchers have for the first time succeeded in the teleportation of information between two separate clouds of gas atoms, over long-distances. And not just once, the method is apparently already extremely reliable — working every single time that it’s been attempted.
It’s been possible for quite some time now to “teleport” information on the quantum level from light to light. And a couple of years back, the same researchers who reached this recent milestone were able to teleport information between between light and gas atoms for the first time. But this new achievement takes that a step further — achieving a very reliable means of gas to gas quantum teleportation over long-distances.
“It is a very important step for quantum information research to have achieved such stable results that every attempt will succeed,” says Eugene Polzik, professor and head of the research center Quantop at the Niels Bohr Institute at the University of Copenhagen.
The new experiments were performed in the labs of the research group, located under the Niels Bohr Institute. It’s setup so that there are two glass containers, each of which contains a cloud of gas — composed of billions of caesium gas atoms.
The press release gets into the specifics:
The two glass containers are not connected to each other, but information is teleported from the one glass cloud to the other by means of laser light. The light is sent into the first glass container and then that strange quantum phenomenon takes place, the light and gas become entangled. The fact that they are entangled means that they have established a quantum link — they are synchronised.
Both glass containers are enclosed in a chamber with a magnetic field and when the laser light (with a specific wavelength) hits the gas atoms, the outermost electrons in the atoms react -like magnetic needles — by pointing in the same direction. The direction can be up or down, and it is this direction that makes up quantum information, in the same way that regular computer information is made up of the numbers 0 and 1.
The gas now emits photons (light particles) containing quantum information. The light is sent on to the other gas container and the quantum information is now read from the light and registered by a detector. The signal from the detector is sent back to the first container and the direction of the atoms’ electrons are adjusted in relation to the signal. This completes the teleportation from the second to the first container.
The research and experiments are done at room temperature, which means that the gas atoms are moving rather rapidly — at a speed of 200 meters per second in the glass container. This creates a problem of sorts — when the atoms bump into the glass wall, they lose the information that they have been encoded with. To address this the researchers applied a rather common-sense, simple and effective solution.
“We use a coating of a kind of paraffin on the interior of the glass contains and it causes the gas atoms to not lose their coding, even if they bump into the glass wall,” says Professor Eugene Polzik. “It sounds like an easy solution, but in reality it was complicated to develop the method. Another element of the experiment was to develop the detector that registers the photons.”
For this, a particularly sensitive detector was developed over time — it’s effective enough at detecting the photons, that, as of now, it has worked every single time.
Obviously though, lab tests are one thing, cost-effective useful application in the world is another. “In the experiment, the teleportation’s range is ½ meter — hardly impressive in a world where information must be transported around the world in no time.”
“The range of ½ meter is entirely due to the size of the laboratory,” states Eugene Polzik. “We could increase the range if we had the space and, in principle, we could teleport information, for example, to a satellite.”
But the range really isn’t that important, the real success of this recent research is with regards to how reliable the new method is — paving the way towards what the researchers think will be the “quantum communication network of the future.”
The new technique was recently detailed in a paper published in the scientific journal Nature Physics.
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