Into the quantum internet at the speed of light

Feb 04, 2013
The atom’s quantum information is written onto the polarization state of the photon. Credit: Harald Ritsch

Not only do optical fibers transmit information every day around the world at the speed of light, but they can also be harnessed for the transport of quantum information. In the current issue of Nature Photonics, a research team of Innsbruck physicists led by Rainer Blatt and Tracy Northup report how they have directly transferred the quantum information stored in an atom onto a particle of light. Such information could then be sent over optical fiber to a distant atom.

Thanks to the strange laws of quantum mechanics, quantum computers would be able to carry out certain much faster than conventional computers. Among the most promising technologies for the construction of a quantum computer are systems of single atoms, confined in so-called ion traps and manipulated with lasers. In the laboratory, these systems have already been used to test key building blocks of a future quantum computer. "Currently, we can carry out successful quantum computations with atoms," explain Andreas Stute and Bernardo Casabone, both PhD students at the University of Innsbruck's Institute for . "But we are still missing viable interfaces with which can be transferred over optical channels from one computer to another."

What makes the construction of these interfaces especially challenging is that the laws of don't allow quantum information to be simply copied. Instead, a future – that is, a network of quantum computers linked by optical channels – would have to transfer quantum information onto individual particles of light, known as photons. These photons would then be transported over an link to a distant computing site. Now, for the first time, quantum information has been directly transferred from an atom in an ion trap onto a single photon. The work is reported in the current issue of by a research team led by Tracy Northup and Rainer Blatt.

Quantum networkers

The University of Innsbruck physicists first trap a single calcium ion in an ion trap and position it between two highly reflective mirrors. "We use a laser to write the desired quantum information onto the electronic states of the atom," explains Stute. "The atom is then excited with a second laser, and as a result, it emits a photon. At this moment, we write the atom's quantum information onto the polarization state of the photon, thus mapping it onto the light particle." The photon is stored between the mirrors until it eventually flies out through one mirror, which is less reflective than the other. "The two mirrors steer the photon in a specific direction, effectively guiding it into an optical fiber," says Casabone. The quantum information stored in the photon could thus be conveyed over the optical fiber to a distant quantum computer, where the same technique could be applied in reverse to write it back onto an atom.

Explore further: 'Dressed' laser aimed at clouds may be key to inducing rain, lightning

More information: Stute, A. et al. Quantum-state transfer from an ion to a photon. Nature Photonics 2013. DOI: 10.1038/NPHOTON.2012.358

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User comments : 8

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Noumenon
2.6 / 5 (10) Feb 04, 2013
Oh, boy,... Don't tell me,... this will mean quantum porn .
Whydening Gyre
2.1 / 5 (7) Feb 04, 2013
LOL, Nou. Can't wait...:-)
SethD
3 / 5 (6) Feb 04, 2013
Once they smelled and tasted "free money", high clergy of the Church of Physics just won't give up.
Quantum computing is daydreaming that costs millions already. If not stopped, it will cost billions soon enough.
Whydening Gyre
2.7 / 5 (7) Feb 04, 2013
Quantum computing is daydreaming that costs millions already. If not stopped, it will cost billions soon enough.

If you factor in the "startup" costs - it already does....
antialias_physorg
3 / 5 (6) Feb 05, 2013
If you factor in the "startup" costs - it already does....


Gee - so did any new technology.
According to you we probably shouldn't have invested in buidling the interent? Or coal/oil infrastructure? Or researched nuclear? Or solar energy? Or telephone systems? Or GPS-sattelites? Or built roads? ...

Science is like that: you never know what will work and what won't. It's not engineering. For quantum computers the real possibility exists. And when it works it will be another leap forward.

There are always those that say that no new research is needed/wanted. But if you want to play Luddite then this site (and the internet in general) is not for you.
Sasquash5000
3 / 5 (1) Feb 08, 2013
I'm all for it so long as my bill doesn't make a quantum leap in the process. I just hope that it goes on the government's tab so that it isn't owned by Comcast or any other ISP's, restricting competition and inflating prices, all the while offering the worst customer service of any industry on the planet (that I've dealt with).
Whydening Gyre
1 / 5 (3) Feb 08, 2013
If you factor in the "startup" costs - it already does....


Gee - so did any new technology.
According to you we probably shouldn't have invested in buidling the interent? Or coal/oil infrastructure? Or researched nuclear? Or solar energy? Or telephone systems? Or GPS-sattelites? Or built roads? ...

Science is like that: you never know what will work and what won't. It's not engineering. For quantum computers the real possibility exists. And when it works it will be another leap forward.

There are always those that say that no new research is needed/wanted. But if you want to play Luddite then this site (and the internet in general) is not for you.

How could y have POSSIBLY assumed all that from one totally unbiased statement?!? I simply stated that startup (research)costs already were in play. You need to either grow a little thicker skin, Mr. Sensitive, or see a shrink for that little schizophrenia problem you have developing...
Whydening Gyre
1 / 5 (3) Feb 08, 2013
I'm all for it so long as my bill doesn't make a quantum leap in the process. I just hope that it goes on the government's tab so that it isn't owned by Comcast or any other ISP's, restricting competition and inflating prices, all the while offering the worst customer service of any industry on the planet (that I've dealt with).

Ha! Try T-mobile...

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