The world's first photonic router

Jul 14, 2014
Illustration of the photonic router the Weizmann Institute scientists created. At the center is the single atom (orange) that routes photons (yellow) in different directions. Credit: Weizmann Institute of Science

Weizmann Institute scientists have demonstrated for the first time a photonic router – a quantum device based on a single atom that enables routing of single photons by single photons. This achievement, as reported in Science magazine, is another step toward overcoming the difficulties in building quantum computers.

At the core of the device is an atom that can switch between two states. The state is set just by sending a single particle of light – or photon – from the right or the left via an optical fiber. The atom, in response, then reflects or transmits the next incoming photon accordingly. For example, in one state, a photon coming from the right continues on its path to the left, whereas a photon coming from the left is reflected backwards, causing the atomic state to flip. In this reversed state, the atom lets coming from the left continue in the same direction, while any photon coming from the right is reflected backwards, flipping the atomic state back again. This atom-based switch is solely operated by single photons – no additional external fields are required.

"In a sense, the device acts as the photonic equivalent to electronic transistors, which switch electric currents in response to other ," says Dr. Barak Dayan, head of the Weizmann Institute's Quantum Optics group, including Itay Shomroni, Serge Rosenblum, Yulia Lovsky, Orel Bechler and Gabriel Guendleman of the Chemical Physics Department in the Faculty of Chemistry. The photons are not only the units comprising the flow of information, but also the ones that control the device.

This achievement was made possible by the combination of two state-of-the-art technologies. One is the laser cooling and trapping of atoms. The other is the fabrication of chip-based, ultra-high quality miniature optical resonators that couple directly to the optical fibers. Dayan's lab at the Weizmann Institute is one of a handful worldwide that has mastered both these technologies.

This image depicts a complete assembly. Credit: Weizmann Institute of Science

The main motivation behind the effort to develop quantum computers is the quantum phenomenon of superposition, in which particles can exist in many states at once, potentially being able to process huge amounts of data in parallel. Yet superposition can only last as long as nothing observes or measures the system otherwise it collapses to a single state. Therefore, photons are the most promising candidates for communication between quantum systems as they do not interact with each other at all, and interact very weakly with other particles.

This image depicts from left to right Serge Rosenblum, Yulia Lovsky, Orel Bechler and Itay Shomroni. Credit: Weizmann Institute of Science

Dayan: "The road to building quantum computers is still very long, but the device we constructed demonstrates a simple and robust system, which should be applicable to any future architecture of such computers. In the current demonstration a single atom functions as a transistor – or a two-way switch – for photons, but in our future experiments, we hope to expand the kinds of devices that work solely on photons, for example new kinds of quantum memory or logic gates."

Explore further: Scientists track quantum errors in real time

More information: All-optical routing of single photons by a one-atom switch controlled by a single photon, www.sciencemag.org/content/ear… science.1254699.full

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User comments : 10

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George_Rajna
Jul 14, 2014
This comment has been removed by a moderator.
baudrunner
not rated yet Jul 14, 2014
That single atom sets up an oscillation of its own by way of its spin-switching, which is okay if you are only ever playing with a single atom, but in a system this may create issues.
TechnoCreed
1 / 5 (1) Jul 15, 2014
BDS
jessicarosenblum1
not rated yet Jul 25, 2014
PART I

Dear Technocreed

What I've always loved about science is that it seems to stand apart from politics and international disputes. It creates conditions where people of all kinds, nationalities, races and believes can work side by side for the same cause, whether they're Iranian, Israeli, Liechtensteiner, Jewish, Buddhist, Vegan, Black or White. It enthralls me to see countless intelligent people unified by their love of science, a common passion to contribute to society and to broaden the knowledge and understanding of the earth we live on and the whole entire universe around it.
jessicarosenblum1
not rated yet Jul 25, 2014
Then again, since you desperately comb through this website, looking for articles you can comment the 3 only letters you know on, you are not only making the articles more popular by clicking on them, but also acknowledging that Israel is indeed very lucrative for the scientific community

Thank you.
jessicarosenblum1
not rated yet Jul 25, 2014
PART II

Here's another reason why your comment makes me mirthless.
By boycotting this absolutely genius device, you condemn the use of some of my favorite things including USB flash drives, Laser Keyboards, Waze, Viber, Biological pest control, MobileEye's technology, Super iron batteries, Rummikub,
the endoscope, treatments for horrible diseases such as MS and Gaucher's, devices that detect heart attacks and so, so much more.
And if all of the above aren't enough to make you question the logic behind your comment, then please do it for the sake of innocent photonic routers, who don't deserve this hatred.
Or at the very least: stop using flash drives. Since they are, apparently, the devil's invention.

Also, when the quantum computer gets invented, it is your duty to keep holding on to your outdated computer while the rest of us are having the time of our lives.
Sincerely,

Dereck Splinter, fellow scientist
TechnoCreed
not rated yet Jul 25, 2014
Dear Technocreed

What I've always loved about science is that it seems to stand apart from politics and international disputes. It creates conditions where people of all kinds, nationalities, races and believes can work side by side for the same cause, whether they're Iranian, Israeli, Liechtensteiner, Jewish, Buddhist, Vegan, Black or White. It enthralls me to see countless intelligent people unified by their love of science, a common passion to contribute to society and to broaden the knowledge and understanding of the earth we live on and the whole entire universe around it.
If the revolting sight of hundreds of dead Palestinians in the Gaza strip, including kids on the beach and in a U.N. protected school, do not seem to convey any concerns on your behalf, it is not so for the majority of the people around the world. Your shallow rhetoric will not have any influence on that. Israelite has to become wiser at choosing their leaders. The international community is watching and the BDS movement is growing.
In defence of my position, standing behind Steven Hawking, I find myself in pretty good company.

Whydening Gyre
not rated yet Jul 26, 2014
BDS

What is BDS?
TechnoCreed
not rated yet Jul 26, 2014
Boycott, Divestment and Sanctions
Whydening Gyre
not rated yet Jul 26, 2014
Boycott, Divestment and Sanctions

Well, there it is, then...
Science and politics are two sides of the same coin...
TechnoCreed
not rated yet Jul 26, 2014
Boycott, Divestment and Sanctions
Well, there it is, then...
Science and politics are two sides of the same coin...
If there is a moment when a moral judgement should outweigh any previous consideration, the destruction of so many innocent lives should be one of them. It is up to every individual to decide when they had enough and, with the help of the social medias, send a clear message.