'Building block' of quanutm networks created

Feb 07, 2013
'Building block' of quanutm networks created
A scanning electron microscope image of one of the quantum photonic devices andrei faraon and his colleagues created. It features a micro-ring resonator coupled to a waveguide. Credit: Faraon/Caltech

(Phys.org)—A proof-of-concept device that could pave the way for on-chip optical quantum networks has been created by a group of researchers from the US.

Presenting the device today, 8 February, in the Institute of Physics and German Physical Society's , it has been described as the "building block of future ."

In an optical quantum network, information is carried between points by photons – the basic unit of light. There is a huge potential for this type of network in the field of and could enable computers that are millions of times faster at solving certain problems than what we are used to today.

This new device, which combines a single nitrogen-vacancy centre in diamond with an optical resonator and an optical waveguide, could potentially become the memory or the processing element of such a network.

A nitrogen-vacancy centre is a defect in the of diamond where one of the is replaced by a and the nearest neighbour carbon atom is missing. The nitrogen-vacancy centre has the property of photoluminescence, whereby a substance absorbs photons from a source and then subsequently emits photons.

The emitted photons are special in that they are correlated, or entangled, with the nitrogen-vacancy centre that they came from, which as the researchers state is crucial for future experiments that will look to examine this correlation. You cannot get these correlated photons from a normal light source.

In this device, the photons are produced from a nitrogen-vacancy centre within a diamond microring resonator. The nitrogen-vacancy centre is located inside the diamond resonator as it is more likely to emit photons than when it is located in the waveguide or just in plain diamond. Moreover, the photons emitted in the resonator are easier to couple into an on-chip waveguide.

The cotton bud-shaped waveguide sends the photons out into a desired direction through at either end.

"One of the holy grails in quantum photonics is to develop networks where optical quantum emitters are interconnected via photons," said lead author of the study Andrei Faraon.

"In this work we take the first step and demonstrate that photons – the information carriers – from a single nitrogen-vacancy centre can be coupled to an and then further coupled to a photonic waveguide. We hope that multiple devices of this kind will be interconnected in a photonic network on a chip."

The study, undertaken by researchers from the California Institute of Technology, Hewlett Packard Laboratories and University of Washington, tested the device by cooling it to temperatures below 10K and shining a green laser onto the nitrogen vacancy to evoke .

The entire device was etched in a diamond membrane that was around 300 nanometres thick.

"The whole idea of these devices is that they are able to be produced en masse. So far the procedure for mass fabrication is still at the proof-of-concept level, so there is still plenty of work to be done to make it reliable," continued Professor Faraon.

Explore further: Physicists discuss quantum pigeonhole principle

More information: "Quantum photonic devices in single crystal diamond," Andrei Faraon et al., New J. Phys. 15 025010, 2013. iopscience.iop.org/1367-2630/15/2/025010/article

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User comments : 4

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robbor
not rated yet Feb 08, 2013
felt like i was just reading Gravity's Rainbow
Neinsense99
3 / 5 (8) Feb 08, 2013
quanutm?
Sonhouse
not rated yet Feb 08, 2013
It looks like the ring stores a photon which flies around the ring for a certain time before it decays too much and then retrieved to become part of a photonic word, you would need one per bit it looks like, so 8 of them would be one byte.
nano quantum
1 / 5 (2) Feb 09, 2013
quantum is sooooooooo cool