Cambridge, Mass. October 9, 2011 Engineers and physicists at Harvard have managed to capture light in tiny diamond pillars embedded in silver, releasing a stream of single photons at a controllable rate.
The advance represents a milestone on the road to quantum networks in which information can be encoded in spins of electrons and carried through a network via light, one photon at a time.
The finding was published in Nature Photonics, appearing online on October 9.
"We can make the emission of photons faster, which will allow us to do more processing per secondfor example, more computationsin the future quantum network," explains principal investigator Marko Lončar, Associate Professor of Electrical Engineering at the Harvard School of Engineering and Applied Sciences (SEAS).
The device Lončar's research team has built consists of parallel rows of tiny, nanofabricated diamond posts, embedded in a layer of silver, that can each act as a single photon source.
By removing the silver wrapping from their nanostructures, the team was also able to achieve a slower release of photons, which is of interest for probing the dynamics of the quantum system.
The breakthrough takes advantage of imperfections in the diamond's crystal lattice, where carbon atoms are replaced by other elements. To the naked eye, these imperfections can appear as discolorations in the diamond, turning it yellow in the case of nitrogen. Occasionally, there is also a vacancy (missing carbon atom) next to the nitrogen atom.
Each nitrogen-vacancy imperfection can serve as a nearly perfect quantum emitter, capable of emitting red photons one by one, even at room temperature. The technology is a promising candidate for realization of scalable, on-chip quantum networks.
"The color centers in diamond are very interesting as qubits for quantum information processing, where they can be used as memory to store infor
|Contact: Caroline Perry|