Defective diamonds could be quantum computing's best friend

Harvard, University at Buffalo cite breakthroughs that could speed development of quantum computers and networks

University at Buffalo researchers have gained understanding of defects in diamonds that could be used for applications such as quantum information processing.

Quantum computing is an exciting area of research into potentially very fast computers that use quantum mechanics rather than traditional transister-based technology for moving data, in this case dubbed qubits (See: Is Quantum Computing real?)

"We normally want things to be perfect, but defects are actually very important in terms of electronic applications," said Peihong Zhang, the UB associate professor of physics who led the study. "There are many proposals for the application of defective diamonds, ranging from quantum computing to biological imaging, and our research is one step toward a better understanding of these defect systems."

The researchers have gained insights into how electrons rise to an excited state within a vacancy in a defective diamond -- information that could be used for developing quantum computers with stable data transmission properties (more details here).

UAB researchers, exploiting the school's supercomputing facility, are working with colleagues at Rensselaer Polytechnic Institute in Troy, N.Y. Their research is funded by the Department of Energy.

Separately, Harvard researchers "have managed to capture light in tiny diamond pillars embedded in silver, releasing a stream of single photons at a controllable rate," according to the school.

"We can make the emission of photons faster, which will allow us to do more processing per second-for example, more computations-in the future quantum network," says principal investigator Marko Lončar, associate professor of Electrical Engineering at the Harvard School of Engineering and Applied Sciences.The finding was published in Nature Photonics, appearing online Oct. 9.

Researchers led by Marko Lončar at SEAS have managed to control the rate of emission of photons from diamond nanoposts, an important advance toward quantum computing.

According to Harvard:

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 research has been funded by the Department of Defense, DARPA, the NSF, the King Abdullah University of Science and Technology, the Sloan Foundation and Harvard's Nanoscale Science and Engineering Center.

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