Defects in diamonds used to create photons for the quantum internet

Physicists from the Humboldt University in Berlin have generated and detected photons from

stable frequencies emitted by nitrogen-substituted vacancies in diamond nanostructures. The technology is suitable for the development of the quantum Internet.

Scientists have integrated individual qubits (quantumbits) into optimized diamond nanostructures. They are a thousand times thinner than a human hair and allow the directed transmission of emitted photons through optical fiber.

NV center or nitrogen-substituted vacancy is onefrom diamond defects, which arises when a carbon atom is removed from the crystal lattice and the resulting vacancy binds to nitrogen. In previous studies, scientists have shown that such vacancies can be used as a source of single photons. 

But in the manufacture of nanostructures, the surfacematerial is damaged at the atomic level, and free electrons create uncontrolled noise for the generated light particles. It causes photon frequency fluctuations, preventing successful quantum operations such as entanglement.

To overcome this limitation, researchersused a diamond material with a relatively high density of nitrogen atoms in the crystal lattice. The study showed that it is possible to generate photons with stable frequencies in such a material. Although the physics of this process is not completely understood and requires further study, scientists believe that a large number of nitrogen-substituted vacancies protect the quantum light source from electronic noise on the surface of the nanostructure.

To ensure data transmission with acceptablecommunication speeds over long distances in a quantum network, all photons must be collected in optical fibers and transmitted without loss. At the same time, they should all have the same color (the same frequency). The study confirms the ability to transmit data without noise. Moreover, with the help of this technology, the current communication speeds between distributed quantum systems can be increased by more than 1,000 times in the future.

Read more:

A red halo flared up over Italy. Now its nature has been explained

Named a way to reduce appetite without surgery

Chia seed experiment confirms Alan Turing's famous mathematical model

On the cover: An artistic illustration of the use of defects in diamonds to generate single photons. Image: HU Berlin, AG Integrierte Quantenphotonik