Scientists turn nanodiamonds into controlled light sources

A research group from the St. Petersburg National Research University of Information Technologies, Mechanics and Optics (ITMO) has developed a first-of-its-kind controlled light source based on a nanoscale diamond crystal. The experiments have shown that the presence of a diamond crystal practically doubles the intensity of the light emitted by such a source and allows it to be controlled without the need for additional nanostructures. The key to all this is artificially created defects in the crystal structure of diamond, and this technology can be used to create future quantum computers and communication optical networks. Research in the f
ield of modern nanophotonics is conditionally divided into two directions – the creation of active dielectric nanoantennas and the creation of controlled sources. photons. As a basis for nanoantennas, metal particles are usually used on the surface of which plasmons are actively generated. However, the high level of optical loss and heating of metals during operation force scientists to look for alternative options. Therefore, scientists from ITMO have been actively exploring the possibility of using dielectric materials in nanophotonics, they have already successfully created nanoantennas from silicon
and perovskites. Nanodiamonds, due to their tiny size, have some amazing properties. Diamond itself has a very high refractive index of light, high thermal conductivity and low reactivity. And if defects called nitrogen vacancies are artificially created in a diamond, then such a crystal acquires additional properties. A nitrogen vacancy (NV) occurs where one carbon atom is replaced by a nitrogen atom. The direction of rotation of the remaining free electron is easy to control with the help of light and, thanks to this, the vacancy can be used as a quantum bit, a qubit capable of storing quantum information. Scientists from I
TMO have determined that the level of light emitted by a nanodiamond can be increased by combining the luminescence spectrum of the NV center with the frequency of optical resonance of the nanocrystal itself. This can be achieved by placing a vacancy in a strictly defined place and giving the crystal itself a special sh
ape. “Usually a complex system of optical resonators is used to amplify the flux of emitted light,” the researchers write, “We managed to obtain a similar effect without using any additional elements … At the same time, we managed to practically double the speed of controlling the operation of the light source, using only the usual laws of p
hysics. “Scientists conducted their experiments with crystals in which there were several nitrogen vacancies. But their theoretical calculations have shown that a crystal in which only one nitrogen vacancy will be present will work as a highly efficient and controllable source of single photons, which can become an active element of photonic logic elements and other devices.