Single polarized-photon emitters based on III-nitride pyramidal quantum dots for quantum cryptography

The modern society is reliant on digital communication, at present experiencing an immense expansion, but the communication should also be secure. Based on global needs, there have been significant efforts over the last decades to realize quantum cryptography schemes experimentally. For this purpose, a flow of generated single photons is required to forward the information, where the message by each photon in terms of wavelength and polarization coding, has to be well controlled.
III-nitride semiconductors are efficient light emitters in the blue and UV spectral range, and the results achieved for blue/UV and also white light emitters (LEDs) were awarded with the Nobel prize 2014. By employment of the InGaN/GaN material system to fabricate quantum dots, located on top of m-sized GaN pyramids, photons can be generated from the dots. By an elongated pyramidal concept, the emission of linearly polarized light has been demonstrated, also on the level of single photons. The single photon concept is promising for quantum cryptography applications, which will be elucidated during the STIAS period. The corresponding multi-photon concept, appropriate for multiplexing for enhancement of the digital communication capacity will also be elaborated.