Researchers at American Institute of Physics and University of Witwatersrand in South Africa now review the progress being made in using structured light in quantum protocols to create a larger encoding alphabet, stronger security and better resistance to noise. Structured light is a fancy way to describe patterns or pictures of light, but deservedly so as it promises future communications that will be both faster and more secure.
Since patterns of light can be distinguished from each other, they can be used as a form of alphabet.
Traditionally, quantum protocols have been implemented with the polarization of light, which has only two values — a two-level system with a maximum information capacity per photon of just 1 bit. But by using patterns of light as the alphabet, the information capacity is much higher. Also, its security is stronger, and the robustness to noise (such as background light fluctuations) is improved. (ScienceDaily)