In our days, computing devices slowly reach their computational limits, since the circuit units cannot be reduced significantly with modern technology. However, there are growing number of telecommunications and IT problems which need a solution. A solution to these problems could be the quantum computing. It is based on the laws of quantum mechanics and works with mainly atomic-scale elements and offers new and unusual opportunities for the classical world.
Quantum Key Distribution (QKD) is one of the most discussed topics of quantum computing. QKD is a method, which is demonstrably safe and assists to create private keys between two communicating parties on a public channel. These keys have great role in the secure communications, because a classical symmetrical encryption system could be built with their assist. I studied the BB84 and the Ekert91 protocols, which are very important QKD protocols.
With global quantum key distribution networks we can bridge enormous distances, thus facilitating communication between two ground stations. There are several feasible scenarios for these networks.
In my work, I compared the operation of two scenarios of these networks using the quantum bit error rate calculations of the Ekert91 protocol. I carried out developments on a Java-based simulation framework to perform the analysis of the protocol. In my research, I considered the characteristics of free-space quantum based communication (e.g., weather conditions, environmental influences), and calculated with different orbit heights and airline distances.