Paths in quantum communication networks

The performances of point-to-point quantum protocols is strongly dependent on the nature of the quantum channel and it rapidly deteriorates with distance. Well-known fundamental and practical limitations prevent to achieve simultaneously high rates, long distances and unconditional security. In this scenario, the rate of quantum communications between users placed at arbitrary points of a quantum communication network will strongly depend on the structure of the network, on its extension and on the nature of the communication channels. Purpose of the present work is to develop a theoretical framework to understand how the properties of the underlying network influence the rate and security of quantum communications and illustrate a potential strategy of network optimization.This work is part of the activities of the PON project "Development of quantum systems and technologies for IT security in communication networks" (QUANCOM) which aims to the realization of a metropolitan quantum communication network through the collaboration between universities, research centers and companies operating in the communication market area.