EFFICIENCY OF THE QUANTUM KEY DISTRIBUTION SYSTEMS - A COMPARATIVE STUDY OF BB84 PROTOCOL WITH ITS IMPROVED VERSIONS

The efficiency of quantum key distribution systems plays an important role in deciding the feasibility of practical quantum cryptographic systems. BB84, the first quantum protocol for key distribution, proposed by Charles Bennett and Gilles Brassard in 1984, allows two remote parties to create and share a secret key with approximately 25% efficiency. There are two remarkable methods that improve essentially the efficiency of the BB84 protocol. First method involves the assignment of significantly different probabilities to the different polarization bases during both transmission and reception of the photons. The second method uses the quantum memory, a device to store the received photons. The paper simulates the two methods using C# applications and performs a statistical analysis by comparing them with the original BB84 protocol.