Abstract:
Quantum networks allow connecting users through open channels, with security based on laws
of quantum mechanics Quantum key distribution (QKD) allows the distribution of secret keys
through an open channel, where, unlike classical cryptography, the security is assured by the
laws of Physics rather than computational complexity. Long-distance quantum communication
requires quantum repeaters. Quantum repeaters are experimentally challenging to achieve. The
most crucial ingredient is quantum memory, which is needed to store the qubit while preserving
its entanglement. Using trusted nodes instead of a quantum repeater, quantum memories are
not needed, however, security is compromised if any trusted node is compromised. Network
topology decides the protection against compromised nodes. The more compromised nodes
there are, the less secure communication will be. We propose a multi-path quantum network,
whereby adding optimal edge to existing topology raises security. Also, check for the vulner
ability of the network in the presence of compromised nodes. Results show that the level of
protection increases as the number of paths increases. The topology tells us the number of max
imum compromised nodes that the network can bear. In addition, we have thoroughly studied
the quantum key distribution network, being an application of quantum networks.
