Loss-tolerant quantum cryptography with imperfect sources

Understand

In principle, quantum key distribution (QKD) offers unconditional security based on the laws of physics.

• In practice, flaws in the state preparation undermine the security of QKD systems, as standard theoretical approaches to deal with state preparation flaws are not loss-tolerant.
• An eavesdropper can enhance and exploit such imperfections through quantum channel loss, thus dramatically lowering the key generation rate.
• Crucially, the security analyses of most existing QKD experiments are rather unrealistic as they typically neglect this effect.