Using Cascade in Quantum Key Distribution

Abstract

We point out a critical flaw in the analysis of Quantum Key Distribution (QKD) protocols that employ the two-way error correction protocol Cascade. Specifically, this flaw stems from an incom-plete consideration of all two-way communication that occurs during the Cascade protocol. We present a straightforward and elegant alternative approach that addresses this flaw and produces valid key rates. We exemplify our new approach by comparing its key rates with those generated using older, incorrect approaches, for Qubit BB84 and Decoy-State BB84 protocols. We show that in many practically relevant situations, our rectified approach produces the same key rate as older, incorrect approaches. However, in other scenarios, our approach produces valid key rates that are lower, highlighting the importance of properly accounting for all two-way communication during Cascade.

References in corpus (4)

• Distillation of secret key and entanglement from quantum states
• Quantum key distribution over 122 km of standard telecom fiber
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Cited by in corpus (4)

• Efficient Information Reconciliation for High-Dimensional Quantum Key Distribution
• Harnessing high-dimensional temporal entanglement using limited interferometric setups
• Quantum Key Distribution with Imperfections: Recent Advances in Security Proofs
• Security proofs for practical QKD: variations, techniques, gaps, and limitations