Imperfect Phase-Randomisation and Generalised Decoy-State Quantum Key Distribution

Abstract

Decoy-state methods [1-3] are essential to perform quantum key distribution (QKD) at large distances in the absence of single photon sources. However, the standard techniques apply only if laser pulses are used that are independent and identically distributed (iid). Moreover, they require that the laser pulses are fully phase-randomised. However, realistic high-speed QKD setups do not meet these stringent requirements [4]. In this work, we generalise decoy-state analysis to accommodate laser sources that emit imperfectly phase-randomised states. We also develop theoretical tools to prove the security of protocols with lasers that emit pulses that are independent, but not identically distributed. These tools can be used with recent work [5] to prove the security of laser sources with correlated phase distributions as well. We quantitatively demonstrate the effect of imperfect phase-randomisation on key rates by computing the key rates for a simple implementation of the three-state protocol.

References in corpus (3)

• Post-selection technique for quantum channels with applications to quantum cryptography
• Discrete-phase-randomized coherent state source and its application in quantum key distribution
• Evaluation of the phase randomness of the light source in quantum key distribution systems with an attenuated laser

Cited by in corpus (12)

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• Security framework for quantum key distribution with imperfect sources
• Quantum key distribution with imperfectly isolated devices
• Improved Decoy-state and Flag-state Squashing Methods
• Quantum Key Distribution with Basis-Dependent Detection Probability
• Finite-size analysis of prepare-and-measure and decoy-state QKD via entropy accumulation
• A consolidated and accessible security proof for finite-size decoy-state quantum key distribution
• Evaluation of quantum key distribution systems against injection-locking attacks
• Imperfect detectors for adversarial tasks with applications to quantum key distribution
• Quantum Key Distribution with Imperfections: Recent Advances in Security Proofs
• Incorporating device characterization into security proofs
• Security proofs for practical QKD: variations, techniques, gaps, and limitations