Sending-or-Not-Sending Twin-Field Quantum Key Distribution with a Passive Decoy-State Method

Area of Science:

• Quantum Information Science
• Quantum Cryptography
• Quantum Communication

Background:

• Twin-field quantum key distribution (TF-QKD) offers enhanced rate-distance limits without quantum repeaters.
• Sending or not-sending quantum key distribution (SNS-QKD), a TF-QKD variant, improves security and tolerates misalignment errors.
• Current SNS-QKD relies on active decoy-state methods, posing risks of side-channel information leakage.

Purpose of the Study:

• To propose a novel passive decoy-state SNS-QKD protocol.
• To enhance the security of SNS-QKD by mitigating side-channel vulnerabilities.
• To maintain the advantageous error tolerance of SNS-QKD.

Main Methods:

• Development of a passive decoy-state strategy for SNS-QKD.
• Theoretical analysis of the proposed protocol's security.
• Numerical simulations to evaluate performance and security enhancements.

Main Results:

• The passive decoy-state SNS-QKD protocol significantly improves source security.
• The protocol successfully retains the ability to tolerate large misalignment errors.
• Simulations confirm enhanced security without compromising practical advantages.

Conclusions:

• The proposed passive decoy-state SNS-QKD protocol offers a more secure implementation.
• This advancement addresses practical security concerns in SNS-QKD systems.
• The protocol provides valuable insights for the future deployment of SNS-QKD.