Finite-key analysis for twin-field quantum key distribution based on generalized operator dominance condition

Area of Science:

• Quantum Information Science
• Quantum Cryptography
• Physics

Background:

• Quantum key distribution (QKD) enables secure communication but faces rate-distance limitations.
• Twin-field (TF) QKD overcomes these limits, increasing achievable distances.
• Existing finite-key analysis for TF-QKD is restricted to limited decoy states.

Purpose of the Study:

• To develop an improved finite-key analysis for TF-QKD.
• To overcome limitations of previous analysis methods.
• To enhance secret key rates and approach asymptotic bounds.

Main Methods:

• Devised a new, more general operator dominance condition for finite-key analysis.
• Incorporated a larger number of decoy states into the analysis.
• Theoretically analyzed the impact of increased decoy states on key rates.

Main Results:

• The improved analysis allows for higher secret key rates in TF-QKD.
• The new method approaches the theoretical asymptotic bound.
• The key rate can be further improved by increasing the number of decoy states.

Conclusions:

• The proposed finite-key analysis significantly enhances TF-QKD performance.
• This approach enables higher secret key rates in practical QKD experiments.
• The findings pave the way for more secure and longer-distance quantum communication.