Security Analysis of Quantum Key Distribution with Small Block Length and Its Application to Quantum Space...

Area of Science:

• Quantum Information Science
• Cryptography
• Optical Engineering

Background:

• Real-world quantum key distribution (QKD) security relies on data collection within finite time.
• Current finite-key security analyses necessitate large block lengths (around 10^4 bits).
• Entanglement-based satellite QKD faces challenges due to high channel loss (up to 70 dB).

Purpose of the Study:

• To develop an improved finite-key security analysis for QKD.
• To reduce the block length requirements for practical QKD implementations.
• To assess the feasibility of space-based QKD systems.

Main Methods:

• An enhanced finite-key security analysis was developed.
• The analysis was applied to standard channel and protocol settings.
• The method was used to evaluate the Micius QKD satellite's performance.

Main Results:

• The improved analysis reduces block length requirements by 14% to 17%.
• This reduction can save weeks of measurement time for satellite QKD.
• The Micius satellite can generate positive secret keys with a 10^-5 security level.

Conclusions:

• The enhanced analysis significantly lowers data demands for QKD.
• Space-based QKD systems, like entanglement-based satellite QKD, become more practical.
• This research advances the realization of secure, real-world quantum communication networks.