Investigating the impact of clock frequency stability on practical quantum key distribution.

Area of Science:

• Quantum Information Science
• Quantum Communication Systems
• Cryptography and Security

Background:

• Qubit-based synchronization simplifies quantum key distribution (QKD) systems.
• System performance relies on accumulating qubit events, making it vulnerable to clock frequency instability, particularly under high channel loss.

Purpose of the Study:

• To investigate the impact of non-ideal oscillator frequency instability on QKD performance.
• To analyze clock drift-induced deterioration in lossy quantum communication channels.
• To provide a model for evaluating and optimizing QKD synchronization subsystems.

Main Methods:

• Simulated QKD key generation rates considering optimal acquisition times and varying channel loss.
• Experimental validation using QKD systems with different clock configurations.
• Analysis of clock drift effects on synchronization accuracy and key rates.

Main Results:

• Clock frequency instability significantly impacts QKD performance under high channel loss.
• Secure key generation was experimentally confirmed up to 67 dB channel loss.
• The proposed model accurately predicts performance degradation due to clock drift.

Conclusions:

• Qubit-based synchronization in QKD is susceptible to clock drift, especially in lossy environments.
• Despite challenges, reliable secure key generation is achievable even with significant channel loss (up to 67 dB).
• The developed model serves as a valuable tool for optimizing quantum communication synchronization.