Single-channel 48-Gbit/s DP PSK Y-00 quantum stream cipher transmission over 400- and 800-km SSMF.

Area of Science:

• Quantum Information Science
• Optical Communications
• Cybersecurity

Background:

• Physical layer security is crucial for fiber-optic networks.
• Existing encryption methods can be vulnerable to advanced attacks.
• Quantum phenomena offer novel approaches to secure data transmission.

Purpose of the Study:

• To demonstrate a novel quantum-noise-assisted cipher system for fiber-optic transmission.
• To achieve a record-high product of data rate and transmission distance for secure communication.
• To leverage quantum shot noise for enhanced physical layer security.

Main Methods:

• Developed a symmetric-key direct-data encryption system using signal masking by quantum (shot) noise.
• Implemented 2^16-level phase randomization of quadrature phase-shift keying data signal.
• Achieved a 48-Gbit/s dual polarization Y-00 cipher with 2^18 phase levels.

Main Results:

• Demonstrated a record data rate-distance product of 32,000 Gbit/s·km (40 Gbit/s net rate × 800 km).
• Successfully transmitted the Y-00 cipher over 400-km and 800-km standard single-mode fibers without significant quality degradation.
• Achieved masking of 2^17 phase levels by shot noise.

Conclusions:

• The demonstrated system offers unprecedented security for fiber-optic communications.
• The use of quantum shot noise provides irreducible and unchanged security.
• This technology paves the way for highly secure and high-capacity optical networks.