High-rate quantum key distribution over 100 km using ultra-low-noise, 2-GHz sinusoidally gated InGaAs/InP avalanche...

Area of Science:

• Quantum Information Science
• Optoelectronics
• Secure Communications

Background:

• Quantum Key Distribution (QKD) offers theoretically unbreakable security.
• Practical QKD systems require efficient and reliable single-photon detectors.
• Previous QKD implementations faced limitations in distance and key rate.

Purpose of the Study:

• To demonstrate QKD over 100 km using InGaAs/InP avalanche photodiodes (APDs).
• To implement the differential phase shift QKD (DPS-QKD) protocol with advanced APDs.
• To evaluate the performance and practical viability of the developed QKD system.

Main Methods:

• Utilized InGaAs/InP avalanche photodiodes (APDs) as single-photon detectors.
• Employed electrically cooled and 2-GHz sinusoidally gated APDs for the DPS-QKD protocol.
• Measured dark count probability and detection efficiency of the single-photon detectors.

Main Results:

• Achieved a secure key rate of 24 kbit/s over 100 km of optical fiber.
• Single-photon detectors exhibited a dark count probability of 2.8 × 10⁻⁸ and 6% detection efficiency.
• Extended the secure key distribution distance to 160 km against general individual attacks.

Conclusions:

• Demonstrated practical and high-performance QKD over extended distances using APD-based single-photon detectors.
• The DPS-QKD system with APDs shows superior performance compared to superconducting single-photon detectors.
• The results pave the way for more secure and long-distance quantum communication networks.