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Updated: Jul 24, 2025
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Generation and Coherent Control of Pulsed Quantum Frequency Combs
Published on: June 8, 2018
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Experimental Quantum Communication Overcomes the Rate-Loss Limit without Global Phase Tracking.
Lai Zhou1, Jinping Lin1, Yuan-Mei Xie2
1Beijing Academy of Quantum Information Sciences, Beijing 100193, China.
Physical Review Letters
|July 7, 2023
Summary
This study introduces a simpler quantum key distribution method that surpasses previous limits for secure communication over long fiber optic cables. It achieves higher secure key rates, enabling real-time secure voice encryption.
Area of Science:
- Quantum Information Science
- Quantum Communication Technology
- Cybersecurity
Background:
- Secure key rate (SKR) in quantum key distribution (QKD) is limited by the rate-loss bound.
- Twin-field (TF) QKD overcomes this but requires complex phase tracking and strong references, adding noise and reducing efficiency.
- Existing QKD implementations face challenges in achieving high secure key rates over long distances.
Purpose of the Study:
- To develop a simpler and more efficient QKD protocol that overcomes the limitations of TF-QKD.
- To achieve higher secure key rates (SKRs) than existing methods for long-distance quantum communication.
- To enable practical applications like live encrypted voice communication.
Main Methods:
- Implementation of a novel measurement-device-independent (MDI) QKD protocol.
- Utilizing asynchronous coincidence pairing for repeater-like communication.
- Testing the protocol over 413 km and 508 km optical fiber links.
Main Results:
- Achieved finite-size SKRs of 590.61 bit/s (413 km) and 42.64 bit/s (508 km), exceeding rate-loss limits by 1.80x and 4.08x, respectively.
- Demonstrated an SKR exceeding 5 kbit/s at 306 km, sufficient for live one-time-pad encryption.
- The new MDI-QKD method proved simpler and more efficient than TF-QKD.
Conclusions:
- The developed MDI-QKD protocol offers a significant advancement in long-distance quantum communication.
- This technology provides higher secure key rates and greater simplicity compared to previous methods.
- The findings pave the way for economical and efficient intercity quantum-secure networks and real-time encrypted communication.
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