Implementation of quantum key distribution surpassing the linear rate-transmittance bound

Autor: Cheng-Zhi Peng, X. Fang, Hui Liu, Yan-Lin Tang, Mi Zou, Qiang Zhang, Pei Zeng, Lixing You, Xiongfeng Ma, Hao Li, Yu-Ao Chen, Teng-Yun Chen, Hao Chen, Jian-Wei Pan, Yao Xiang, Weijie Wu, Zhen Wang, Ming-Jun Li, Wei-Jun Zhang, Ying-Jie Sheng
Rok vydání: 2020
Předmět:
Zdroj: Nature Photonics. 14:422-425
ISSN: 1749-4893
1749-4885
Popis: Quantum key distribution (QKD)1,2 offers a long-term solution to secure key exchange. Due to photon loss in transmission, it was believed that the repeaterless key rate is bounded by a linear function of the transmittance, O(η) (refs. 3,4), limiting the maximal secure transmission distance5,6. Recently, a novel type of QKD scheme has been shown to beat the linear bound and achieve a key rate performance of $$O(\sqrt{\eta })$$ (refs. 7–9). Here, by employing the laser injection technique and the phase post-compensation method, we match the modes of two independent lasers and overcome the phase fluctuation. As a result, the key rate surpasses the linear bound via 302 km and 402 km commercial-fibre channels, over four orders of magnitude higher than existing results5. Furthermore, our system yields a secret key rate of 0.118 bps with a 502 km ultralow-loss fibre. This new type of QKD pushes forward long-distance quantum communication for the future quantum internet. Phase-matching quantum key distribution is implemented with a 502 km ultralow-loss optical fibre. The fluctuations of the laser initial phases and frequencies are suppressed by the laser injection technique and the phase post-compensation method.
Databáze: OpenAIRE
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