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Experimental demonstration of a quantum key distribution without signal disturbance monitoring


In existing quantum key distribution protocols, two legitimate peers, Alice and Bob, must monitor the signal disturbance to place a bound on the potential information leakage. However, in the round-robin differential phase shift (RRDPS) protocol, monitoring of the signal disturbance is unnecessary. Here, we present the first active implementation of the RRDPS protocol. In our experiment, Alice prepares packets of pulses, where each packet is a train with 65 pulses and the global phase of each packet is randomized. Bob uses a novel actively controlled variable-delay interferometer to realize the random switching of different delays. Benefiting from the large pulse number of each packet, and the high stability and low insertion loss of the interferometer, the system can distribute a secret key over a distance of 90 km. Our experimental demonstration and results confirm the feasibility of the RRDPS protocol, particularly in high-error situations.

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Figure 1: Experimental set-up for the RRDPS QKD system.
Figure 2: Parameters of each delay of the variable-delay interferometer.
Figure 3: Numerical simulation and experimental results.
Figure 4: Secret key rates versus error rate (20 km transmission distance).

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The authors thank J.-D. Wang and J.-Z. Huang for scientific discussions. This work was supported by the National Natural Science Foundation of China (grant nos. 61475148, 61201239, 61205118 and 11304397), the National Basic Research Program of China (grant nos. 2011CBA00200 and 2011CB921200) and the Strategic Priority Research Program (B) of the Chinese Academy of Sciences (grant nos. XDB01030100 and XDB01030300).

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Authors and Affiliations



S.W. and Z.-Q.Y. contributed equally to this work. S.W., Z.-Q.Y., W.C., G.-C.G. and Z.-F.H. conceived and designed the experiments. S.W., W.C. and X.-T.S. designed the variable-delay interferometer. S.W., D.-Y.H. and Z.Z. designed the control and detection parts of the system. Z.-Q.Y., W.C. and L.-J.Z. designed the software. All authors performed the experiments. Z.-Q.Y. and H.-W.L. performed the simulation and analysed the data. S.W., Z.-Q.Y., W.C. and Z.-F.H. wrote the paper.

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Correspondence to Wei Chen or Zheng-Fu Han.

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The authors declare no competing financial interests.

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Wang, S., Yin, ZQ., Chen, W. et al. Experimental demonstration of a quantum key distribution without signal disturbance monitoring. Nature Photon 9, 832–836 (2015).

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