Measurement-Device-Independent Quantum Key Distribution over 200 km

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Y-L. Tang, H-L. Yin, S-J.Chen, Y. Liu, W-J. Zhang, X. Jiang, L. Zhang, J. Wang, L-X. You, J-Y. Guan, D- X. Yang, Z. Wang, H. Liang, Z. Zhang, N. Zhou, X. Ma, T-Y. Chen, Q. Zhang, and J-W. Pan
Phys. Rev. Lett. 113, 190501 (2014)

Measurement-device–independent quantum key distribution (MDIQKD) represents a valid alternative for quantum cryptography. It requires fewer assumptions for security than standard prepare-and-measure schemes, while its implementation is less demanding than fully device-independent protocols.

In their work, Tang and co-workers report the first long-distance implementation of MDIQKD. By developing a 75 MHz clock rate fully automatic and highly stable system and superconducting nanowire single-photon detectors with detection efficiencies of more than 40%, they demonstrate the secure implementation of MDIQKD up to distances of the order of 200 km and achieve a secure key rate 3 orders of magnitude higher than previous efforts. These results provide the most advanced demonstration of this technique.