Detector-device-independent quantum key distribution: Security analysis and fast implementation

• Published in: Journal of applied physics 2016-08, Vol.120 (6)
• Main Authors: Boaron, Alberto, Korzh, Boris, Houlmann, Raphael, Boso, Gianluca, Lim, Charles Ci Wen, Martin, Anthony, Zbinden, Hugo
• Format: Article
• Language: English
• Subjects: OTHER INSTRUMENTATION
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/1.4960093

One of the most pressing issues in quantum key distribution (QKD) is the problem of detector side-channel attacks. To overcome this problem, researchers proposed an elegant “time-reversal” QKD protocol called measurement-device-independent QKD (MDI-QKD), which is based on time-reversed entanglement swapping. However, MDI-QKD is more challenging to implement than standard point-to-point QKD. Recently, an intermediary QKD protocol called detector-device-independent QKD (DDI-QKD) has been proposed to overcome the drawbacks of MDI-QKD, with the hope that it would eventually lead to a more efficient detector side-channel-free QKD system. Here, we analyze the security of DDI-QKD and elucidate its security assumptions. We find that DDI-QKD is not equivalent to MDI-QKD, but its security can be demonstrated with reasonable assumptions. On the more practical side, we consider the feasibility of DDI-QKD and present a fast experimental demonstration (clocked at 625 MHz), capable of secret key exchange up to more than 90 km.