Long-distance continuous-variable measurement-device-independent quantum key distribution with discrete modulation

Abstract

We propose a long-distance continuous-variable measurement-device-independent quantum key distribution (CV-MDI-QKD) protocol with discrete modulation. This kind of discrete-modulated schemes have good compatibility with efficient error correction code, which lead to higher reconciliation efficiency even at low signalto-noise ratio (SNR). Security analysis shows that the proposed protocol is secure against arbitrary collective attacks in the asymptotic limit with proper use of decoy states. And with the using of discrete modulation, the proposed CV-MDI-QKD protocol has simpler implementation and outperform previous protocols in terms of achievable maximal transmission distance, which precisely solve the bottleneck of the original Gaussianmodulated CV-MDI-QKD protocol.

Security Analysis of Discrete-Modulated Continuous-Variable Quantum Key Distribution over Seawater Channel

“…Studies have shown that discrete modulation is more suitable for long-distance communication than Gaussian modulation because of the relatively large key generation rate even at a lower SNR [12,31]. Up to now, different types of discretely modulated CV-QKD schemes have been investigated, including the four-state protocol, eight-state protocol, sixteen-state protocol, and so on.…”

Long-distance continuous-variable measurement-device-independent quantum key distribution with postselection

“…Unfortunately, developing a protocol that allows exploitation of the practicality of the CV MDI regime at long distance is a difficult problem in recent QKD theory [36][37][38][39]. A great deal of effort has been directed at improving the performance of this type of protocol, with proposals based on virtual photon subtraction [40,41], unidimensional modulation [42], or discrete modulation [43]. While these protocols offered an improvement in the range of the asymmetric configuration, in which the relay is positioned within close range of one of the parties, their applicability in the symmetric configuration, in which the relay is positioned equidistance between the parties, was very limited.…”

On the Photon Subtraction-Based Measurement-Device-Independent CV-QKD Protocols

“…To overcome these practical security loopholes of CV-QKD protocols various measurement device-independent (MDI) CV-QKD protocols have been advocated [25]- [29]. The MDI QKD concept was first introduced in DV-QKD context to solve for various detector side-channel attacks [30], [31].…”

“…While the employment of MDI concept can solve for detector side-channel attacks and simultaneously extend the transmission distance for DV-QKD, this is not the case for CV-QKD applications. The achievable transmission distances for symmetric MDI-based CV-QKD schemes, wherein Charlie is located in the middle of the link (at equal distances from Alice and Bob), is extremely short [28], [29]. To extend the transmission distance of symmetric MDI CV-QKD, the extreme asymmetric case has been introduced (see for example [28], [29]); however, the transmission distances are still shorter than that of conventional CV-QKD schemes.…”

“…The achievable transmission distances for symmetric MDI-based CV-QKD schemes, wherein Charlie is located in the middle of the link (at equal distances from Alice and Bob), is extremely short [28], [29]. To extend the transmission distance of symmetric MDI CV-QKD, the extreme asymmetric case has been introduced (see for example [28], [29]); however, the transmission distances are still shorter than that of conventional CV-QKD schemes. Another alternative to extend the transmission distance is to employ the virtual photon subtraction (PS) method [32]- [34].…”