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

To potentially overcome the practical security loopholes of CV-QKD protocols, in this paper, we propose to use the optimized eight-state measurement-device-independent (MDI) protocol and demonstrate that it can significantly outperform corresponding Gaussian modulation-based MDI and virtual photon subtraction-based MDI CV-QKD protocols in terms of both secret-key rate and achievable transmission distance. Contrary to the common belief that virtual photon subtraction method can extend the distance of MDI CV-QKD protocols, we show that this is not true for fully optimized MDI CV-QKD protocols and realistic system parameters.