Improved Passive State Preparation–Continuous Variable Quantum Key Distribution Scheme Based on Non-Gaussian Operations

Passive state preparation–continuous variable quantum key distribution (PSP-CVQKD) protocol inherits the advantage of high secret key rate (SKR) of CVQKD, while overcoming the drawback of complex modulation equipment in GMCS-CVQKD. In recent years, it has received extensive attention in the experimental field. Even so, short transmission distance remains its prominent issue. In this paper, a scheme for introducing non-Gaussian operations into PSP-CVQKD in optical fiber links is proposed. We derive the input–output relationship of the system, as well as the calculation formulas for the success probability and SKR, when non-Gaussian operations are introduced at both sides of the channels respectively. The results indicate that the improved PSP-CVQKD scheme is feasible in enhancing the SKR performance and can effectively increase the transmission distance. Our scheme provides beneficial ideas for further in-depth research on non-Gaussian operations and the performance improvement of other PSP-CVQKD protocols.