Security analysis of linear optics cloning machine-enhanced passive state preparation continuous-variable quantum key distribution

In this paper, the security of linear optics cloning machine-enhanced passive state preparation continuous-variable quantum key distribution is investigated. The employment of passive state preparation eliminates the strict requirements on electro-optical modulators, while an appropriately tuned linear optics cloning machine can compensate the preparation noise introduced in passive state preparation and improve the system performance. The expression of the composable secret key rate in the finite-size regime of the proposed scheme is obtained. Simulation results demonstrate that the proposed scheme can effectively enhance the secret key rate and increase the maximum secure transmission distance.