Performance improvement of plug-and-play dual-phase-modulated continuous-variable quantum key distribution with quantum catalysis

Continuous-variable quantum key distribution based on plug-and-play dual-phase-modulated coherent-states (DPMCS) protocol has been proved to be equivalent to the one-way Gaussian-modulated coherent-states protocol, but it is not just limited to this. This protocol can effectively against the LO-aimed attacks and maintain the system robust. However, the maximum transmission distance of the protocol is restricted due to its large excess noise. In this paper, we enhance the plug-and-play DPMCS protocol using quantum catalysis operation, which can be implemented by the existing technologies. To further highlight the advantage of the implementation of quantum catalysis operation, we make performance comparison not only between the proposed protocol and the original scheme but also the single-photon subtraction-based (SPS) plug-and-play DPMCS protocol. Security analysis shows that the proposed protocol can extend the maximum transmission distance up to hundreds of kilometers even under the effect of the imperfect source noise and show more excellent performance than the SPS-based plug-and-play DPMCS protocol. Furthermore, we also take the finite-size effect into consideration and thus achieve more practical results than those obtained in the asymptotic limit.