Improvement of self-referenced continuous-variable quantum key distribution with quantum photon catalysis.

Quantum photon-catalysis operations can be utilized for improving the performance of continuous-variable quantum key distribution (CVQKD) systems. Motivated by characteristics of quantum photon-catalysis operations that can be implemented by the existing technologies, we consider the performance improvement of self-referenced (SR) CVQKD involving zero-photon catalysis operation. We find that the zero-photon catalysis can be regarded as a noiseless attenuation, and the numerical simulations show that the zero-photon catalysis (ZPC)-based SR-CVQKD scheme outperforms the original SR-CVQKD scheme. In addition, to highlight the advantage of applying zero-photon catalysis operation into SR-CVQKD systems, we make a comparison about the performances between the ZPC-based SR-CVQKD scheme and the previous single-photon subtraction (SPS)-based SR-CVQKD scheme. Numerical simulations show that the ZPC-based SR-CVQKD is superior to the single-photon subtraction case with respect to the transmission distance and the tolerable excess noise. Especially, the ZPC-based SR-CVQKD allows the lower quantum detection efficiency and the higher electronic noise to achieve the same performance. These results show that the proposed protocol is expected to provide theoretical reference for the practical application of SR-CVQKD in metropolitan areas.