Source monitoring for continuous-variable quantum key distribution
Jian Cheng Yang, Bingjie Xu, Hong Mei Guo · Physical Review A · 2012
The noise in optical source preparation needs to be characterized for the security of practical continuous-variable quantum key distribution (CVQKD). Two feasible schemes, based on either an active optical switch or a passive beamsplitter, are proposed to monitor the variance of the source noise. We derive the security bounds for both schemes against collective attacks in the asymptotical limit and find that the passive scheme performs better. The finite-size effect is also discussed briefly for both schemes.