Simple protocol for secure decoy-state quantum key distribution with a loosely controlled source
Xiang‐Bin Wang, Cheng-Zhi Peng, Jian-Wei Pan · Applied Physics Letters · 2007
The method of decoy-state quantum key distribution requests different intensities of light pulses. Existing theory has assumed exact control of intensities. Here the authors propose a simple protocol which is secure and efficient even there are errors in intensity control. In their protocol, decoy pulses and signal pulses are generated from the same father pulses with a two-value attenuation. Given the upper bound of fluctuation of the father pulses, their protocol is secure provided that the two-value attenuation is done exactly. They propose to use unbalanced beam splitters for a stable attenuation.