Optimal decoy intensity for decoy quantum key distribution
Masahito Hayashi · Journal of Physics A Mathematical and Theoretical · 2016
In the decoy quantum key distribution, we show that a smaller decoy intensity gives a better key generation rate in the asymptotic setting when we employ only one decoy intensity and the vacuum pulse. In particular, the counting rate of single photon can be perfectly estimated in the limit that the decoy intensity is infinitesimally small. The same property holds even when the intensities cannot be perfectly identified. Further, we propose a protocol to improve the key generation rate over the existing protocol under the same decoy intensity.