Secure Key Rate of the BB84 Protocol using Finite Sample Bits

摘要

We improve the nonasymptotic key rate shown by Scarani and Renner by proposing several methods to construct tighter conservative confidence interval of the phase error rate than one shown by them. In addition, we show that the accurate channel estimation method nonasymptotically increases the key rate over the amplitude damping channel as well as the asymptotic case in the BB84 protocol.