Journal of Xidian University
Application of quantum LDPC codes to quantum key distribution
Wang Xiao
Abstract
In this paper,the security of BB84 key distribution protocol is considered.We assume that in the protocol the eavesdropper Eve intercepts/resends photons transmitted between Alice and Bob with probability e.First,the BB84 key distribution protocol will be made equivalent to a special Wire-tap channel model,where the main channel is a binary symmetric channel with probability of flipping bits 0.25e and the eavesdropper's channel is a binary erasure channel with probability of erasure 1-e.Using the coding method and properties of quantum LDPC codes CSS(C1,C2) for secure communication across the Wire-tap channel in the BB84 protocol is an equivalent proof of the security of BB84 protocol.Finally,the tolerable error rate of the BB84 protocol based on quantum LDPC codes can be obtained by calculating the secrecy capacity of this special Wire-tap channel.