Trojan horse attack free fault-tolerant quantum key distribution protocols

Abstract

This work proposes two quantum key distribution (QKD) protocols--each of which is robust under one kind of collective noises--collective-dephasing noise and collective-rotation noise. Due to the use of a new coding function which produces error-robust codewords allowing one-time transmission of quanta, the proposed QKD schemes are fault-tolerant and congenitally free from Trojan horse attacks without having to use any extra hardware. Moreover, by adopting two Bell state measurements instead of a 4-GHZ state joint measurement for decoding, the proposed protocols are practical in combating collective noises.