QUANTUM SECURE DIRECT COMMUNICATION WITHOUT USING PERFECT QUANTUM CHANNEL
Jian Wang, Quan Zhang, Chaojing Tang
Abstract
Most of quantum secure direct communication protocols need a pre-established secure quantum channel. Only after insuring the security of quantum channel, could the sender encode the secret message and send them to the receiver through the secure channel. In this paper, we present a quantum secure direct communication protocol using Einstein-Podolsky-Rosen pairs without insuring the security of quantum channel before transmitting the secret message. Compared with the protocol proposed by Deng et al. [Phys. Rev. A 68, 042317 (2003)] and the scheme proposed by Yan et al. [Euro. Phys. J. B 41, 75 (2004)], the present protocol provides higher efficiency.