Quantum secure dialogue based on single photons and controlled-not operations

A quantum dialogue protocol is proposed and proved to be secure. In our scheme, single photons are used as a quantum channel, the security of our scheme is guaranteed by BB84 QKD and the fact that controlled-not operation ensures the control qubit is unchanged and the target qubit flips only if the control qubit is [image omitted]. By using controlled-not operations, two legitimate communicators can share a private initial state and realize quantum dialogue securely. Compared with previous quantum dialogue protocols, the good merit of this work is that the insecurity, i.e. 'information leakage' is eliminated. Comparing this dialogue protocol with the recent work in another paper [Shi, G.F.; Xi, X.Q.; Hu, M.L.; Yue, R.H. Opt. Commun. 2010, 283, 1984] where two adjacent single photons must be of the same quantum state, this scheme is experimentally simple.