Robust Quantum Secure Direct Communication and Deterministic Secure Quantum Communication over Collective Dephasing Noisy Channel

We propose two schemes for quantum secure direct communication （QSDC） and deterministic secure quantum communication （DSQC） over collective dephasing noisy channel. In our schemes, four special two-qubit states are used as the quantum channel. Since these states are unchanged through the collective dephasing noisy channel, the effect of the channel noise can be perfectly overcome. Simultaneously, the security against some usual attacks can be ensured by utilizing the various checking procedures. Furthermore, these two schemes are feasible with present-day technique.