Fault-Tolerant Semi-quantum Secure Direct Communication Scheme in Noisy Environment

We present an anti-noise quantum states, which is |φ1> = \( \frac{ 1}{\sqrt 2} \)(|0L0L> + |1L1L>) or |Ψ2> = \( \frac{ 1}{\sqrt 2} \)(|0L1L> + |1L0L>) to resist collective dephasing noise and |φ3> = \( \frac{ 1}{\sqrt 2} \)(|0R0R> + |1R1R>) or |Ψ4> = \( \frac{ 1}{\sqrt 2} \)(|0R1R> + |1R0R>) to resist collective rotation noise. With the anti-noise quantum states, Alice encode her information. She keep the first qubit and send the second qubit to Bob. Bob can choose to measure which means measure the second qubit by the basis {|0L>, |1L>} or {|0R>, |1R>}, or can choose to reflect which means send the qubit with undisturbed. About the transmission efficiency, when Alice transfers the information of 2n bits, Bob can get the information of n bits. Moreover, the security analysis of our scheme is also given.