Fault-Tolerant Controlled Quantum Dialogue Using Logical Qubit

The information leakage is a challenge in the design of Controlled quantum dialogue (CQD) protocols and the CQD protocol over noise channel has not been well researched. A CQD protocol without information leakage over an ideal channel is first proposed, where single photons are used to carrying secret information and pre-shared keys are used to authenticate identity and control information decoding for the prevention of information leakage, moreover, a novel kind of the unitary encoding operations with good property on the quantum operation discrimination are adopted to avoid active attacks from outside eavesdropper. By substituting logical qubits for single photons and constructing unitary encoding operations with the same property based on logical qubits, three fault-tolerant versions of the proposed CQD protocol are obtained, which can combat collective-dephasing, collective-rotation and all kinds of unitary collective noise, respectively. The security and efficiency analysis show the proposed protocols are appropriate for secure quantum dialogue in practice.