Symmetric Quantum Secure Direct Communication Protocols Immune to Collective Noises

Quantum secure direct communication (QSDC) enables the direct and secure transmission of messages without the need for prior key distribution, offering a groundbreaking paradigm in quantum communication. This paper presents a novel symmetric QSDC protocol that ensures immunity to collective-phase and collective-rotation noises while enabling efficient and two-way message transfer. The proposed protocol features an innovative approach where qubits are transmitted only during the initial entanglement sharing phase, eliminating the need to send message carrying qubits thereafter. By leveraging this design, the protocol minimizes vulnerability to external noise and eavesdropping attempts. The symmetry of the protocol allows both parties to exchange messages seamlessly and securely, ensuring equal communication procedure. Analytical analysis and theoretical proofs demonstrate the robustness and security of the protocol under non-secure quantum channel, marking a significant advancement in practical quantum communication systems. The proposed scheme follows an entanglement-based QSDC paradigm, where confidential information is embedded into quantum correlations rather than being directly transmitted over the quantum channel.