2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/91960In this letter we propose a theoretical deterministic secure direct bidirectional quantum communication protocol by using swapping quantum entanglement and local unitary operations, in which the quantum channel for photon transmission can be discarded, hence any attack with or without eavesdropping or even the destructive attack without scruple is impossible.Submitted to PRL. Comments and helps are welcomeQuantum Physicstext