On the Deterministic Secure Quantum Communication using Four-particle Entangled State and Entanglement Swapping

Recently, Xiu et al. proposed a deterministic secure quantum com-munication (DSQC) protocol using the entanglement swapping of four-particle genuine entangled states. Later, Qin et al. showed a double-CNOT attack on the protocol and also provided an improvement to avoid the attack. This work tries to use a batch of decoy single photons prepared randomly in one of four different states, to enhance the qubit efficiency on their DSQC protocols and avoid the double-CNOT attack at the same time