Cryptanalysis and improvement of the robust quantum dialogue protocols based on the entanglement swapping between any two logical Bell states and the shared auxiliary logical Bell state

Abstract

As we know, it does not allow that a secure quantum communication protocol has the information leakage problem. Unfortunately, we find that there is the information leakage problem in the two quantum dialogue (QD) protocols which are respectively based on entanglement swapping between two logical Bell states under the collective-dephasing noise and the collective-rotation noise. To mend this loophole, they are masterly improved. It is proven that the improved QD protocols are without information leakage problem. Incidentally, they have some other obvious advantages compared to the previous ones.