Security enhancement of amplitude-shift keying-type asymmetric quantum communication systems

Recently, we proposed an amplitude-shift keying asymmetric quantum communication system and evaluated its reliability when using the quasi-Bell state and two-mode squeezed vacuum state (TSVS) as an entangled light source. In this paper, we evaluate the security of the system and find that either security or reliability can be enhanced depending on the entangled light sources. We also consider an approach to enhance the security of the system as well as its reliability by increasing the number of signal modes. Interestingly, we find that the quasi-Bell state always performs better than the TSVS under certain conditions.