It is shown that the entangled states of a two- or multi-component system form a representation of the SU(2) phase states. The use of the dualism of base and entangled states is proposed for the quantum information transmission secured from eavesdropping.
Semi-quantum communication, serving as transitional technology between quantum communication and classical communication, bridges fully quantum-capable users with “classical” users who have limited quantum capabilities. It provides practical solution for application scenarios that struggle to bear high costs of quantum resources. This paper designs a novel deterministic secure semi-quantum communication protocol that significantly enhances communication efficiency by utilizing Greenberger-Horne-Zeilinger (GHZ) states for entanglement compression. The protocol consists of two core components: eavesdropping detection mechanism and transmission process for compressed and encrypted information sequences. During the eavesdropping detection phase, the protocol incorporates decoy photon technology to effectively expose and prevent potential eavesdropping attempts. In the secret information transmission phase, the protocol combines the advantages of a pseudo-random number generator driven by one-way hash function and GHZ-state-based entanglement compression technology to randomly rearrange and compress-encrypt the secret information, ensuring its high security and integrity during transmission. Ultimately, the receiver can accurately decrypt and restore the original secret information using a pre-agreed key. The protocol not only successfully integrates multiple advanced technologies to resist various attacks and ensure the absolute secure transmission of secret information, but also provides strong support for practical applications with its communication efficiency of up to 50% and high practicality.
We propose an artificial-noise (AN)-aided transmission scheme to achieve two objectives: 1) energize a single-antenna legitimate transmitter (Alice) by receiving an AN signal from a multi-antenna base-station (Bob) and 2) secure the information signal transmitted from Alice to Bob from eavesdropping by a multi-antenna eavesdropper (Eve). We assume a two-phase transmission scheme. In the first phase, Bob transmits two orthogonal precoded AN vectors to power Alice and confuse Eve. In the second phase, Alice transmits her information signal to Bob along with an amplified version of the AN signal to confuse Eve. Our numerical results show that the proposed scheme can efficiently power Alice while securing her transmissions. Moreover, we show that the achieved average secrecy rate under the proposed scheme outperforms the case when the conventional communication scheme is employed.