A theoretical protocol of quantum dialogue is proposed, which uses a class of three-photon W states as quantum channel. After two-step security check, four-bit secret message can be transmitted to each other by transmitting of single photon with the aid of two-bit classical information.
A protocol for quantum dialogue is proposed to exchange directly the communicator's secret messages by using a three-dimensional Bell state and a two-dimensional Bell state as quantum channel with quantum superdence coding, local collective unitary operations, and entanglement swapping. In this protocol, during the process of transmission of particles, the transmitted particles do not carry any secret messages and are transmitted only one time. The protocol has higher source capacity than protocols using symmetric two-dimensional states. The security is ensured by the unitary operations randomly performed on all checking groups before the particle sequence is transmitted and the application of entanglement swapping.
Cluster state quantum dialogue is proposed,which enables both legitimate parties to exchange their 4 bit secret messages in a direct way.Compared with the there-particle W states,the shemes have following advantages.After two-step security check,four-bit secret message can be transmitted to each other by transmitting of single particle with the aid of two-bit classical information.The scheme can discard the drawback of the intercept-resend attack,the entangle-measure attack,and the optimal incoherent attack.
In this paper, a quantum dialogue (QD) protocol without information leakage is proposed at first by using single photons as the quantum resource, where each single photon is directly encoded for transmitting secret messages. Two communication parties share the quantum state generation rule in advance. The preparation party reads out the other party's secret messages by virtue of quantum secure direct communication. The other party decodes out the preparation party's secret messages with the aid of a classical information sequence indicating the preparation bases of single photons sent from the preparation party. In this way, the information leakage problem is avoided. The proposed protocol with single photons only needs the single-photon measurements. Different from Shi's two recent QD protocols based on single photons, the proposed protocol with single photons needs neither to prepare two adjacent single photons in the same quantum state nor to perform the controlled-not (CNOT) operations. Finally, the proposed protocol with single photons is generalized into the cases of resisting collective-dephasing noise and collective-rotation noise by using logical qubits as the quantum resource, respectively.
In this paper, we point out Partially Entangled States quantum dialogue, which enables both legitimate parties to exchange their 2 bit secret messages in a direct way. Two step security check guarantees the security of this protocol. Partially Entangled States used as information carrier are easy to prepare and store, there is no need to transmit quantum states with secret message in quantum channel and two users can simultaneously communicate with the third party. The protocol is secure against the intercept-resend attack and the entangle-measure attack.
In this paper, we point out Partially Entangled States quantum dialogue, which enables both legitimate parties to exchange their 2 bit secret messages in a direct way. Two step security check guarantees the security of this protocol. Partially Entangled States used as information carrier are easy to prepare and store, there is no need to transmit quantum states with secret message in quantum channel and two users can simultaneously communicate with the third party. The protocol is secure against the intercept-resend attack and the entangle-measure attack.