The information leakage is a challenge in the design of Controlled quantum dialogue (CQD) protocols and the CQD protocol over noise channel has not been well researched. A CQD protocol without information leakage over an ideal channel is first proposed, where single photons are used to carrying secret information and pre-shared keys are used to authenticate identity and control information decoding for the prevention of information leakage, moreover, a novel kind of the unitary encoding operations with good property on the quantum operation discrimination are adopted to avoid active attacks from outside eavesdropper. By substituting logical qubits for single photons and constructing unitary encoding operations with the same property based on logical qubits, three fault-tolerant versions of the proposed CQD protocol are obtained, which can combat collective-dephasing, collective-rotation and all kinds of unitary collective noise, respectively. The security and efficiency analysis show the proposed protocols are appropriate for secure quantum dialogue in practice.
The information leakage is a challenge in the design of Controlled quantum dialogue (CQD) protocols and the CQD protocol over noise channel has not been well researched. A CQD protocol without information leakage over an ideal channel is first proposed, where single photons are used to carrying secret information and pre-shared keys are used to authenticate identity and control information decoding for the prevention of information leakage, moreover, a novel kind of the unitary encoding operations with good property on the quantum operation discrimination are adopted to avoid active attacks from outside eavesdropper. By substituting logical qubits for single photons and constructing unitary encoding operations with the same property based on logical qubits, three fault-tolerant versions of the proposed CQD protocol are obtained, which can combat collective-dephasing, collective-rotation and all kinds of unitary collective noise, respectively. The security and efficiency analysis show the proposed protocols are appropriate for secure quantum dialogue in practice.
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,two fault tolerant channel-encrypting quantum dialogue(QD)protocols against collective noise are presented.One is against collective-dephasing noise,while the other is against collective-rotation noise.The decoherent-free states,each of which is composed of two physical qubits,act as traveling states combating collective noise.Einstein-Podolsky-Rosen pairs,which play the role of private quantum key,are securely shared between two participants over a collective-noise channel in advance.Through encryption and decryption with private quantum key,the initial state of each traveling two-photon logical qubit is privately shared between two participants.Due to quantum encryption sharing of the initial state of each traveling logical qubit,the issue of information leakage is overcome.The private quantum key can be repeatedly used after rotation as long as the rotation angle is properly chosen,making quantum resource economized.As a result,their information-theoretical efficiency is nearly up to 66.7%.The proposed QD protocols only need single-photon measurements rather than two-photon joint measurements for quantum measurements.Security analysis shows that an eavesdropper cannot obtain anything useful about secret messages during the dialogue process without being discovered.Furthermore,the proposed QD protocols can be implemented with current techniques in experiment.
Based on the deterministic secure quantum communication, we present a novel quantum dialogue protocol without information leakage over the collective noise channel. The logical qubits and four-qubit decoherence-free states are introduced for resisting against collective-dephasing noise, collective-rotation noise and all kinds of unitary collective noise, respectively. Compared with the existing similar protocols, the analyses on security and information-theoretical efficiency show that the proposed protocol is more secure and efficient.
In this paper, two robust quantum dialogue (QD) protocols against collective-dephasing noise and collective-rotation noise are proposed, respectively, by virtue of logical qubits and controlled-not (CNOT) operations. The party in charge of preparation produces logical qubits as travelling states to combat collective noise. The other party knows the initial prepared states of logical qubits with resort to the CNOT operations, and decodes out the preparation party's secret messages with the help of a classical information string sent from the preparation party. The preparation party reads out the other party's secret messages by virtue of quantum secure direct communication. In this way, the risk of information leakage is effectively avoided. Throughout the proposed protocols, only the single-photon measurements are needed for quantum measurements. Compared with previous antinoise QD protocols, the proposed protocols have the highest information-theoretical efficiency. Compared with the recent QD protocols designed by the author which need to prepare two adjacent logical qubits in the same quantum state, the proposed protocols are more experimentally feasible, as they do not have this special requirement.
Quantum system is inevitably affected by the external environment in the real world. Two controlled quantum dialogue protocols are put forward based on logical χ-type states under collective noise environment. One is against collective-dephasing noise, while the other is against collective-rotation noise. Compared with existing protocols, there exist several outstanding advantages in our proposed protocols: Firstly, the χ-type state is utilized as quantum channels, it possesses better entanglement properties than GHZ state, W state as well as cluster state, which make it difficult to be destroyed by local operations. Secondly, two kinds of logical χ-type states are constructed by us in theory, which can be perfectly immune to the effects of collective noise. Thirdly, the controller can be offline after quantum distribution and permission announcement, without waiting for all the participants to complete the information coding. Fourthly, the security analysis illuminates that our protocols can not only be free from the information leakage, but also resist against the intercept-and-resend attack, the entanglement-and-measure attack, the modification attack, the conspiring attack, and especially the dishonest controller’s attacks.
At present, the anti-noise property and the information leakage resistant property are two great concerns for quantum dialogue(QD). In this paper, two anti-noise QD protocols without information leakage are presented by using the entanglement swapping technology for two logical Bell states. One works well over a collective-dephasing noise channel, while the other takes effect over a collective-rotation noise channel. The negative influence of noise is erased by using logical Bell states as the traveling quantum states. The problem of information leakage is avoided by swapping entanglement between two logical Bell states. In addition, only Bell state measurements are used for decoding, rather than four-qubit joint measurements.