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.
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.
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 robust quantum dialogue (QD) protocols over collective-dephasing noise channel and collective- rotation noise channel are proposed, respectively, by using three-qubit entangled states as the initial quantum resource. Alice generates a series of three-qubit entangled states and divides them into a physical qubit sequence and a logical qubit sequence. Then, Alice sends the logical qubit sequence to Bob. Afterward, Alice and Bob measure the physical qubit sequence and the logical qubit sequence, respectively. According to his measurement result, Bob generates a new logical qubit sequence with no measurement performed. Then, Bob encodes his secret messages on the new logical qubit sequence by performing logical unitary operations on it. Afterward, Bob sends the encoded logical qubit sequence back to Alice. Finally, Alice encodes her secret messages on the encoded logical qubit sequence from Bob by performing logical unitary operations on it and publishes her measurement. As a result, Alice and Bob can decode out each other's secret messages. By virtue of the measurement correlation of three-qubit entangled states, two participants share the initial states of message logical qubits privately. In this way, the information leakage problem is overcome. The proposed protocols only need the single-photon measurements. Compared with previous QD protocols workable over collective noise channels, the proposed protocols have the highest information-theoretical efficiency.
In this paper, two robust quantum dialogue (QD) protocols against collective-dephasing noise and collective-rotation noise are presented, respectively. In each of the proposed QD protocols, four logical Bell states, each of which is made up of four physical qubits, are used to combat collective noise. The information leakage problem is overcome by directly transmitting the auxiliary logical Bell states in two steps from one communication party to the other. For decoding, Bell state measurements rather than four-qubit joint measurements are used. The effectiveness against an eavesdropper's active attacks such as the intercept-resend attack, the measure-resend attack, the entangle-measure attack and the Trojan horse attack can be guaranteed.
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.
Quantum dialogue allows both communication parties to execute secure direct communication simultaneously and bidirectionally. In recent years, due to the possible applications of quantum communication technologies in military, finance, medicine and other fields, quantum dialogue has been widely concerned. In the year of 2017, NR Zhou et al designed a new quantum dialogue protocol by using the continuous-variable two-mode squeezed vacuum states, where the two communication parties encode their own secret information into the entangled optical modes with the translation operations and each communication party could deduce the secret information of their counterparts with the help of his or her secret information and the Bellbasis measurement results [1]. LH Gong et al devised an efficient three-party quantum dialogue protocol based on the continuous variable GHZ entangled states [2]. NR Zhou et al proposed a secure quantum dialogue protocol based on single-photons, which not only overcomes information leakage but also possesses an acceptable efficiency. M Xiao et al presented a novel quantum dialogue protocol without information leakage over the collective noise channel, where the logical qubits and four-qubit decoherence-free states were introduced to resist against collective-dephasing noise, collective-rotation noise and all kinds of unitary collective noise [4]. T Hwang et al proposed an authenticated quantum dialogue based on Bell states, allowing two communicators to perform mutual authentication and secure bidirectional communications simultaneously via public classical channels [5]. TY Ye proposed a quantum dialogue scheme by employing logical Bell states as the quantum resource to combat the collective-dephasing noise and the collective-rotation noise, which can accomplish the mutual identification and the dialogue between two participants simultaneously and securely over one kind of collective noise channels [6]. M Wang et al proposed a quantum dialogue protocol based on four-qubit entangled state, which is constructed by an EPR pair and two different single qubits through three Controlled-Not gates [7]. By using Bell measurements and the corresponding unitary operations, two users can exchange their messages simultaneously and directly without sharing any secret keys beforehand. The above protocols exploited different quantum states and involved two or three communication parties basically. These protocols cannot satisfy the practical applications of quantum dialogue in future possible quantum communication networks. Therefore, we will propose a multiparty continuous variable quantum dialogue protocol. Multiparty quantum dialogue protocol enables multiple communication parties to transmit and/or receive information at the same time. The protocol could ensure that there is no information leakage in the communication process according to the uncertainty principle and quantum non-cloning theorem.
By designing two-step transmissions, this paper presents two quantum dialogue (QD) protocols that can resist different types of collective noise in the quantum channel. The message carrier of the proposed scheme utilizes decoherence-free subspaces to remain invariant under the impact of collective noise. We employ combinations of these quantum states to form decoy photon pairs, ensuring secure transmission and preventing message distortion. Based on the principle that a single photon in an EPR pair reveals no information about its actual state, an EPR pair requires only one photon for protection during transmission. This property effectively reduces the number of decoy photons needed to ensure the security of quantum transmission, which can also be applied to the logical EPR pair consisting of logical qubits. A quantum logic circuit is also designed to demonstrate the practical implementation of shuffling the logical qubits within each logical EPR pair. Therefore, the proposed two-step QD protocols require only half as many decoy photons to achieve the same security level as other state-of-the-art QD schemes. The significant reduction in the utilization of decoy photons improves the qubit efficiency of the proposed QD protocols compared to other existing works in the field. Additionally, the security analysis of the proposed QD schemes ensures the absence of information leakage and resistance to common quantum attacks.