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, 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 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.
This paper puts forward a novel quantum dialogue (QD) protocol without information leakage based on single photons in both polarization and spatial-mode degrees of freedom. In this protocol, the receiver sends his private message to the sender in the way of quantum secure direct communication; and the receiver decodes out the private message of the sender with the help of auxiliary single photons in two degrees of freedom, double controlled-not (CNOT) operations and an auxiliary classical bit sequence sent from the sender. As a result, no information leakage takes place. Moreover, this protocol is proven to defeat the intercept-resend attack, the measure-resend attack, the entangle-measure attack and the Trojan horse attack from an outside eavesdropper. This protocol only employs single photons in two degrees of freedom as quantum resource and needs single-photon measurements. The qubit efficiency of this protocol is as high as 66.7%.
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.
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.
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.
A quantum dialogue protocol is proposed and proved to be secure. In our scheme, single photons are used as a quantum channel, the security of our scheme is guaranteed by BB84 QKD and the fact that controlled-not operation ensures the control qubit is unchanged and the target qubit flips only if the control qubit is . By using controlled-not operations, two legitimate communicators can share a private initial state and realize quantum dialogue securely. Compared with previous quantum dialogue protocols, the good merit of this work is that the insecurity, i.e. ‘information leakage’ is eliminated. Comparing this dialogue protocol with the recent work in another paper [Shi, G.F.; Xi, X.Q.; Hu, M.L.; Yue, R.H. Opt. Commun. 2010, 283, 1984] where two adjacent single photons must be of the same quantum state, this scheme is experimentally simple.