Efficient Quantum Secure Direct Communication Research Articles

Efficient quantum secure direct communication scheme based on single photons

In this work, we first introduce the specific steps of a quantum-secure direct communication scheme that sends a single photon at a time. Based on the basic steps of the scheme, it is gradually extended to a quantum secure direct communication scheme that transmits single-photon sequences twice and four times, with emphasis on the coding rules corresponding to each scheme. The purpose is that through the above scheme, it can be intuitively seen in the subsequent efficiency analysis that with the increase of the number of transmissions, the classification of single photons can be increased, and the encoding capacity of each single photon and the transmission efficiency of quantum states in the entire communication can be greatly improved. Finally, a universal scheme and coding rules for quantum secure direct communication by sending single photons in an integer power of 2 are proposed, and after security analysis the scheme proves to be safe and feasible. Through the efficiency analysis, the communication efficiency of this scheme is higher than that of the existing scheme, and the implementation of this scheme only uses a single photon, does not involve with quantum entanglement, and this scheme has more application values.

Efficient quantum secure direct communication with complete Bell‐state measurement

Quantum secure direct communication (QSDC) is a powerful technique of transmitting confidential information directly and securely based on the pre-established secure quantum channel and block transmission. Here we propose an efficient QSDC protocol using the complete Bell-state measurement (CBSM) resorting to linear optical elements and temporal-polarization hyperentanglement. In this protocol, the polarized entangled photons are utilized as the information carrier, and all the detection events of CBSM can be identified with common single-photon detectors instead of photon number resolving detectors due to the introduction of temporal degree of freedom (DOF). Moreover, since all the two-photon detection events in CBSM are effective and can be preserved with the efficiency of 100% rather than 50% in the previous QSDC, the quantum efficiency of QSDC can be doubled by encoding more messages on entangled photon pairs.

Efficient Quantum Secure Direct Communication Protocol Based on Quantum Channel Compression

The article presents the concept of quantum channel compression—decrease in the amount of qubits utilized in a protocol—which is achieved by means of data source encoding. It is also a report on an efficient quantum secure direct communication (QSDC) protocol, which is used for transferring predetermined cryptographic keys (e.g., keys that are generated by the algorithm of Advanced Encryption Standard). This type of quantum secure communication combines the ideas of dense coding process and quantum channel compression. It is justified that such a protocol obtains overall transfer efficiency over unity, i.e., over 100%.

The analysis of high-capacity quantum secure direct communication using polarization and orbital angular momentum of photons

Higher channel capacity and noise elimination are the key requirements for the implementation of long-distance quantum communication. As the additional degrees of freedom (DoF) of photons can be employed to achieve higher channel capacity and security beyond the polarizations DoF of photons, the photonic qubits are always employed as the flying qubits in quantum communication and quantum information processing. Here, exploiting the multiple DoFs of photons, we present an efficient quantum secure direct communication protocol based on the coding and manipulation of qubits on both the polarization and the orbital angular momentum of photons. Also, the numerical simulation is studied to further clarify the improvement of the channel capacity and the security. It is found that the channel capacity and the error rate (caused by eavesdropping) of the QSDC protocol which encoded on the polarization DoF and the OAM DoF is significantly higher than that of coding on only polarization DoF. We believe this work could provide more evidence for the applications of higher-dimensional qubits in quantum information science.

Quantum secure direct communication over the collective amplitude damping channel

An efficient quantum secure direct communication protocol is presented over the amplitude damping channel. The protocol encodes logical bits in two-qubit noiseless states, and so it can function over a quantum channel subjected to collective amplitude damping. The feature of this protocol is that the sender encodes the secret directly on the quantum states, the receiver decodes the secret by performing determinate measurements, and there is no basis mismatch. The transmission’s safety is ensured by the nonorthogonality of the noiseless states traveling forward and backward on the quantum channel. Moreover, we construct the efficient quantum circuits to implement channel encoding and information encoding by means of primitive operations in quantum computation.

Efficient Quantum Secure Direct Communication with Authentication

Two protocols of quantum direct communication with authentication [Phys. Rev. A 73 (2006) 042305] were recently indicated to be insecure against the authenticator Trent attacks [Phys. Rev. A 75 (2007) 026301]. We present two efficient protocols by using four Pauli operations, which are secure against inner Trent attacks as well as outer Eve attacks. Finally we generalize them to multiparty quantum direction communication.

An efficient quantum secure direct communication scheme with authentication

In this paper an efficient quantum secure direct communication (QSDC) scheme with authentication is presented, which is based on quantum entanglement and polarized single photons. The present protocol uses Einstein–Podolsky–Rosen (EPR) pairs and polarized single photons in batches. A particle of the EPR pairs is retained in the sender's station, and the other is transmitted forth and back between the sender and the receiver, similar to the ``ping–pong'' QSDC protocol. According to the shared information beforehand, these two kinds of quantum states are mixed and then transmitted via a quantum channel. The EPR pairs are used to transmit secret messages and the polarized single photons used for authentication and eavesdropping check. Consequently, because of the dual contributions of the polarized single photons, no classical information is needed. The intrinsic efficiency and total efficiency are both 1 in this scheme as almost all of the instances are useful and each EPR pair can be used to carry two bits of information.

Efficient One-Sender Versus N-Receiver Quantum SecureDirect Communication

An efficient quantum secure direct communication protocol withone-sender versus N-receiver is proposed. The secret bits can beencoded in the N+1-particle GHZ states and can be decoded by the Nreceivers with a classical information of the sender plus their ownmeasurement outcomes. Any attacks can be detected by comparingmeasurement results on the detecting states.

Quantum Secure Direct Communication Network with Two-StepProtocol

An efficient quantum secure direct communication network protocol with thetwo-step scheme is proposed by using the Einstein–Podolsky–Rosen (EPR)pair block as the quantum information carrier. The server, say Alice,prepares and measures the EPR pairs in the quantum communication and theusers perform the four local unitary operations to encode their message.Anyone of the legitimate users can communicate another one on thenetwork securely. Since almost all of the instances in this scheme areuseful and each EPR pair can carry two bits of information, theefficiency for qubits and the source capacity both approach the maximalvalues.