Quantum broadcast communication with authentication

Two simple quantum broadcast communication schemes are proposed.A central party can broadcast his secret message to all the legitimate receivers simultaneously.Compared with the three schemes proposed recently (Wang et al.2007 Chin.Phys.16 1868),the proposed schemes have the advantages of consuming fewer quantum and classical resources,lessening the difficulty and intensity of necessary operations,and having higher efficiency.     

量子直接通信

量子直接通信是量子通信中的一个重要分支, 它是一种不需要事先建立密钥而直接传输机密信息的新型通信模式. 本综述将介绍量子直接通信的基本原理, 回顾量子直接通信的发展历程, 从最早的高效量子直接通信协议、两步量子直接通信模型、量子一次一密直接通信模型等, 到抗噪声的量子直接通信模型以及基于单光子多自由度量子态及超纠缠态的量子直接通信模型, 最后介绍量子直接通信的研究现状并展望其发展未来.     

Multiparty Quantum Secret Sharing of Secure Direct Communication Using Teleportation

We present an (n,n) threshold quantum secret sharing scheme of secure direct communication using Greenberger-Horne-Zeilinger state and teleportation.After ensuring the security of the quantum channel,the sender encodes the secret message directly on a sequence of particle states and transmits it to the receivers by teleportation.The receivers can recover the secret message by combining their measurement results with the sender's result.If a perfect quantum channel is used,our scheme is completely secure because the transmitting particle sequence does not carry the secret message.We also show our scheme is secure for noise quantum channel.     

Quantum secure direct communication with Greenberger-Horne-Zeilinger-type state （GHZ state） over noisy channels

We propose a quantum error-rejection scheme for direct communication with three-qubit quantum codes based on the direct communication of secret messages without any secret key shared in advance. Given the symmetric and independent errors of the transmitted qubits, our scheme can tolerate a bit of error rate up to 33.1%, thus the protocol is deterministically secure against any eavesdropping attack even in a noisy channel.     

Quantum secure direct communication with quantum encryption based on pure entangled states

This paper presents a scheme for quantum secure direct communication with quantum encryption. The two authorized users use repeatedly a sequence of the pure entangled pairs (quantum key) shared for encrypting and decrypting the secret message carried by the travelling photons directly. For checking eavesdropping, the two parties perform the single-photon measurements on some decoy particles before each round. This scheme has the advantage that the pure entangled quantum signal source is feasible at present and any eavesdropper cannot steal the message.     

Quantum Secure Direct Communication with Four-Particle Genuine Entangled State and Dense Coding

A quantum secure direct communication scheme using dense coding is proposed. At first, the sender (Alice) prepares four-particle genuine entangled states and shares them with the receiver (Bob) by sending two particles in each entangled state to him. Secondly, Alice encodes secret information by performing the unitarytransformations on her particles and transmits them to Bob. Finally, Bob performs the joint measurements on his particles to decode the secret information. The two-step security test guarantees the security of communication.     

Two-step quantum secure direct communication scheme with frequency coding

Quantum secure direct communication(QSDC) is an important branch of quantum cryptography. It can transmit secret information directly without establishing a key first, unlike quantum key distribution which requires this precursory event. Here we propose a QSDC scheme by applying the frequency coding technique to the two-step QSDC protocol, which enables the two-step QSDC protocol to work in a noisy environment. We have numerically simulated the performance of the protocol in a noisy channel, and the results show that the scheme is indeed robust against channel noise and loss. We also give an estimate of the channel noise upper bound.     

基于三粒子GHZ态的双向量子可控隐形传态

提出基于三粒子GHZ态的双向量子可控隐形传态方案.方案中,使用两个三粒子GHZ态作为量子通道.而根据在量子通道中发送者,接收者和控制者所拥有的粒子的不同以及所采用的测量基的不同,设计出了三方参与的双向可控量子隐形传态方案和四方参与的双向可控量子隐形传态方案.在方案中,Alice和Bob对所拥有的粒子做合适的投影测量,并将其测量结果通知对方和控制者.若控制者同意此次传态,则会对自己所拥有的粒子做投影测量,并将结果告知接收者.接收者根据发送者和控制者的测量信息,做出相对应的幺正操作来重建发送者的量子态.同时三方参与和四方参与的量子可控隐形传态方案提高了通信的安全性.     

控制的量子隐形传态和控制的量子安全直接通信

我们提出了一个控制的量子隐形传态方案。在这方案中，发送方Alice 在监督者Charlie的控制下以他们分享的三粒子纠缠态作为量子通道将二能级粒子未知态的量子信息忠实的传给了遥远的接受方Bob。我们还提出了借助此传态的控制的量子安全直接通信方案。在保证量子通道安全的情况下， Alice直接将秘密信息编码在粒子态序列上，并在Charlie控制下用此传态方法传给Bob。Bob可通过测量他的量子位读出编码信息。由于没有带秘密信息的量子位在Alice 和Bob之间传送，只要量子通道安全， 这种通信不会泄露给窃听者任何信息， 是绝对安全的。这个方案的的特征是双方通信需得到第三方的许可。     

基于量子隐形传态的量子保密通信方案

量子保密通信包括量子密钥分发、量子安全直接通信和量子秘密共享等主要形式.在量子密钥分发和秘密共享中,传输的是随机数而不是信息,要再经过一次经典通信才能完成信息的传输.在量子信道直接传输信息的量子通信形式是量子安全直接通信.基于量子隐形传态的量子通信(简称量子隐形传态通信)是否属于量子安全直接通信尚需解释.构造了一个量子隐形传态通信方案,给出了具体的操作步骤.与一般的量子隐形传态不同,量子隐形传态通信所传输的量子态是计算基矢态,大大简化了贝尔基测量和单粒子操作.分析结果表明,量子隐形传态通信等价于包含了全用型量子密钥分发和经典通信的复合过程,不是量子安全直接通信,其传输受到中间介质和距离的影响,所以不比量子密钥分发更有优势.将该方案与量子密钥分发、量子安全直接通信和经典一次性便笺密码方案进行对比,通过几个通信参数的比较给出各个方案的特点,还特别讨论了各方案在空间量子通信方面的特点.     

Quantum Secure Direct Communication with Authentication Expansion UsingSingle Photons

In this paper we propose two quantum secure direct communication (QSDC) protocols with authentication. The authentication key expansion method is introduced to improve the life of the keys with security. In the first scheme, the third party, called Trent is introduced to authenticate the users that participate in the communication. He sends the polarized photons in blocks toauthenticate communication parties Alice and Bob using the authentication keys. In the communication process, polarized single photons are used to serve as the carriers, which transmit the secret messages directly. The second QSDC process with authentication between two parties is also discussed.     

Network-topology-adaptive quantum conference protocols

As an important application of the quantum network communication,quantum multiparty conference has made multiparty secret communication possible.Previous quantum multiparty conference schemes based on quantum data encryption are insensitive to network topology.However,the topology of the quantum network significantly affects the communication efficiency,e.g.,parallel transmission in a channel with limited bandwidth.We have proposed two distinctive protocols,which work in two basic network topologies with efficiency higher than the existing ones.We first present a protocol which works in the reticulate network using Greeberger-Horne-Zeilinger states and entanglement swapping.Another protocol,based on quantum multicasting with quantum data compression,which can improve the efficiency of the network,works in the star-like network.The security of our protocols is guaranteed by quantum key distribution and one-time-pad encryption.In general,the two protocols can be applied to any quantum network where the topology can be equivalently transformed to one of the two structures we propose in our protocols.     

Quantum Secure Communication Using a Class of Three-Particle W State

A theoretical scheme of quantum secure communication using a class of three-particle W states is proposed. In the scheme, two communicators may communicate after they test the security of the quantum channel. The receiver can obtain the secret message determinately if the quantum channel is safe. The present scheme can be realized without using teleportation.     

Efficient quantum secure communication scheme with one-time pad

In this paper, we proposed a novel quantum secure direct communication scheme with one-time pad in stabilizer formalism. Based on the reuse of qubit sequence, an efficient secure communication of secret messages without first producing a shared secret key can be achieved. One hence may find that the amount of private key needed for quantum communication is smaller than that in the general case. Therefore, the present protocol which is feasible with the present-day techniques may be applied to quantum communication with short-length encoding.     

Quantum Secure Direct Communication Using W State

A theoretical scheme of quantum secure direct communication using teleportation is proposed. In the scheme, the sender needs to prepare a class of three-particle W states to use as quantum channel. The two communicators may communicate after they test the security of the quantum channel. The security of the protocol is ensured by quantum entanglement and quantum no-cloning theorem. The receiver can obtain the secret message determinately if the quantum channel is secure.     

A Three-Stage Quantum Cryptography Protocol

We present a three-stage quantum cryptographic protocol based on public key cryptography in which each party uses its own secret key. Unlike the BB84 protocol, where the qubits are transmitted in only one direction and classical information exchanged thereafter, the communication in the proposed protocol remains quantum in each stage. A related system of key distribution is also described.     

Efficient quantum secure communication with a publicly known key

This paper presents a simple way for an eavesdropper to eavesdrop freely the secret message in the experimental realization of quantum communication protocol proposed by Beige et al （2002 Acta Phys. Pol. A 101 357）. Moreover, it introduces an efficient quantum secure communication protocol based on a publicly known key with decoy photons and two biased bases by modifying the original protocol. The total efficiency of this new protocol is double that of the original one. With a low noise quantum channel, this protocol can be used for transmitting a secret message. At present, this protocol is good for generating a private key efficiently,     

A Novel Deterministic Quantum Communication Scheme Using Stabilizer Quantum Code

Exploiting the encoding process of the stabilizer quantum code [[n, k, d]], a deterministic quantum communication scheme, in which n - 1 photons are distributed forward and backward in two-way channel, is proposed to transmit the secret messages with unconditional security. The present scheme can be implemented to distribute the secret quantum （or classical） messages with great capacity in imperfect quantum channel since the utilized code encodes k-qubit messages for each scheme run.     

量子密钥分发与量子安全直接通信

量子通信具有高安全性等优点,是当前的国际研究前沿,量子安全直接通信和量子密钥分发是两种重要的量子信息方式.量子密钥分发通过量子信道产生随机的密钥,而量子安全直接通信直接在量子信道中传输秘密信息.本文力图利用浅显易懂的语言介绍量子安全直接通信和量子密钥分发的基本原理;重点描述几个典型的量子安全直接通信方案,介绍目前的发展状态并展望未来.     

Quantum Secret Sharing Based on Chinese Remainder Theorem

A novel quantum secret sharing (QSS) scheme is proposed on the basis of Chinese Remainder Theorem (CRT). In the scheme, the classical messages are mapped to secret sequences according to CRT equations, and distributed to different receivers by different dimensional superdense-coding respectively. CRT's secret sharing function,together with high-dimensional superdense-coding, provide convenience, security, and large capability quantum channel forsecret distribution and recovering. Analysis shows the security of the scheme.