一种可控量子隐形传态身份认证的方案

提出了一种实现可控量子隐形传态身份认证的方案.可信第三方Charlie利用纠缠交换原理对接收者Bob进行身份认证,在确定Bob的合法身份并将消息反馈给发送者Alice后,Alice再对量子信息进行传送.本方案能有效解决假冒身份攻击,从而保证量子信息传送的安全性.     

利用三粒子GHZ态实现令牌环量子隐形传态网络

研究了三纠缠粒子量子隐形传态网络的物理基础,得到了基于三粒子GHZ态下隐形传态的幺正变换矩阵,设计了一个基于三纠缠粒子的令牌环量子隐形传态网络,给出了一个基于该网络的通信方案.笔者设计的网络中的各站点可实现任意站点间的量子通信,其监控站还可对整个网络的通信情况进行监控和计费管理.     

基于EPR粒子对的信息签名协议

研究了利用Einstein-Podolsky-Rosen (EPR)对的纠缠特性进行量子数字签名的方案,提出了一个基于测量结果比较的签名协议以及一个基于隐形传态的签名协议. 在基于测量结果比较的签名协议中,通信双方测量各自的EPR并将测量结果与消息M进行比较可以实现M的签名和验证,同时通过量子单向函数来保证协议的安全. 在基于隐形传态的签名协议中,消息发送者将M通过隐形传态传递给接收者来实现对M签名并验证,其安全性由量子隐形传态的物理特性来保证. 这两种协议均可以脱离可信赖的第三方,且通信过程中不需要密钥,具有无条件安全性.     

三粒子W纠缠态的概率量子隐形传态

提出一个对未知三粒子W纠缠态的量子隐形传态方案.该方案用一个非最大GHZ纠缠态和一个非最大EPR纠缠态作为量子信道实现对未知经典W纠缠态的概率量子隐形传态和对未知一般W纠缠态受控的概率量子隐形传态.     

基于量子隐形传态局域网通信的身份认证

多用户在同一通信终端通信认证时,由于用户之间没有明确的优先级别限制,在相同时间内“盲目竞争”获取认证信息,造成经典信道拥堵.为了避免因通信用户之间的冲突或闲置带来的网络资源的浪费,结合令牌环技术和量子隐形传态通信技术,提出了量子隐形传态局域网内各通信站点间实现优先级预约及身份信息核实的认证方案.此方案可实现通信网络的规范有序运行,减少网络资源的浪费,缩短通信时延,提高身份认证效率.     

多体纠缠相干态的量子隐形传输

提出了一种适用于多体纠缠相干态的量子隐形传态方案，利用分光仪等光学器件，通过简单的么正交换和两体态上的光子数的测量，实现了多体纠缠态的量子隐形传输。     

首科园地

百公里远距离量子通信既保密又安全日前,由清华大学、中国科技大学等机构组成的联合研究团队,在远距离量子通信研究上取得重大突破,在国际上率先实现绝对安全距离大于100公里的量子保密通信。科学家们采用诱骗信号方法在国际上率先实现了以弱激光为光源、绝对安全距离大于100公里的量子密钥分发。这是我国科学家继五光子纠缠态制备与操纵、自由空间量子纠缠分发以及复合体系量子态隐形传输等重要研究成果后,在量子通信实验领域取得的又一国际领先的研究成果。植物无糖组培环境控制技术取得突破北京科技协作中心协办日前,由中国农业科学院农…     

一种改进的通信保密技术研究

传统的通信加密算法采用量子密码学方法,把量子通信系统当作一个有限的时间序列,进行信息加密处理,随着通信数据量的逐渐增多,量子密码加密算法会产生破译风险,加密性能不好。本文提出了基于量子通信隐形状态深层次特征加密的通信保密技术。进行量子保密通信循环码加密模型构建,对量子保密通信循环码比特序列进行特征提取和检测设计,信道估计采用时频二维的导频辅助信道估计,按照OFDM信号的数据帧进行向量估计,围绕数据包数量、数据内容重复率、邻域节点数据相似度和相关性来分析恶意的数据分发行为,计算量子隐形传态链路层重加密钥,采用标量时间序列进行终端密文认证,实现加密通信技术改进。仿真结果表明,采用该模型能有效实现通信保密,保密控制性能较好,增强了数据加密的随机性,实现通信保密优化数据传输,保证信息安全。     

基于双向量子隐形传态上的双向量子安全直接通信

提出了一种利用EPR对和纠缠交换的双向量子隐形传态;在这个协议中,双方可同时发送一个未知的单一量子比特给对方,而且在实际操作中比以前的提出的协议更加简单;利用提出的双向量子隐形传态,建立了一种新的双向量子安全直接通信协议,协议在通信过程中不需要传递携带秘密信息的量子比特,大大提高了量子通信的安全信.     

基于纠缠交换协议的令牌环局域网络传输模型

针对多节点在局域网中的量子保密通信,建立了一种基于纠缠交换协议的令牌环局域网络传输模型。该模型结合纠缠交换协议,通过引入令牌环原理,进而使得量子无线基站可以在确定的时隙内分发纠缠资源给2个节点,进行无冲突通信。分析了网络的性能,推导得到了网络信息吞吐率与量子隐形传态成功概率和信道纠缠度之间的关系,通过MATLAB仿真实验对吞吐率的数值进行了分析,证明该模型的可行性,结果表明:提高通信双方建立纠缠资源、Bell态测量及成功接收测量信息的概率以及缩短信息的传输时间和优化信道的质量提高信道的纠缠度,可以增加网络的吞吐率,能有效满足量子通信的保密需求,对该领域的后续研究具有一定的参考价值。     

非经典光场及其在量子信息中的应用

扼要介绍连续变量纠缠态光场产生的实验方法,及其在量子离物传态,量子密集编码,受控密集编码,量子纠缠交换及量子通信网络中的应用.     

基于纠缠交换的量子密钥分发

为了提高量子密钥分发的效率,提出了一种基于纠缠交换的密钥分配方案。该方案无需交换经典信息且不要进行任何酉操作,通信双方通过纠缠交换并利用贝尔测量即可生成密钥;除去少量用于检测量子信道安全的量子位,其余量子位都可以用来生成密钥,且每两对纠缠粒子就可以生成密钥的两个比特位。利用Stinespring Dilation定理证明了该方案的安全性并给出了效率分析。     

基于纠缠交换的量子身份认证系统

提出了一个量子身份认证方案,该方案是基于量子EPR纠缠对的纠缠交换,并通过认证中心进行身份认证.方案的安全性由量子不可克隆性等来保证.     

腔QED中三粒子W态的隐形传递

首先,针对传递三粒子w态的困难,提出了腔QED中的两种方案来完成w态的隐形传态．在一种方案中,我们利用一个EPR对和GHZ态来作为量子通道,在真空腔中实现了对w态的传送．而第二种方案与第一种不同之处是,我们使用了两个EPR对来作为量子通道,并且弓l入了一个附加粒子来完成传态的．此外,这些方案的显著优点是不用Bell基测量,而且可忽略腔场热作用和腔延迟作用的影响．     

Multiparty quantum secret sharing of classical and quantum messages

A scheme for multiparty quantum secret sharing of classical and quantum messages is proposed by using entanglement swapping. This scheme can distribute not only the classical information but also the quantum information between N agents. The security of our scheme is also confirmed.     

Multiparty quantum secret sharing of classical and quantum messages

A scheme for multiparty quantum secret sharing of classical and quantum messages is proposed by using entanglement swapping. This scheme can distribute not only the classical information but also the quantum information between N agents.The security of our scheme is also confirmed.     

Quantum teleportation and entanglement distribution over 100-kilometre free-space channels

Transferring an unknown quantum state over arbitrary distances is essential for large-scale quantum communication and distributed quantum networks. It can be achieved with the help of long-distance quantum teleportation and entanglement distribution. The latter is also important for fundamental tests of the laws of quantum mechanics. Although quantum teleportation and entanglement distribution over moderate distances have been realized using optical fibre links, the huge photon loss and decoherence in fibres necessitate the use of quantum repeaters for larger distances. However, the practical realization of quantum repeaters remains experimentally challenging. Free-space channels, first used for quantum key distribution, offer a more promising approach because photon loss and decoherence are almost negligible in the atmosphere. Furthermore, by using satellites, ultra-long-distance quantum communication and tests of quantum foundations could be achieved on a global scale. Previous experiments have achieved free-space distribution of entangled photon pairs over distances of 600?metres (ref. 14) and 13?kilometres (ref. 15), and transfer of triggered single photons over a 144-kilometre one-link free-space channel. Most recently, following a modified scheme, free-space quantum teleportation over 16?kilometres was demonstrated with a single pair of entangled photons. Here we report quantum teleportation of independent qubits over a 97-kilometre one-link free-space channel with multi-photon entanglement. An average fidelity of 80.4?±?0.9 per cent is achieved for six distinct states. Furthermore, we demonstrate entanglement distribution over a two-link channel, in which the entangled photons are separated by 101.8?kilometres. Violation of the Clauser-Horne-Shimony-Holt inequality is observed without the locality loophole. Besides being of fundamental interest, our results represent an important step towards a global quantum network. Moreover, the high-frequency and high-accuracy acquiring, pointing and tracking technique developed in our experiment can be directly used for future satellite-based quantum communication and large-scale tests of quantum foundations.     

一次量子通信量子密钥分发和认证协议的安全性分析

分析了一次量子通信量子密钥分发（QKD）和认证（QA）协议存在的安全性漏洞,协议能抵抗截取／重发攻击策略和纠缠攻击策略,但不能抵抗纠缠／截取攻击策略,严格意义上说,在有信道噪声情况下,仅通过一次量子通信不能实现QKD和QA,根据原协议的条件,提出了2个新协议：①直接测量共享的GHZ态;②通过在原协议中加入检测过程以抵抗纠缠／截取攻击策略。     

Experimental demonstration of a BDCZ quantum repeater node

Quantum communication is a method that offers efficient and secure ways for the exchange of information in a network. Large-scale quantum communication (of the order of 100 km) has been achieved; however, serious problems occur beyond this distance scale, mainly due to inevitable photon loss in the transmission channel. Quantum communication eventually fails when the probability of a dark count in the photon detectors becomes comparable to the probability that a photon is correctly detected. To overcome this problem, Briegel, Dür, Cirac and Zoller (BDCZ) introduced the concept of quantum repeaters, combining entanglement swapping and quantum memory to efficiently extend the achievable distances. Although entanglement swapping has been experimentally demonstrated, the implementation of BDCZ quantum repeaters has proved challenging owing to the difficulty of integrating a quantum memory. Here we realize entanglement swapping with storage and retrieval of light, a building block of the BDCZ quantum repeater. We follow a scheme that incorporates the strategy of BDCZ with atomic quantum memories. Two atomic ensembles, each originally entangled with a single emitted photon, are projected into an entangled state by performing a joint Bell state measurement on the two single photons after they have passed through a 300-m fibre-based communication channel. The entanglement is stored in the atomic ensembles and later verified by converting the atomic excitations into photons. Our method is intrinsically phase insensitive and establishes the essential element needed to realize quantum repeaters with stationary atomic qubits as quantum memories and flying photonic qubits as quantum messengers.