基于Bell态与其纠缠性质的量子密钥分发

为了提高量子密钥分发的可行性、安全性和效率,在通信双方间通过构建经典信道和量子信道,提出了一种基于Bell态与其纠缠性质的量子密钥分发协议.该协议可行、安全、简单有效,通过严格的数学推导证明了窃听者不可能获取密钥而不被发现.此外,得出了该协议效率与安全的数学模型,并通过MATLAB仿真分析了协议效率与安全的关系.     

基于BB84的多用户量子密钥分发协议

BB84协议是目前最接近实用化的量子密钥分发(QKD)协议。点对点的量子密钥分发系统已经可以商用,但现有的多用户量子密钥分发协议都是采用量子纠缠、量子存储等技术手段进行密钥分发,在现有的技术条件下只能停留在理论阶段,离工程应用还有较长的距离。该文提出了一种基于BB84的多用户量子密钥分发协议,将计算机通信技术应用到量子保密通信中,实现一对多的量子通信网络的量子密钥分发,并从理论和实验结果两方面分析其可行性。     

基于QCircuit的BB84窃听仿真与分析

该文研究量子线路模型仿真量子密钥分配协议.基于QCircuit软件运用量子线路模型设计不同攻击模型下的BB84量子密钥分配协议仿真模型,并引入rsec和I(α,E)两个指标,设计指标分析线路模型,仿真分析了不同噪声信道模型下BB84密钥分配协议在P/P、B/P和B/B三种不同截取/重发策略下的有效性及安全性.仿真结果表...     

一种基于BB84协议的量子密钥分配改进方案

针对BB84协议对存在窃听的有噪信道中进行量子密钥分配效率不高的问题, 提出一种改进方案。新方案在发送方与接收方都加入类似签名的过程, 能够很好地判断窃听的存在, 并且窃听者只能获取少量的密钥信息, 在保障传输过程安全的同时, 提高了量子密钥分配的效率。     

基于GHZ态的量子密钥分发协议

摘要：在用户与用户进行量子密钥分发的时候,随着用户数量的增加,用户之间需要建立大量的量子传输信道。基于减少量子传输信道数量问题,本文设计了一种基于GHZ态的量子密钥分发协。该协议由第三方进行粒子分配,利用三粒子GHZ态在Z基和X基下具有不同的表示的特性作为密钥分发的关键点。协议中由第三方向任意两名用户分发密钥,大大减少了量子信道的数量。经过安全性分析,本协议能抵御截获重发攻击,中间人攻击和纠缠攻击,而作为第三方可以是不可信的。     

量子LDPC码在BB84协议中的应用研究

针对BB84量子密钥分配协议中量子信道存在噪声,设计一种带有量子纠错码的改进的BB84协议模型,在模型中用量子低密度奇偶校验码（量子LDPC）作为纠错码对发送量子态进行编码。通过数值仿真,从密钥传输效率的角度分析量子纠错编码对BB84协议的影响。结果表明量子LDPC码能克服噪声,提高了密钥传输效率,验证了在含噪量子信道中改进的BB84协议模型的有效性。     

BB84协议安全判据的实用标准研究

BB84协议是针对单光子量子通信提出的经典协议。在BB84协议安全判据理论值的基础上,结合窃听者所付出成本与其所得信息价值的关系,对自由空间和光纤2种量子信道,分别提出了各自的BB84协议安全判据的实用标准。     

基于BB84协议的空间量子通信系统

我们分析了基于BB84协议的空间量子通信系统.该系统使用大气量子信道,以因特网为经典信道.讨论了光子与大气的相互作用,利用量子计算语言对大气信道中的量子密钥分配进行了仿真.将用于量子计算仿真的语言引入量子通信的研究中,讨论了单光子脉冲系统与纠缠光子对系统的特点,分析了全球量子通信系统的可行性.     

解析量子密钥分配中量子LDPC码的应用

将BB84密钥分配协议看做一个Wire-tap的信道模型,其主信道为二进制对称信道,比特翻转率为025ε,窃听信道是二进制删除信道,删除概率为1-ε.通过量子LDPC编码方式,BB84编写实现主信道的安全通信,同时对BB84协议的安全性进行证明.最后,对Wire-tap信道的安全容量进行计算,最终得到BB84协议下量子LDPC码的可容忍误码率.     

一种基于[7,1]CSS纠错码的量子密钥分配协议

量子密钥分配协议具有可证明的绝对安全性,但是由于量子信道噪声的作用,量子比特在传输过程中容易产生错误,从而降低量子密钥分配的效率。对此,根据量子纠错理论,利用Hamming码构造一种[7,1]CSS纠错码,并结合BB84协议,提出一种改进的量子密钥分配协议。通过理论分析与数值计算,对比改进协议与BB84协议在含噪声量子信道中的传输错误率,结果表明改进的量子密钥分配协议相比于BB84协议提高了对信道噪声的抵抗能力。     

Unambiguous State Discrimination in Quantum Key Distribution

The quantum circuit and design are presented for an optimized entangling probe attacking the BB84 Protocol of quantum key distribution (QKD) and yielding maximum information to the probe. Probe photon polarization states become optimally entangled with the signal states on their way between the legitimate transmitter and receiver. Although standard von-Neumann projective measurements of the probe yield maximum information on the pre-privacy amplified key, if instead the probe measurements are performed with a certain positive operator valued measure (POVM), then the measurement results are unambiguous, at least some of the time. It follows that the BB84 (Bennett–Brassard 1984) protocol of quantum key distribution has a vulnerability similar to the well-known vulnerability of the B92 (Bennett 1992) protocol Pacs: 03.67.Dd, 03.67.Hk, 03.65.Ta     

Topical Review: Optimum Probe Parameters for Entangling Probe in Quantum Key Distribution

For the four-state protocol of quantum key distribution, optimum sets of probe parameters are calculated for the most general unitary probe in which each individual transmitted photon is made to interact with the probe so that the signal and the probe are left in an entangled state, and projective measurement by the probe, made subsequent to projective measurement by the legitimate receiver, yields information about the signal state. The probe optimization is based on maximizing the Renyi information gain by the probe on corrected data for a given error rate induced by the probe in the legitimate receiver. An arbitrary angle is included between the nonorthogonal linear polarization states of the signal photons. Two sets of optimum probe parameters are determined which both correspond to the same optimization. Also, a larger set of optimum probe parameters is found than was known previously for the standard BB84 protocol. A detailed comparison is made between the complete and incomplete optimizations, and the latter simpler optimization is also made complete. Also, the process of key distillation from the quantum transmission in quantum key distribution is reviewed, with the objective of calculating the secrecy capacity of the four-state protocol in the presence of the eavesdropping probe. Emphasis is placed on information leakage to the probe. PACS: 03.67.Dd; 03.67.Hk; 03.65.Ta     

基于BB84的量子密钥分配协议的研究

以BB84协议为基础，对其中部分内容进行了改进，并将身份认证加入到协议中，使量子密钥分配协议的安全性更高。     

BB84量子密钥分配协议在专网中的应用

依据专用网络的特点,对BB84量子密钥分配协议做了改进,提出一种适用于专用网络的BB84-PN协议。该协议通过身份认证和量子物理特性,提高了安全性。同时,在通信过程中通过协商传输量子密钥规则,有效地提高了传输效率。     

Security of Practical BB84 Quantum Key Distribution

Abstract. We propose a proof of the security of a practical BB84 quantum key distribution protocol against enemies with unlimited computational power. The considered protocol uses interactive key distillation, and the proof holds for implementations using imperfect optical devices.     

量子密码在无线局域网中的安全研究

本文通过对量子密码BB84协议及IEEE802.11i认证协议的分析与讨论,深入研究了802.11i密钥管理机制中的4次握手,利用量子密码安全的优势与IEEE802.11i无线网络相结合,提出量子握手,为无线网络中数据的通信安全提供保障。     

Efficient entanglement concentration for quantum dot and optical microcavities systems

A recent paper (Chuan Wang in Phys Rev A 86:012323, 2012) discussed an entanglement concentration protocol (ECP) for partially entangled electrons using a quantum dot and microcavity coupled system. In his paper, each two-electron spin system in a partially entangled state can be concentrated with the assistance of an ancillary quantum dot and a single photon. In this paper, we will present an efficient ECP for such entangled electrons with the help of only one single photon. Compared with the protocol of Wang, the most significant advantage is that during the whole ECP, the single photon only needs to pass through one microcavity which will increase the total success probability if the cavity is imperfect. The whole protocol can be repeated to get a higher success probability. With the feasible technology, this protocol may be useful in current long-distance quantum communications.