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在连续变量量子密钥分发系统中,同步技术是确保通信双方时钟和数据一致的关键技术.本文通过巧妙设计发送端和接收端仪器的硬件时序,采用时域差拍探测方式和峰值采集技术,实验实现了可硬件同步的四态离散调制连续变量量子密钥分发.通信双方在设计好的硬件同步时序下可实现时钟的恢复和数据的自动对齐,无需借助软件算法实现数据的对齐.本文采用了加拿大滑铁卢大学Norbert Lütkenhaus研究组提出的针对连续变量离散调制协议的安全密钥速率计算方法.该方法需计算出接收端所测各种平移热态的一阶矩和二阶(非中心)矩,以此为约束条件结合凸优化算法可计算出安全密钥速率.计算过程中无需假设信道为线性信道,无需额外噪声的估算.密钥分发系统重复频率为10 MHz,传输距离为25 km,平均安全密钥比特率为24 kbit/s.本文提出的硬件同步方法无需过采样和软件帧同步,减小了系统的复杂度和计算量,在一定程度上降低了系统所需的成本、功耗和体积,有效地增强了连续变量量子密钥分发的实用性. 相似文献
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往返式离散调制连续变量量子密钥分发,无需使用两台独立的激光器也能本地生成本振光,并且信号光与本振光均来自于同一台激光器,在有效保证系统实际安全性的同时,具有较好的同频特性.此外,该方案与高效纠错码具有良好的兼容性,即使在低信噪比情况下也能获得较高的协商效率.然而,基于非可信信源模型的往返式光路结构存在较大的过噪声,严重限制离散调制方案的最大传输距离.针对这个问题,本文提出基于非高斯态区分探测的往返式离散调制连续变量量子密钥分发方案,即在探测端部署非高斯态区分探测器,采用自适应测量方法并结合贝叶斯推论,可以在满足低于标准量子极限错误概率的情况下无条件区分出基于四态离散调制的四种非正交相干态.本文详细分析了所提出的基于非高斯态区分探测的往返式离散调制连续变量量子密钥分发方案的安全性,包括渐近情况与有限长效应情况.仿真结果表明所提出的方案相比于原始方案,即使在有信源噪声的情况下,其密钥率与最大传输距离仍然有明显的提升.这些结果表明本方案能够有效降低往返式离散调制连续变量量子密钥分发方案中非可信信源噪声对方案性能的负面影响,在保证系统实际安全性的同时,实现更高效、更远传输距离的量子密钥分发. 相似文献
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量子密钥分发融合经典通信方案将连续变量量子密钥分发和经典通信合并到了一起,为将来在现有的光网络上同时进行密钥分发和经典通信提供了一个有效的方法.然而,在量子信号上叠加一个经典信号将会给连续变量量子密钥分发系统引入过噪声从而大大降低系统的性能.本文提出基于光前置放大器的量子密钥分发融合经典通信方案,即在接收端插入光前置放大器来提升系统的性能.首先,在相同比特误码率条件下,光前置放大器对信号的放大能够降低对发送端经典信号调制振幅的要求,从而降低经典信号对量子信号的噪声影响;其次,光前置放大器能够补偿接收端探测器的不完美;再次,对于本地本振光的情形,放大器还能放大弱相位参考脉冲,从而降低参考脉冲散粒噪声带来的相位过噪声.在实际可达到的系统参数下,数值仿真结果表明本文提出的方案相比于原方案在安全密钥率和传输距离上都有很好的提升.这些结果表明本方案为量子密钥分发融合经典通信方案的进一步发展和实际应用提供了一个十分有效而实用的方法. 相似文献
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真实量子密钥分发系统中不完善的单光子源和信道损耗的存在,使得现有基于弱相干态的量子密码实验在分束攻击下并不安全,诱骗信号方案能实现基于现有技术绝对安全的量子密钥分发,并能有效提高密钥分发率和安全传输距离,因此成为近年来量子通信研究的热点问题.结合现实量子密码系统的一般模型,介绍目前几种典型的诱骗信号方案以及实验进展,综述了诱骗信号方案的发展情况和最新成果,并对未来的研究方向进行了展望. 相似文献
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非正交编码协议和诱骗态方法可以有效地抵御光子数分离攻击. 由于相干叠加态中单光子成分高达90%, 常作为单光子量子比特的替代出现, 用于量子信息过程处理和计算. 本文结合非正交编码协议和诱骗态方法提出一种新的量子密钥分发方案, 光源采用相干叠加态, 推导了单光子的密钥生成速率、计数率下限和误码率的上限, 利用Matlab 模拟了无限多诱骗态情况下和有限多诱骗态情况下密钥生成速率和传输距离的关系, 得出该方案可以提升密钥生成速率并且提高安全传输距离, 验证了该方案可以进一步提高量子密钥分发系统的性能. 相似文献
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基于量子远程通信的原理, 本文借助双模压缩真空态和相干态, 提出一种连续变量量子确定性密钥分配协议. 在利用零差探测法的情况下协议的传输效率达到了100%. 从信息论的角度分析了协议的安全性, 结果表明该协议可以安全传送预先确定的密钥. 在密钥管理中, 量子确定性密钥分配协议具有量子随机性密钥分配协议不可替代的重要地位和作用. 与离散变量量子确定性密钥分配协议相比, 该协议分发密钥的速率和效率更高, 又协议中用到的连续变量量子态易于产生和操控、适于远距离传输, 因此该协议更具有实际意义. 相似文献
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This paper investigates robust unified (lag, anticipated, and complete)
synchronization of two coupled chaotic systems. By introducing the concepts
of positive definite symmetrical matrix and Riccati inequality and the
theory of robust stability, several criteria on robust synchronization are
established. Extensive numerical simulations are also used to confirm the
results. 相似文献
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In this paper, the
proportional synchronization between drive system and response
system is achieved by using the concept of generalized
synchronization. The phase space of all variables in response
system can be expanded and compressed flexibly. Meanwhile, the 6-D
hyperchaotic chua's circuit is considered as an illustrative
example to demonstrate the effectiveness of the proposed approach.
Furthermore, focusing on the shortcoming of the long transient
behavior during the process of synchronization, a feedback method
is adopted to shorten the transitional time of synchronization,
which will provide an effective way for speeding up the
transmitting velocity of code in chaotic multiple access communication. 相似文献
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Adaptive generalized functional synchronization of chaotic systems with unknown parameters 下载免费PDF全文
A universal adaptive generalized functional synchronization approach to any two different or identical chaotic systems with unknown parameters is proposed, based on a unified mathematical expression of a large class of chaotic system. Self-adaptive parameter law and control law are given in the form of a theorem. The synchronization between the three-dimensional R6ssler chaotic system and the four-dimensional Chen's hyper-chaotic system is studied as an example for illustration. The computer simulation results demonstrate the feasibility of the method proposed. 相似文献
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In this paper, a new method for controlling projective synchronization in coupled
chaotic systems is presented. The control method is based on a partially linear
decomposition and negative feedback of state errors. Firstly, the synchronizability
of the proposed projective synchronization control method is proved mathematically.
Then, three different representative examples are discussed to verify the
correctness and effectiveness of the proposed control method. 相似文献
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YUAN Guo-Yong YANG Shi-Ping WANG Guang-Rui CHEN Shi-Gang 《理论物理通讯》2008,49(1):174-180
In this paper, we consider a model system with two identical time-delayed coupled layers. Synchronization and anti-phase synchronization are exhibited in the reactive system without diffusion term. New segmented spiral waves, which are constituted by many thin trips, are found in each layer of two identical time-delayed coupled layers, and are different from the segmented spiral waves in a water-in-oil aerosol sodium bis(2-ethylhexyl) sulfosuccinate (AOT) microemulsion (ME) (BZ-AOT system), which consists of many small segments. "Anti-phase spiral wave synchronization" can be realized between the first layer and the second one. For different excitable parameters, we also give the minimum values of the coupling strength to generate segmented spiral waves and the tip orbits of spiral waves in the whole bilayer. 相似文献
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This paper investigates the function cascade synchronization of
chaos system. Combining cascade synchronization scheme, parametric
adaptive control and projective synchronization scheme, it proposes
a new function cascade synchronization scheme to address a
generalized-type synchronization problem of three famous chaotic
systems: the Lorenz system, Liu system and R\"{o}ssler system, the
states of two identical chaotic systems with unknown parameters can
be asymptotically synchronized by choosing different special
suitable error functions. Numerical simulations are used to verify
the effectiveness of the proposed synchronization techniques. 相似文献
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Phase synchronization and its transition in two coupled bursting neurons: theoretical and numerical analysis 下载免费PDF全文
It is crucially important to study different synchronous
regimes in coupled neurons because different regimes may correspond
to different cognitive and pathological states. In this paper, phase
synchronization and its transitions are discussed by means of
theoretical and numerical analyses. In two coupled modified
Morris--Lecar neurons with a gap junction, we show that the occurrence
of phase synchronization can be investigated from the dynamics of
phase equation, and the analytical synchronization condition is
derived. By defining the phase of spike and burst, the transitions
from burst synchronization to spike synchronization and then toward
nearly complete synchronization can be identified by bifurcation
diagrams, the mean frequency difference and time series of neurons.
The simulation results suggest that the synchronization of bursting
activity is a multi-time-scale phenomenon and the phase
synchronization deduced by the phase equation is actually spike
synchronization. 相似文献
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This paper investigates the function cascade synchronization of chaos system. Combining cascade synchronization scheme, parametric adaptive control and projective synchronization scheme, it proposes a new function cascade synchronization scheme to address a generalized-type synchronization problem of three famous chaotic systems: the Lorenz system, Liu system and RSssler system, the states of two identical chaotic systems with unknown parameters can be asymptotically synchronized by choosing different special suitable error functions. Numerical simulations are used to verify the effectiveness of the proposed synchronization techniques. 相似文献
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The dynamics of two uncoupled distinct Chua circuits driven by a common direct current voltage is explored experimentally.
It was found that, with increasing current intensity, the dominant frequencies of these two Chua circuits will first vary
at different speeds, approach an identical value for a certain current intensity and then separate. Techniques such as synchronization
index and phase difference distribution were employed to analyze the phase coherence between these two Chua circuits. 相似文献