共查询到17条相似文献,搜索用时 140 毫秒
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量子高斯密钥分发的逆向数据协调 总被引:1,自引:0,他引:1
加密系统中Alice端通过光纤传送相干态量子信号给Bob端,得到的一系列相关的高斯连续变量,然后从中提取出二进制密钥,这一过程称作高斯连续变量量子密钥分发.其中的数据协调步骤,即对相关连续变量的错误校正,是本文的研究问题.本文在分层错误校正协议(SEC)和多电平编码/多级解码(MLC/MSD)协议的基础上,用基于LDPC码的Slepian-Wolf编译码器实现协调.根据连续变量的多级Tanner信息传输流图,本文推导了多级迭代的内信息和外信息置信传播(LLR-BP)更新公式,并用实验比较了MSD三种译码模式的收敛性质及性能.仿真结果表明该算法可在信道信噪比2.5 dB以上实现10000个连续变量序列的可靠协调,协调效率可达92.3%. 相似文献
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基于六光子量子避错码的量子密钥分发方案 总被引:3,自引:0,他引:3
量子信道中不可避免存在的噪声将扭曲被传输的信息,对通信造成危害。目前克服量子信道噪声的较好方案是量子避错码(QEAC)。将量子避错码思想用于量子密钥分发,能有效克服信道中的噪声,且无需复杂的系统。用六光子构造了量子避错码,提出了一种丛于六光子避错码的量子密钥分发(QDK)方案。以提高量子密钥分发的量子比特效率和安全性为前提,对六光子避错码的所有可能态进行组合,得到一种六光子避错码的最优组合方法,可将两比特信息编码在一个态中,根据测肇结果和分组信息进行解码,得到正确信息的平均概率为7/16。与最近的基于四光子避错码的克服量子信道噪声的量子密钥分发方案相比,该方案的量子比特效率提高了16.67%,密钥分发安全性足它的3.5倍。 相似文献
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基于连续变量GHZ态的纠缠特性,提出一种三方量子确定性密钥分配协议,其中密钥由GHZ态的振幅产生,而相位可以用来验证信道的安全性.现有的量子确定性密钥分配协议一次只能向一个接收方传送密钥,现实生活中经常要向多个接收方发送确定性密钥.信息论分析结果表明,当信道传输效率大于0.5时,该协议可以同时向两个接收方安全传送确定性密钥,制备多重纠缠态后,该协议还能够扩展成多方量子确定性密钥分配协议,这极大提高了密钥的整体传送效率,而且连续变量量子GHZ态信道容量较高,因此该协议具有重要的现实意义. 相似文献
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如何提高实际量子密钥分发系统的安全码率和最远传输距离是量子密码学领域重要的研究课题. 本文采用量子无噪线性光放大器放大量子信号, 以改进连续变量量子密钥分发系统实际性能. 经仔细研究, 本文发现增益系数为g的线性无噪放大器可将连续变量量子密钥分发系统的最远安全传输距离提高20 log10(g)/a km (a=0.2 dB/km为光纤信道的损耗系数), 并改善系统的安全码率和噪声抗性.
关键词:
量子密钥分发
连续变量
最远传输距离
线性无噪放大器 相似文献
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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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针对高斯量子密钥分发的数据协调问题,对高斯连续变量进行了最优量化,实现了Alice和Bob之间的互信息量最大。在分层错误校正(SEC)协议和多电平编码/多级解码(MLC/MSD)协议的基础上,各级码流采用了低密度奇偶校验码(LDPC)进行错误校正,并推出了一次硬信息级间迭代更新公式参与MSD译码算法。算法实现中使用双向十字链表方式存贮LDPC码的稀疏矩阵H,并用C语言实现整个数据协调过程,极大地降低了空间复杂度,提高了协调速度。实验仿真结果表明该算法可在信道信噪比4.9dB以上实现2×105个连续变量序列的可靠协调,协调效率达91.71%,在2.4GHz CPU,32G内存服务器平台上的协调速度可达7262bit/s。 相似文献
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量子纠错编码技术在量子通信和量子计算领域起着非常重要的作用.构造量子纠错编码的主要方法是借鉴经典纠错编码技术,目前几乎所有经典纠错编码方案都已经被移植到量子领域中来,然而在经典编码领域纠错性能最杰出的Turbo码却至今没有量子对应.提出了一种利用量子寄存器网络构造量子递归系统卷积码的简单实现方案,同时利用量子SWAP门设计了一种高效的量子交织器门组网络方案.最后仿照经典Turbo码的设计原理提出串行级联的量子Turbo码,同时提出了可行的译码方法.量子Turbo码不仅丰富了量子纠错码研究的领域,同时为解释
关键词:
量子递归系统卷积码
量子Turbo码
量子纠错编码
量子信息 相似文献
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Chang-Hua Zhu Dong-Xiao Quan Fang Zhang Chang-Xing Pei 《International Journal of Theoretical Physics》2013,52(2):596-603
We investigate the key rate of polarization-coded optical fiber-based quantum key distribution system (QKD) with BB84 protocol by channel tomography. The quantum bit error rate (QBER) of the QKD system under depolarizing channel is obtained by analyzing output density operators, transmission rate of channel, transmission rate of the receiver and dark count of single photon detector. According to the estimated QBER an LDPC chosen adaptively is applied to information reconciliation and the practical final key rate is discussed. Analysis results show that compared with cascade scheme and no channel knowledge the key rate can be improved by the proposed reconciliation scheme with channel tomography. 相似文献
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Quantum key distribution (QKD) is a promising technique to share unconditionally secure keys between remote parties. As an essential part of a practical QKD system, reconciliation is responsible for correcting the errors due to the quantum channel noise by exchanging information through a public classical channel. In the present work, we propose a novel syndrome-based low-density parity-check (LDPC) reconciliation protocol to reduce the information leakage of reconciliation by fully utilizing the syndrome information that was previously wasted. Both theoretical analysis and simulation results show that our protocol can evidently reduce the information leakage as well as the number of communication rounds. 相似文献
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《中国光学快报(英文版)》2019,(11)
Seeking good error correcting codes to improve the efficiency of continuous-variable quantum key distribution(CVQKD) reconciliation is a concerning issue. Due to the introduction of multidimensional reconciliation, the error correcting techniques in the classical binary-input additive white Gaussian noise channel are applicable to CVQKD. In this Letter, we apply the quasi-cyclic low-density parity-check(QC-LDPC) codes, which are specified in 5 G protocol, to the reconciliation process. Simulation results show that the reconciliation efficiency can reach 92.6% when the code rate is 22/68 and the signal-to-noise ratio is 0.623. Such a new error correcting code points out a new direction for the development of CVQKD. 相似文献
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Non-Reconciled Physical-Layer Keys-Assisted Secure Communication Scheme Based on Channel Correlation
Meng Wang Kaizhi Huang Zheng Wan Xiaoli Sun Liang Jin Kai Zhao 《Entropy (Basel, Switzerland)》2022,24(8)
Physical-layer key generation technology requires information reconciliation to correct channel estimation errors between two legitimate users. However, sending the reconciliation signals over the public channel increases the communication overhead and the risk of information leakage. Aiming at the problem, integrated secure communication schemes using non-reconciled keys have attracted extensive attention. These schemes exploit channel coding to correct both inconsistent keys and transmission error bits. Meanwhile, more redundant code bits must be added to correct errors, which results in a lower secure transmission rate. To address the problem, we analyze the merit of channel correlation between non-reconciled key generation and secure transmission. Inspired by this, we propose a non-reconciled physical-layer keys-assisted secure communication scheme based on channel correlation. First of all, the signal frame is designed to make use of channel correlation between non-reconciled key generation and secure transmission. Based on the channel correlation, non-reconciled keys are then generated from the wireless channel to encrypt transmitted data. Moreover, an adaptive coding algorithm based on the equivalent channel is presented to encode the data bits before encryption, to guarantee reliable transmission. Finally, theoretical analysis and simulations demonstrate the significant performance of the proposed scheme in terms of low bit error ratio and high secure transmission rate. 相似文献
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在连续变量量子密钥分发(CV-QKD)多维数据协调中,协调效率和密钥传输距离取决于低密度奇偶校验(LDPC)码的纠错性能。在本研究中构造了一种拥有重复累积(RA)码中累积结构的高码率双边类型LDPC码(TET-LDPC),这种双边类型LDPC码在多维数据协调中相比于普通LDPC码可以得到更好的协调性能。经仿真结果可知,在信噪比为1.68 dB时,本文构造的码长为2×10~5的TET-LDPC的协调效率仍然可以达到98.48%,并得到了17.35 kb/s的安全密钥率。 相似文献
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现有Turbo均衡采用迭代联合均衡译码结构,这一迭代过程在信噪比高于某一门限后才能产生正向的迭代增益,当信道码间干扰较为严重或者采用高阶调制方式时,该信噪比门限较高;同时,现有Turbo均衡的性能还受限于其交织器长度,故当码块长度较短时,其性能并不理想。针对以上问题,提出了一种基于Spinal码的联合均衡译码方法。首先,该方法采用非迭代的最大似然联合均衡译码结构,有效避免了Turbo均衡迭代结构所带来的信噪比门限高问题;其次,该方法采用信息混合能力更强的Spinal码,有助于提高码块长度受限时的误码率性能;最后,该方法利用Spinal码可以有效增加相似信息序列间汉明距离的特点,将联合均衡译码时间复杂度降低为仅随信息序列长度与信道响应长度呈线性增长,解决了本方法难以实际应用于实时水声通信的难题。在抚仙湖湖试中,同样实现速率为3.34kbps数据通信,该方法的误码率优于Turbo均衡方法两个数量级以上。时变水声信道下的仿真以及湖试结果表明,该方法在码长受限的情况下仍在复杂水声信道中表现出更好性能,其所需的最低输入信噪比显著低于现有Turbo均衡方法。 相似文献
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Secure deterministic communication in a quantum loss channel using quantum error correction code
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The loss of a quantum channel leads to an irretrievable particle loss
as well as information. In this paper, the loss of quantum channel is
analysed and a method is put forward to recover the particle and
information loss effectively using universal quantum error
correction. Then a secure direct communication scheme is proposed,
such that in a loss channel the information that an eavesdropper can
obtain would be limited to arbitrarily small when the code is
properly chosen and the correction operation is properly arranged. 相似文献