Quantum Bit Error Avoidance

Qubit errors might be avoided by using the quantum Zeno effect to inhibit evolution.

面向异构信号处理平台的量子调度算法

针对异构信号处理平台中已有调度算法的调度长度较大导致信号处理应用实时性下降问题,文中提出一种面向异构信号处理平台的量子调度算法。该算法采用任务优先级分流排序策略,得到更加准确的任务调度顺序。使用量子比特对任务分配方案进行编码,增加任务分配方案的多样性,且编码规则有助于跳出局部最优找到全局最优解。按照最小计算开销原则和任务复制思想进行处理器分配,减少任务间通信开销,并通过量子旋转门对量子编码方案进行更新,不断逼近最优解。仿真结果表明,所提算法能够减少调度长度,提升信号处理应用的实时性,进而提高平台的工作效率。

磁场调制下的双电子量子点qubit

研究了磁场中二维有限深抛物形量子点中双电子在总自旋分别为 S=0或 S=1时的电子态 ,在有效质量近似下 ,利用精确的对角化方法计算了系统的能级结构 .发现系统的基态总自旋 S可以通过改变磁场的大小进行调制 ,由此可以设计利用 S=0和

求解Max-Re-SAT的离散混沌量子蝙蝠算法

针对最大正则可满足性问题求解算法的研究空缺,以及提升求解最大可满足性问题的智能优化算法的精度,基于蝙蝠算法(bat algorithm,BA),提出了一种基于离散混沌量子的蝙蝠算法。在该算法中,将连续数值转化为离散的二进制编码,对算法进行了离散化处理。该研究运用量子理论、引入量子比特编码和启发式量子变异,通过量子旋转门改变非最优个体的概率振幅来实现变异,解决了早熟和收敛速度慢的问题。在位置更新中,使用混沌映射替代固定参数,增强了灵活性和多样性,提高了全局寻优能力和求解效率。实验结果表明:在随机正则可满足性问题实例产生模型产生的不同规模算例上,所提算法的求解精度远远高于传统启发式算法;同时,与获奖的求解器相比,也具有一定的竞争力,验证了该算法的有效性。

Enhanced minimum attribute reduction based on quantum-inspired shuffled frog leaping algorithm

Attribute reduction in the rough set theory is an important feature selection method, but finding a minimum attribute reduction has been proven to be a non-deterministic polynomial （NP）-hard problem. Therefore, it is necessary to investigate some fast and effective approximate algorithms. A novel and enhanced quantum-inspired shuffled frog leaping based minimum attribute reduction algorithm （QSFLAR） is proposed. Evolutionary frogs are represented by multi-state quantum bits, and both quantum rotation gate and quantum mutation operators are used to exploit the mechanisms of frog population diversity and convergence to the global optimum. The decomposed attribute subsets are co-evolved by the elitist frogs with a quantum-inspired shuffled frog leaping algorithm. The experimental results validate the better feasibility and effectiveness of QSFLAR, comparing with some representa- tive algorithms. Therefore, QSFLAR can be considered as a more competitive algorithm on the efficiency and accuracy for minimum attribute reduction.

Eavesdropping on Quantum Secure Direct Communication with W State in Noisy Channel

Security of the quantum secure direct communication protocol （i.e., the C-S QSDC protocol） recently proposed by Cao and Song [Chin. Phys. Lett. 23 （2006） 290] is analyzed in the case of considerable quantum channel noise. The eavesdropping scheme is presented, which reveals that the C-S QSDC protocol is not secure if the quantum bit error rate （QBER） caused by quantum channel noise is higher than 4.17%. Our eavesdropping scheme induces about 4.17% QBER for those check qubits. However, such QBER can be hidden in the counterpart induced by the noisy quantum channel if the eavesdropper Eve replaces the original noisy channel by an ideal one. Furthermore, if the QBER induced by quantum channel noise is lower than 4.17%, then in the eavesdropping scheme Eve still can eavesdrop part of the secret messages by safely attacking a fraction of the transmitted qubits. Finally, an improvement on the C-S QSDC protocol is put forward.

Magneto-optical properties of self-assembled InAs quantum dots for quantum information processing

Semiconductor quantum dots have been intensively investigated because of their fundamental role in solid-state quan- tum information processing. The energy levels of quantum dots are quantized and can be tuned by external field such as optical, electric, and magnetic field. In this review, we focus on the development of magneto-optical properties of single InAs quantum dots embedded in GaAs matrix, including charge injection, relaxation, tunneling, wavefunction distribution, and coupling between different dimensional materials. Finally, the perspective of coherent manipulation of quantum state of single self-assembled quantum dots by photocurrent spectroscopy with an applied magnetic field is discussed.

三格点自旋链上单比特信息传输的精确调控

引入解析求解的方法,研究格点数为3的自旋链上单比特量子信息的完美传输.在给自旋链施加格点间逐差变化的磁场后,求解出了该磁场对单比特信息完美传输所产生影响的精确解.得出结论:此磁场会对实现信息完美传输的时间条件产生至关重要的影响,该条件不再仅取决于自旋链系统自身的物理属性,且仍然与链上格点的数目无关;可根据传输需要,利用合理设置的磁场控制单比特信息完美传输的时间条件.

一种基于vizard的量子比特可视化仿真模型

为了开展量子计算的科学研究和教育教学,产生了量子计算的仿真工具。Vizard是一款虚拟现实开发平台软件,适合建立三维模型,可以用Python语言进行快速开发。基于Vizard平台,提出了一种“糖果盒”量子比特可视化仿真模型。该模型采用量子态棒棒糖描述量子比特的概率振幅,糖果半径表示模,糖棍与水平面的夹角表示辅角,打开盒盖后引起量子态棒棒糖塌缩。借助量子态棒棒糖,仿真了量子门元件,并用量子门元件搭建了量子电路。糖果盒模型比传统的布洛赫球更加容易描述量子比特的叠加态,而且通俗易懂、富有趣味性,适合量子技术的初学者和青少年的量子技术普及教育。

基于改进布谷鸟搜索算法的WSN覆盖优化策略

针对传感器节点分散不均、覆盖程度低及汇聚层Sink节点冗余等问题,设计了一种双层无线传感器网络覆盖优化方法,该方法对传统布谷鸟搜索算法进行了改进。首先,在种群初始化过程中采用了量子位Bloch球面坐标,可以保持较高的多样性;其次,针对布谷鸟搜索算法的Levy飞行寻优阶段,改进候选解更新方法,随机生成每个纵向维度的新候选解;最后,基于逐维更新贪婪评价策略进行随机游动选择。通过这些改进方式提升了布谷鸟搜索算法的迭代速度和精度,避免相同维度间的干扰。实验结果表明,该改进算法与传统布谷鸟搜索算法、外推人工蜂群算法相比,传感器节点覆盖率分别提高了1.79%和9.87%,汇聚层Sink节点冗余率降低5.13%和21.28%。

基于量子K近邻分类算法的软件应用层接口数据分析方法

由于软件应用层接口数据的分布具有星散分布的特点,因此,分析数据判断接口状态时,对应的可靠性难以得到保障。为此,本文提出基于量子K近邻分类算法的软件应用层接口数据分析方法。将接口数据的特征映射到量子比特后,使用量子态编码具体的接口数据。在分析阶段,采用交叉验证的方式确定最佳K值,并选择曼哈顿距离作为衡量数据点之间相似性的基准,设置分类中心为软件应用层接口数据分析的目标状态参数,根据量子化软件应用层接口数据与状态分类中心的距离,完成数据分析。测试结果表明,设计方法对于软件应用层接口状态的分析结果与监测值具有较高的拟合度。

Dynamical Suppression of Nonlocal Decoherence in Two-State Quantum Systems

Nonlocal decoherence of two qubits due to pure phase damping has been investigated.We have proposeda scheme to keep the entanglement of two qubits from nonlocal decoherence.By applying a series of±π pulses,nonlocaldecoherence can be thoroughly suppressed.

Performance optimization for quantum key distribution in lossy channel using entangled photons

In quantum key distribution（QKD）, the times of arrival of single photons are important for the keys extraction and time synchronization. The time-of-arrival（TOA） accuracy can affect the quantum bit error rate（QBER） and the final key rate. To achieve a higher accuracy and a better QKD performance, different from designing more complicated hardware circuits, we present a scheme that uses the mean TOA of M frequency-entangled photons to replace the TOA of a single photon. Moreover, to address the problem that the entanglement property is usually sensitive to the photon loss in practice,we further propose two schemes, which adopt partially entangled photons and grouping-entangled photons, respectively.In addition, we compare the effects of these three alternative schemes on the QKD performance and discuss the selection strategy for the optimal scheme in detail. The simulation results show that the proposed schemes can improve the QKD performance compared to the conventional single-photon scheme obviously, which demonstrate the effectiveness of the proposed schemes.

基于3种信道的量子相干动态不确定性关系研究

为探究去极化信道、比特相位翻转信道、相位阻尼信道这3种信道对量子态相干性的影响,首先基于两组规范正交基,推导出了初始态和经过这些信道后输出态的l1范数相干和的解析表达式,并研究了量子相干和在不同信道下的动态变化.研究表明,在量子信息传输过程中,可以通过改善信道环境提升量子态的相干和的表现.该结果可为量子信息处理和量子通信领域的研究提供参考.

Proof-of-principle experimental demonstration of quantum secure imaging based on quantum key distribution

We present a quantum secure imaging(QSI) scheme based on the phase encoding and weak+vacuum decoy-state BB84 protocol of quantum key distribution(QKD). It allows us to implement a computational ghost imaging(CGI) system with more simplified equipment and reconstructed algorithm by using a digital micro-mirror device(DMD) to preset the specific spatial distribution of the light intensity. What is more, the quantum bit error rate(QBER) and the secure key rate analytical functions of QKD are used to see through the intercept-resend jamming attacks and ensure the authenticity of the imaging information. In the experiment, we obtained the image of the object quickly and efficiently by measuring the signal photon counts with a single-photon detector(SPD), and achieved a secure key rate of 571.0 bps and a secure QBER of 3.99%, which is well below the lower bound of QBER of 14.51%. Besides, our imaging system uses a laser with invisible wavelength of 1550 nm, whose intensity is as low as single-photon, that can realize weak-light imaging and is immune to the stray light or air turbulence, thus it will become a better choice for quantum security radar against intercept-resend jamming attacks.

数据驱动下基于量子人工蜂群的K均值聚类算法优化

该文将量子人工蜂群(Quantum artificial bee colony,QABC)算法用于K均值(K-means)聚类的类别中心点选择,优化K均值聚类算法,可有效解决因随机设置K均值中心点而导致聚类准确度不高的问题。该文设置K均值聚类类别数,并随机设置若干类别中心,采用人工蜂群(Artificial bee colony,ABC)算法优化类别中心点,根据待聚类样本点构建蜜蜂种群,并对蜂群个体位置采用量子比特表示。以样本点和中心点的距离的倒数作为ABC算法适应度,并将适应度值较高个体定义为蜜源。通过引领蜂在运动范围内的粗粒度遍历和跟随蜂的细粒度探索,不断搜寻适应度较高个体,并且更新蜜源,直至ABC算法稳定后确定较优蜜源位置为聚类中心。采用ABC优化得到的聚类中心进行K均值聚类。试验结果表明,通过合理设置ABC搜索边界,并引入蜂群位置的量子表示,可有效增强ABC对聚类中心的搜索精度。相比于常用聚类算法,QABC+K均值算法的聚类性能更优。

A Review of Quantum Cryptography Communication for Wireless Networks

We analyze the development of quantum cryptography communication,including analyze the problems lie in the existent literatures and give the resolve methods according to these problems.Then discuss the quantum cryptography communication for wireless networks and also point out the shortcoming of current research and the future of quantum wireless networks.

Practical Stabilization of Counterfactual Quantum Cryptography

A novel counterfactual quantum key distribution scheme was proposed by T.-G. Noh and a strict security analysis has been given by Z.-Q.Yin, in which two legitimate geographical separated couples may share secret keys even when the key carriers are not traveled in the quantum channel. However, there are still plenty of practical details in this protocol that haven’t been discussed yet, which are of significant importance in physical implementation. In this paper, we will give a practical analysis on such kind of counterfactual quantum cryptography in the aspects of quantum bit error rate (QBER) and stabilization. Furthermore, modified schemes are proposed, which can obtain lower QBER and will be much more robust on stabilization in physical implementation.

Clustering Algorithm of Quantum Self-Organization Network

To enhance the clustering ability of self-organization network, this paper introduces a quantum inspired self-organization clustering algorithm. First, the clustering samples and the weight values in the competitive layer are mapped to the qubits on the Bloch sphere, and then, the winning node is obtained by computing the spherical distance between sample and weight value. Finally, the weight values of the winning nodes and its neighborhood are updated by rotating them to the sample on the Bloch sphere until the convergence. The clustering results of IRIS sample show that the proposed approach is obviously superior to the classical self-organization network and the K-mean clustering algorithm.

浅谈超导量子比特封装与互连技术的研究进展

基于超导量子电路的量子计算技术已经在退相干时间、量子态操控和读取、量子比特间可控耦合、中大规模扩展等关键技术上取得大量突破,成为构建通用量子计算机和量子模拟机最有前途的候选技术路线之一。在介绍超导量子比特原理的基础上,结合自主创新成果,对国内外超导量子比特封装与互连技术的发展进行评价,并重点探讨了超导量子比特三维集成封装解决方案以及与外部稀释制冷机测控线路的高密度互连方案,为尽快缩小与国外超导量子计算机的差距提供超导量子比特封装与互连技术支撑。