Measurement-device-independent quantum cryptographic conferencing with an untrusted source

Measurement-device-independent quantum cryptographic conferencing(MDI-QCC) protocol puts MDI quantum key distribution(MDI-QKD) forwards to multi-party applications, and suggests a significant framework for practical multi-party quantum communication. In order to mitigate the experimental complexity of MDI-QCC and remove the key assumption(the sources are trusted) in MDI-QCC, we extend the framework of MDI-QKD with an untrusted source to MDI-QCC and give the rigorous security analysis of MDI-QCC with an untrusted source. What is more, in the security analysis we clearly provide a rigorous analytical method for parameters' estimation, which with simple modifications can be applied to not only MDI-QKD with an untrusted source but also arbitrary multi-party communication protocol with an untrusted source. The simulation results show that at reasonable distances the asymptotic key rates for the two cases(with trusted and untrusted sources) almost overlap, which indicates the feasibility of our protocol.     

子波谱方法在三维声辐射和声散射中的应用

将边界变量用二维子波展开,获得了三维任意边界条件声辐射和声散射的边界积分方程的子波谱方法.采用以子波为权函数的Gauss积分法计算子波谱方法的系数,获得了与传统边界元法相同的计算量,克服了普通积分法计算子波系数计算量大甚至难以收敛的缺点;采用Duffy的方法解决了子波谱方法中的奇异积分,使其能够用普通的Gauss积分法计算.算例表明:子波谱方法系数矩阵压缩率超过50%以后,计算精度仍然高于传统边界元方法.     

Chain Inequality Violation with Quantum Weak Measurement Technology

Bell inequality is an important resource in the quantum information theory, which can be applied to guarantee security of the device independent quantum information protocols. By utilizing the quantum weak measurement technology, we propose the Chain inequality violation with three parties, and the analysis result demonstrates that double Chain inequality violation can be observed in the case of Alice and Bob have two different measurement bases.Since the weak measurement model can be assumed to be an eavesdropping model, our analysis model may be applied to analyze security of the device independent quantum information protocols.     

A new chaotic system and its circuit realization

Based on the Lü system, a new chaotic system is constructed, which can generate a Lorenz-like attractor, Chen-like attractor, Lü-like attractor and new attractor when its parameters are chosen appropriately. The detailed dynamical behaviours of this system are also investigated, including equilibria and stability, bifurcations, and Lyapunov exponent spectrum. Moreover, a novel analogue circuit diagram is designed for the verification of various attractors.     

COULOMB BLOCKADE OSCILLATIONS OF Si SINGLE-ELECTRON TRANSISTORS

Coulomb blockade oscillations of Si single-electron transistors, which are fabricated completely by the conventional photolithography technique, have been investigated. Most of the single-electron transistors clearly show Coulomb blockade oscillations and these oscillations can be periodic by applying negative voltages to the in-plane gates. A shift of the peak positions is observed at high temperatures. It is also found that the fluctuation of the peak spacing cannot be neglected.     

SINGLE-ELECTRON TRANSISTORS FOR FUTURE APPLICATIONS

Single electron transistors with wire channels are fabricated by a nanoelectrode-pair technique. Their characteristics strongly depend on the channel widths and the voltages on the in-plane gates. A few dips in the Coulomb blockade oscillations were observed at the less positive gate voltages for a device with a 70nm-wide wire due to Coulomb blockade between the coupled dots. By applying negative voltages to the in-plane gates, the oscillations became periodic, which indicated the formation of a single dot in the conducting channel. These gates facilitate fabricating single-electron transistors with single dot structures, which have potential applications on its integration.     

Fast implementation of length-adaptive privacy amplification in quantum key distribution

Post-processing is indispensable in quantum key distribution(QKD), which is aimed at sharing secret keys between two distant parties. It mainly consists of key reconciliation and privacy amplification, which is used for sharing the same keys and for distilling unconditional secret keys. In this paper, we focus on speeding up the privacy amplification process by choosing a simple multiplicative universal class of hash functions. By constructing an optimal multiplication algorithm based on four basic multiplication algorithms, we give a fast software implementation of length-adaptive privacy amplification. "Length-adaptive" indicates that the implementation of privacy amplification automatically adapts to different lengths of input blocks. When the lengths of the input blocks are 1 Mbit and 10 Mbit, the speed of privacy amplification can be as fast as 14.86 Mbps and 10.88 Mbps, respectively. Thus, it is practical for GHz or even higher repetition frequency QKD systems.     

利用超高速撞击产生的等离子体测量微粒速度的方法研究

超高速微粒在与靶物质撞击时会形成瞬时的等离子体.本文首次设计出两种传感器收集等离子体获取微粒到达传感器的时间,然后通过飞行时间法测量超高速微粒的速度.在等离子体驱动微小碎片加速器上开展了原理实验,采集到了微粒撞击产生的等离子体信号,测量到了超高速微粒的速度,验证了这种时间测量精度高、信噪比高的全新超高速微粒速度的测量方法.     

关于矩阵An的特征值的研究

从一道线性代数习题出发,举例说明常见教材中关于由矩阵A的特征值确定ψ(A)的特征值的结论不够完备,进而分析问题关键,运用求解特征多项式的方法推导出矩阵多项式的特征值.     

基于小波基函数插值的界面裂纹分析方法

利用小波的高分辨率和具有紧支性的特点将小波插值基函数引入到界面裂纹分析 ,针对裂纹面的应力奇异特点 ,采用了不同分辨率的插值方法 ,提出了基于广义变分原理的小波计算格式 ,并通常计算实例对所提方法进行验证