加权量子搜索算法及其相位匹配条件研究

目前的Grover算法在无序数据库中搜索多个目标时,得到不同目标的几率是相等的,不考虑各个目标重要程度的差异;并且当目标数超过数据库记录总数的四分之一时,搜索到目标的几率迅速下降,当目标数超过记录总数的一半时,算法失效.针对这两个问题,首先提出一种基于加权目标的搜索算法.根据各子目标的重要程度,为每个子目标赋予一个权系数,应用这些权系数将多个子目标表示成一个量子叠加态,这样可使得到每个子目标的几率等于其自身的权系数;其次,提出自适应相位匹配条件,该条件中两次相位旋转的方向相反,大小根据目标量子叠加态和系统初始状态的内积决定.当该内积大于等于((3-√5)/8)^1/2时,至多只需两步搜索,即可以恒等于1的几率得到搜索目标.实验表明,算法及其相位匹配条件是有效的.     

A Remot Sensing Image Compression Method Based on Wavelet Transformation/Vector Quantization

1.IntroductionVectorquantizationprovidesameansofconvertingthedecomposedsignalintobitsinamannerthattakesadvantageofremaininginter--andinter--bandcorrelationaswellasofthemoreflexiblepartitionsofhigherdimensionalvectorspaces.TheimagecompressionmethodofWT VQhasbeenappliedinmanydigitalimageprocessingfields.SubbandcodingwasintroducedbyCroisieretal.inspeechcodingin197611].Croisieretal.firstsolvedthecriticalproblemofaliasingcancellationaf:erdecimationandreconstructioninsubbands,using"Quadraturemirr…     

超对称电动力学系统的Faddeev-Senjanovic量子化

用Faddeev-Senjanovic量子化方法对超对称电动力学系统在一般情况下进行了量子化, 得到了格林函数的生成泛函. 通过对一些约束作线性组合获得了另一个第一类约束, 构造出了该体系的规范生成元, 导出了该系统的规范不变的对称变.由一个规范条件的自恰性导出了另一个规范条件, 发现超对称电动力学系统的次级第一类约束对应物理电荷守恒律, 从而使过去要算很多次级约束才能截断的约束自然截断, 因而使超对称电动力学系统在一般情况下的Faddeev-Senjanovic量子化被简化.     

Dense coding scheme using superpositions of Bell-states and its NMR implementation

Dense coding using superpositions of Bell-states is proposed. The generalized Grover's algorithm is used to prepare the initial entangled states, and the reverse process of the quantum algorithm is used to determine the entangled state in the decoding measurement. Compared with the previous schemes, the superpositions of two Bell-states are exploited. Our scheme is demonstrated using a nuclear magnetic resonance (NMR) quantum computer. The corresponding manipulations are obtained. Experimental results show a good agreement between theory and experiment. We also generalize the scheme to transmit eight messages by introducing an additional two-state system.     

一种矢量量化编码的快速搜索算法

提出了一种矢量量化编码的快速匹配算法。利用码书的拓扑结构和柯西 施瓦兹不等式的性质推导出了消除不必要匹配操作的条件,并根据这个条件提出了快速搜索算法。实验结果表明,该算法不仅明显降低了矢量编码过程的复杂程度,同时也保证了与全搜索编码相同的图像编码质量。与其它搜索方法的操作次数和存储空间进行了比较。     

利用NMR谱仪及模拟机实现量子算法

报道了利用NMR谱仪和NMR模拟机实现量子算法.以天然苯为样品,我们分别用500 M谱仪和NMR模拟机实现了量子D-J算法,Grover搜寻算法及受控非门(C NOT).通过比较实验谱和模拟谱发现二者能很好符合.利用NMR模拟机实现量子算法比用NMR谱仪更为方便、清晰.     

Quantum Motion on 2D Surfaces of Spherical Topology

When the motion of a particle is constrained on the two-dimensional surface, excess terms exist in usual kinetic energy 1/(2μ) ∑ p _i ² with hermitian form of Cartesian momentum p _i (i = 1,2,3), and the operator ordering should be taken into account in the kinetic energy which turns out to be 1/(2μ) ∑ (1/f _i )p _i f _i p _i where the functions f _i are dummy factors in classical mechanics and nontrivial in quantum mechanics. In this article, the explicit forms of the dummy functions f _i for quantum motion on some 2D surfaces of revolution of spherical topology are given. PACS numbers: 03.65.-w Quantum mechanics, 04.60.Ds Canonical quantization.     

Universality of Operator Ordering in Kinetic Energy Operator for Particles Moving on two Dimensional Surfaces

When the motion of a particle is constrained on the two-dimensional surface, excess terms exist in usual kinetic energy 1/(2m)∑ p _i ² with hermitian form of Cartesian momentum p _i (i = 1,2,3), and the operator ordering should be taken into account in the kinetic energy which turns out to be 1/(2m)∑ (1/f _i )p _i f _i p _i where the functions f _i are dummy factors in classical mechanics and nontrivial in quantum mechanics. The existence of non-trivial f _i shows the universality of this constraint induced operator ordering in quantum kinetic energy operator for the constraint systems.