量子有哪些信誉好的足球投注网站算法中的相位匹配理论与NMR试验.PPT

Department of Physics, Tsinghua University Beijing, P R China Key Laboratory for Quantum Information and Measurements, Key Lab of MOE Collaborators From Tsinghua University Ph. D. Students Y S Li(李岩松) H Y Yan(阎海洋) L Xiao(肖丽)，F.G. Deng(邓富国） M.Sc. Students C C Tu(屠长存), X S Liu(刘晓曙) W L Zhang(张伟林)，H. Guo, Y. J. Ma From University of Tennessee Prof. Dr. Yang Sun(孙扬) 4. A Sample 1 2 3 4 x1 x2 x3 x4 4 edge Boolean variables: x1,x2,x3,x4 4 vertex Clauses: C1={x1,x4}, C2={x1,x2} C3={x2,x3}, C4={x3,x4} (1) can be written as : (x1+x4)(x1+x2)(x2+x3)(x3+x4)=1 (2) Using the rules of Boolean algebra we can get x1x3+x2x4=1 (3) We can use (3) as a query function of Grover’s searching algorithm. We construct the unitary gates series as following: x1 x3 x2 x4 0 0 0 Query value bit We can find that (1,1,1,1), (1,0,1,0), (1,1,1,0), (0,1,1,1), (0,1,0,1), (1,1,0,1), (1,0,1,1) are appropriate truth assignments. Checking them with the features of Hamilton circuit, we will find that only (1,1,1,1) is a Hamilton circuit. 3. The optimality theorem Grover’s algorithm is the fastest search algorithm for a quantum computer. Bennett, 1998(?) C. Zalka, Phys. Rev. A60 (1999) 2746 There have been efforts to build an exponentially fast quantum search algorithm: Chen and Diao, exponentially fast quantum search algorithm, quant-ph/0011109 Chen-Diao algorithm Suppose N=22n, the query is Define auxiliary query 1st j bits 0,excluding 0..0 Starting from For simplicity we assume the 1st bit of the marked state is not 0. Starting from the evenly distributed state, after n iteration, the marked state will be found exactly The algorithm seems exponentially fast. It is not exponentially fast, because the inversion about state |Sk has to be done with many queries. It contains no query. Contains one query. It takes two queries. Together with the query in I1, the total number of query