共查询到20条相似文献,搜索用时 31 毫秒
1.
《理论物理通讯》2017,(4)
In adiabatic quantum algorithm, the success rate is approximately equal to 1 while the run time satisfies the adiabatic condition. But the relation between the short run time and success rate for adiabatic quantum algorithm is poorly understood. In this paper, we study the success rate of local adiabatic quantum search algorithm with an arbitrary finite run time(non-adiabatic evolution). By solving the time-independent Schr¨odinger equation, we obtain differential equations to calculate the success rate. The differential equations show that the success rate is closely related to the adiabatic parameter s(t). Utilize the differential equations, we give the function of success rate versus run time in local adiabatic search numerically. The result indirectly verifies that T ~ O(N~(1/2)) is optimal in local adiabatic search. 相似文献
2.
Fu Xiangqun Bao Wansu Shi Jianhong Li Tan Wang Xiang 《International Journal of Theoretical Physics》2019,58(5):1534-1540
International Journal of Theoretical Physics - Problems which can be solved on classical computer in polynomial time may not be able to be solved on quantum computer. And a quantum algorithm will... 相似文献
3.
Hossein Mehri-Dehnavi Hasan Dashtianeh Hossein Yahyavi Kuchaksaraei Masumeh Mahmoodi Khoshdareh Hossein Movahhedian Robabeh Rahimi 《International Journal of Theoretical Physics》2018,57(12):3668-3681
We show that by adding a workspace qubit to Ahmed Younes, et al. algorithm (Younes et al. AIP Conf. Proc. 734:171, 2004, 2008), and applying newly defined partial diffusion operators on subsystems, the algorithm’s performance is improved. We consider an unstructured list of N items and M matches, 1 ≤ M ≤ N. 相似文献
4.
Yang Liu 《International Journal of Theoretical Physics》2014,53(8):2571-2578
In standard Grover’s algorithm for quantum searching, the probability of finding a marked state is not exactly 1, and some modified versions of Grover’s algorithm that search a marked state from an evenly distributed database with full successful rate have been presented. In this article, we present a generalized quantum search algorithm that searches M marked states from an arbitrary distributed N-item quantum database with a zero theoretical failure rate, where N is not necessary to be the power of 2. We analyze the general properties of our search algorithm, we find that our algorithm has periodicity with a period of 2J + 1, and it is effective with certainty for J + (2J + 1)m times of iteration, where m is an arbitrary nonnegative number. 相似文献
5.
Rigui Zhou Huian Wang Qian Wu Yang Shi 《International Journal of Theoretical Physics》2012,51(3):705-723
Based on analysis on properties of quantum linear superposition, to overcome the complexity of existing quantum associative
memory which was proposed by Ventura, a new storage method for multiply patterns is proposed in this paper by constructing
the quantum array with the binary decision diagrams. Also, the adoption of the nonlinear search algorithm increases the pattern
recalling speed of this model which has multiply patterns to O( log22n -t ) = O( n - t )O( {\log_{2}}^{2^{n -t}} ) = O( n - t ) time complexity, where n is the number of quantum bit and t is the quantum information of the t quantum bit. Results of case analysis show that the associative neural network model proposed in this paper based on quantum
learning is much better and optimized than other researchers’ counterparts both in terms of avoiding the additional qubits
or extraordinary initial operators, storing pattern and improving the recalling speed. 相似文献
6.
Wei-Wei Zhang Dan Li Ting-Ting Song Yan-Bing Li 《International Journal of Theoretical Physics》2013,52(5):1466-1473
We propose two quantum private comparison protocols based on quantum search algorithm with the help of a semi-honest third party. Our protocols utilize the properties of quantum search algorithm, the unitary operations, and the single-particle measurements. The security of our protocols is discussed with respect to both the outsider attack and the participant attack. There is no information leaked about the private information and the comparison result, even the third party cannot know these information. 相似文献
7.
Hsin-Yi Tseng Chia-Wei Tsai Tzonelih Hwang Chuan-Ming Li 《International Journal of Theoretical Physics》2012,51(10):3101-3108
Quantum secret sharing (QSS) and quantum search algorithm (QSA) are considered as two important but different research topics in quantum information science. This paper recognizes an important feature in the well-known Grover’s QSA and then applies it to propose a QSS protocol. In contrast to the existing QSA-based QSS protocols, the newly proposed protocol has the following two advantages: (1)?no quantum memory is required by the agents, whereas the agents in the existing QSA-based QSS protocols need long-term quantum memories to store their secret shadows; (2)?the agents can cooperate to recover the boss’s secret by using shadows in classical bits, whereas, the others have to combine their shadows in photons and perform a unitary operation on the retained photons. The proposed QSS protocol is also shown to be secure against eavesdroppers or malicious agents. 相似文献
8.
非绝热消除条件下输出边频量子关联 总被引:1,自引:0,他引:1
考虑了双模腔内含有N个三能级V型原子的系综与两个量子化场之间的相互作用。在非绝热消除原子变量的条件下,分析了两个初始为相干态的输入场从腔内输出后的量子关联性质。结果表明在恰当的条件下,在中心频率处可以获得量子纠缠,但随合作参数的增加,中心频率处的纠缠变小甚至消失。与此同时,在高频区间则产生了一对边频量子纠缠。这是由于合作参数增加引起的真空拉比分裂导致了高频处获得量子关联。此外,通过调节量子化场的强度以及原子和场的反对称失谐,还可获得两对边频量子纠缠。这对边频量子关联的研究具有十分重要的价值。 相似文献
9.
We propose a method of controlling the dc-SQUID (superconducting quantum interference device) systemby changing the gate voltages, which controls the amplitude of the fictitious magnetic fields Bz, and the externallyapplied current that produces the piercing magnetic fiux φx for the dc-SQUID system. We have also introduced aphysical model for the dc-SQUID system. Using this physical model, one can obtain the non-adiabatic geometric phasegate for the single qubit and the non-adiabatic conditional geometric phase gate (controlled NOT gate) for the twoqubits. It is shown that when the gate voltage and the externally applied current of the dc-SQUID system satisfies anappropriate constraint condition, the charge state evolution can be controlled exactly on a dynamic phase free path. Thenon-adiabatic evolution of the charge states is given as well. 相似文献
10.
The success probability of the Grover quantum search algorithm decreases quickly when the fraction of target items exceeds 1/4, where the phase plays a significant role. Therefore, we use multiple phases to complement each other. We obtain three useful properties and an important theorem of the success probability and design a systematic solution of the optimal phases for an arbitrary number of phases. Based on these results, we finally propose a multi-phase quantum search algorithm whose success probability rises with the increase of the number of phases with just a single iteration, and it tends to be 100% when the fraction of target items is over a lower limit. 相似文献
11.
Hsin-Yi Tseng Chia-Wei Tsai Tzonelih Hwang 《International Journal of Theoretical Physics》2012,51(8):2447-2454
In this study, we propose a controlled deterministic secure quantum communication (CDSQC) protocol based on the idea of Grover’s quantum search algorithm (QSA). The proposed protocol has the following two advantages over the existing CDSQC protocols: (1) high qubit frequency and (2) less quantum memory. Moreover, the security analysis of the proposed protocol shows that any eavesdropper will be detected with a very high probability under both ideal and noisy quantum channel conditions. 相似文献
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13.
Xin-Xin Jiang 《International Journal of Theoretical Physics》2013,52(10):3457-3461
We propose a simple scheme to implement the two-qubit Grover quantum search algorithm with trapped ions in thermal motion. In the scheme two states of the Λ-type three-level ions are used as quantum bits (qubits). The scheme puts no limitations on the intensity of the laser field and the speed of the hot ions, and all the operations can be achieved in a reasonable amount of time before decoherence sets in. The scheme might be experimentally realizable with presently available techniques. 相似文献
14.
一个量子系统将不可避免地受到不可预知的微扰影响,据此断定文献中的Grover量子搜索算法的实验实现是在三维复子空间中完成的.同时证明在二维复子空间中,对任意给定的初始态|γ0>=cosβ0| α>+sinβ0eiζ|β>(β0是较小的正实数,ζ是任意的一个实数),存在解集Fj={(θj,θj-1,…,θ1),(φj,φj-1,…,φ1)}(整数j≥2)使得目标态能以100%的最大成功概率找到,其中相位旋转角θj和φl是不为2k’π的实数(1≤l≤j,k’为任意整数).如果只要求目标态以较高的成功概率找到,那么当一个无序数据库中目标态和非目标态的总个数足够大时,对于相对较小的正整数j,解集Fj可表示为j∑l=1θl=j∑l=1φl的形式. 相似文献
15.
The quantum random walk is a possible approach to construct new quantum search algorithms. It has been shown by Shenvi et al. [Phys. Rev. A 67(2003)52307] that a kind of algorithm can perform an oracle search on a database of N items with O(√N) calling to the oracle, yielding a speedup similar to other quantum search algorithms. We study the effect of white or Gaussian noise on this algorithm. The algorithm loses efficiency when noise is added. We also show that noise on the target state plays a more important role than that on other states. Finally we compare the effects of similar types of noise in the quantum random walk search algorithm and Grover's search algorithm. 相似文献
16.
WANG Yan-Hui ZHANG Yong 《理论物理通讯》2008,49(6):1487-1490
Using cluster state and single qubit measurement one can perform the one-way quantum computation. Here we give a detailed scheme for realizing a modified Grover search algorithm using measurements on cluster state. We give the measurement pattern for the cluster-state realization of the algorithm and estimated the number of measurement needed for its implementation. It is found that O(2^3n/^2n^2) number of single qubit measurements is required for its realization in a cluster-state quantum computer. 相似文献
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18.
The nonadiabatic entropy production is a useful tool for the thermodynamic analysis of continuously dissipating, nonequilibrium steady states. For open quantum systems, two seemingly distinct definitions for the nonadiabatic entropy production have appeared in the literature, one based on the quantum relative entropy and the other based on quantum trajectories. We show that these two formulations are equivalent. Furthermore, this equivalence leads us to a proof of the monotonicity of the quantum relative entropy under a special class of completely-positive, trace-preserving quantum maps, which circumvents difficulties associated with the noncommuntative structure of operators. 相似文献
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20.
Ri-Gui Zhou Chen-Yi Shen Tian-ru Xiao Yan-cheng Li 《International Journal of Theoretical Physics》2013,52(11):3970-3980
This paper we proposed a quantum pattern search algorithm based on Grover’s algorithm with closed match. Compared to QuAM proposed by Dan Ventura and QuAM with distributed queries proposed by Ezhov, our algorithm could not only resolve completion problem but also retrieved the full information of the query pattern which only known partial information with non-negligible probability. The algorithm took advantage of the encoding for the pattern set. Moreover we transformed the encoding of each pattern in set to encode all the pattern match cases in order to reduce the cost of encoding. Thus, the nontrivial initial state brought a new method to realize quantum pattern search with a series of proper unitary operations. The simulation result of experiments was also proved that our algorithm was useful and efficient. 相似文献