Similar to the classical meet-in-the-middle algorithm, the storage and computation complexity are the key factors that decide the efficiency of the quantum meet-in-the-middle algorithm. Aiming at the target vector of ...
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Similar to the classical meet-in-the-middle algorithm, the storage and computation complexity are the key factors that decide the efficiency of the quantum meet-in-the-middle algorithm. Aiming at the target vector of fixed weight, based on the quantum meet-in-the-middle algorithm, the algorithm for searching all n-product vectors with the same weight is presented, whose complexity is better than the exhaustive searchalgorithm. And the algorithm can reduce the storage complexity of the quantum meet-in-the-middle searchalgorithm. Then based on the algorithm and the knapsack vector of the Chor-Rivest public-key crypto of fixed weight d, we present a general quantum meet-in-the-middle searchalgorithm based on the target solution of fixed weight, whose computational complexity is Sigma(d)(j=0) (O (\/C-n-k+1(d-j) + O(C-k(j) log C-k(j)) with Sigma(d)(i=0) C-k(i) memory cost. And the optimal value of k is given. Compared to the quantum meet-in-the-middle searchalgorithm for knapsack problem and the quantumalgorithm for searching a target solution of fixed weight, the computational complexity of the algorithm is lower. And its storage complexity is smaller than the quantum meet-in-the-middle-algorithm.
Despite the advent of Grover's algorithm for the unstructured search, its successful implementation on near-term quantum devices is still limited. We apply three strategies to reduce the errors associated with imp...
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Despite the advent of Grover's algorithm for the unstructured search, its successful implementation on near-term quantum devices is still limited. We apply three strategies to reduce the errors associated with implementing quantum search algorithms. Our improved searchalgorithms have been implemented on the IBM quantum processors. Using them, we demonstrate three- and four-qubit searchalgorithm with higher average success probabilities compared to previous works. We present the successful execution of the five-qubit search on the IBM quantum processor for the first time. The results have been benchmarked using degraded ratio, which is the ratio between the experimental and the theoretical success probabilities. The fast decay of the degraded ratio supports our divide-and-conquer strategy. Our proposed strategies are also useful for implementation of quantum search algorithms in the post-NISQ era.
Since Grover's seminal work which provides a way to speed up combinatorial search, quantumsearch has been studied in great detail. We propose a new method for designing quantum search algorithms for finding a mar...
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Since Grover's seminal work which provides a way to speed up combinatorial search, quantumsearch has been studied in great detail. We propose a new method for designing quantum search algorithms for finding a marked element in the state space of a graph. The algorithm is based on a local adiabatic evolution of the Hamiltonian associated with the graph. The main new idea is to apply some techniques such as Krylov subspace projection methods, Lanczos algorithm and spectral distribution methods. Indeed, using these techniques together with the second-order perturbation theory, we give a systematic method for calculating the approximate search time at which the marked state can be reached. That is, for any undirected regular connected graph which is considered as the state space of the database, the introduced algorithm provides a systematic and programmable way for evaluation of the search time, in terms of the corresponding graph polynomials.
Studies have demonstrated that a joined complete graph is a typical mathematical model that can support a fast quantumsearch. In this paper, we study the implementation of joined complete graphs in atomic systems and...
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Studies have demonstrated that a joined complete graph is a typical mathematical model that can support a fast quantumsearch. In this paper, we study the implementation of joined complete graphs in atomic systems and realize a quantumsearch of runtime ■ based on this implementation with a success probability of 50%. Even though the practical systems inevitably interact with the surrounding environment, we reveal that a successful quantumsearch can be realized through delicately engineering the environment itself. We consider that our study will bring about a feasible way to realize quantum information processing including quantumalgorithms in reality.
With the explosive proliferation of mobile devices, the scarcity of communication resources has emerged as a critical issue in the next generation (NG) communication systems. To overcome this, non-orthogonal multiple ...
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With the explosive proliferation of mobile devices, the scarcity of communication resources has emerged as a critical issue in the next generation (NG) communication systems. To overcome this, non-orthogonal multiple access (NOMA) has been shown to provide a beneficial spectral effi ciency gain, while supporting massive connectivity. Sparse code multiple access (SCMA) is one of the NOMA schemes, but its application is hampered by its high-complexity multi-user detection. Fortunately, quantumsearch techniques were shown to substantially reduce the complexity of multi-user detectors (MUD). However, the quantumsearch-aided multiuser detection of SCMA is an open problem at the time of writing. Hence, we conceive a pair of quantumsearch-aided MUDs for SCMA, namely, a quantum-assisted message passing algorithm (Q-MPA)-based MUD and a quantum-assisted sphere decoder-based MPA (QSD-MPA) MUD.
In this work, we consider a family of sure-success quantumalgorithms, which is grouped into even and odd members for solving a generalized Grover search problem. We prove the matching conditions for both groups and g...
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In this work, we consider a family of sure-success quantumalgorithms, which is grouped into even and odd members for solving a generalized Grover search problem. We prove the matching conditions for both groups and give the corresponding formulae for evaluating the iterations or oracle calls required in the search computation. We also present how to adjust the phase angles in the generalized Grover operator to ensure the sure-success if minimal oracle calls axe demanded in the search.
In this article,we review quantum search algorithms for unsorted database search *** database search is a very important problem in science and *** a quantum computer,a marked state can be found with very high probabi...
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In this article,we review quantum search algorithms for unsorted database search *** database search is a very important problem in science and *** a quantum computer,a marked state can be found with very high probability using the Grover's algorithm,or exactly with the Long *** review the Grover algorithm and related *** particular,we review the phase matching conditions in quantumsearch *** issues that may cause confusion about the quantum search algorithm are also clarified.
We consider the problem of finding one or more desired items out of an unsorted database. Patel has shown that if the database permits quantum queries, then mere digitization is sufficient for efficient search for one...
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We consider the problem of finding one or more desired items out of an unsorted database. Patel has shown that if the database permits quantum queries, then mere digitization is sufficient for efficient search for one desired item. The algorithm, called factorized quantum search algorithm, presented by him can locate the desired item in an unsorted database using O() queries to factorized oracles. But the algorithm requires that all the attribute values must be distinct from each other. In this paper, we discuss how to make a database satisfy the requirements, and present a quantumsearch engine based on the algorithm. Our goal is achieved by introducing auxiliary files for the attribute values that are not distinct, and converting every complex query request into a sequence of calls to factorized quantum search algorithm. The query complexity of our algorithm is O() for most cases.
For searching any item in an unsorted database with N items, a classical computer takes O(N) steps but Grover's quantumsearching algorithm takes only O(root N) steps. However, it is also known that Grover's a...
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ISBN:
(纸本)9789881925114
For searching any item in an unsorted database with N items, a classical computer takes O(N) steps but Grover's quantumsearching algorithm takes only O(root N) steps. However, it is also known that Grover's algorithm is effective only in the case where the initial amplitude distribution of dataset is uniform, but is not always effective in the non-uniform case. In this paper, we propose some quantum search algorithms. First, we propose an algorithm in analog time based on quantum walk by solving the schrodinger equation. The proposed algorithm shows best performance in optimum time. Next, we will apply the result to Grover searchalgorithm. It is shown that the proposed algorithm shows better performance than the conventional one. Further, we propose the improved algorithm by introducing the idea of the phase rotation. The algorithm shows best performance compared with the conventional ones.
Among many classic heuristic searchalgorithms, the Grover quantum search algorithm (QSA) can play a role of secondary acceleration. Based on the properties of the two-qubit Grover QSA, a quantum dialogue (QD) protoco...
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Among many classic heuristic searchalgorithms, the Grover quantum search algorithm (QSA) can play a role of secondary acceleration. Based on the properties of the two-qubit Grover QSA, a quantum dialogue (QD) protocol is proposed. In addition, our protocol also utilizes the unitary operations and single-particle measurements. The transmitted quantum state (except for the decoy state used for detection) can transmit two-bits of security information simultaneously. Theoretical analysis shows that the proposed protocol has high security.
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