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One of the significant breakthroughs in quantum computation is Grover's algorithm for unsorted database search. Recently, the applications of Grover's algorithm to solve global optimization problems have been demonstrated, where unknown…

Quantum Physics · Physics 2017-11-22 Yan Wang

Lackadaisical quantum walk(LQW) has been an efficient technique in searching a target state from a database which is distributed on a two-dimensional lattice. We numerically study the quantum search algorithm based on the lackadaisical…

Quantum Physics · Physics 2019-12-04 Pulak Ranjan Giri , Vladimir Korepin

In this work we study quantum algorithms for Hopcroft's problem which is a fundamental problem in computational geometry. Given $n$ points and $n$ lines in the plane, the task is to determine whether there is a point-line incidence. The…

Quantum Physics · Physics 2024-05-03 Vladimirs Andrejevs , Aleksandrs Belovs , Jevgēnijs Vihrovs

This comment is to correct the proof of optimality of quantum spatial search for Erd\H{o}s-R\'enyi graphs presented in `Spatial Search by Quantum Walk is Optimal for Almost all Graphs' (https://doi.org/10.1103/PhysRevLett.116.100501). The…

Quantum Physics · Physics 2020-09-29 Ryszard Kukulski , Adam Glos

Quantum searching for one of $N$ marked items in an unsorted database of $n$ items is solved in $\mathcal{O}(\sqrt{n/N})$ steps using Grover's algorithm. Using nonlinear quantum dynamics with a Gross-Pitaevskii type quadratic nonlinearity,…

Quantum Physics · Physics 2017-12-12 K. de Lacy , L. Noakes

One approach to the development of quantum search algorithms is the quantum walk. A spatial search can be effected by the continuous-time evolution of a single quantum particle on a graph containing a marked site. In many physical…

Quantum Gases · Physics 2013-12-10 Mahdi Ebrahimi Kahou , David L. Feder

This paper describes a quantum algorithm for finding the maximum among N items. The classical method for the same problem takes O(N) steps because we need to compare two numbers in one step. This algorithm takes O(sqrt(N)) steps by…

Quantum Physics · Physics 2007-05-23 Ashish Ahuja , Sanjiv Kapoor

Quantum versions of random walks on the line and the cycle show a quadratic improvement over classical random walks in their spreading rates and mixing times respectively. Non-unitary quantum walks can provide a useful optimisation of these…

Quantum Physics · Physics 2008-03-25 Viv Kendon , Olivier Maloyer

The quantum SearchRank algorithm is a promising tool for a future quantum search engine based on PageRank quantization. However, this algorithm loses its functionality when the $N/M$ ratio between the network size $N$ and the number of…

Quantum Physics · Physics 2024-10-22 Sergio A. Ortega , Miguel A. Martin-Delgado

We propose a novel quantum algorithm for solving linear optimization problems by quantum-mechanical simulation of the central path. While interior point methods follow the central path with an iterative algorithm that works with successive…

Quantum Physics · Physics 2024-10-17 Brandon Augustino , Jiaqi Leng , Giacomo Nannicini , Tamás Terlaky , Xiaodi Wu

There has been a very large body of research on searching a marked vertex on a graph based on quantum walks, and Grover's algorithm can be regarded as a quantum walk-based search algorithm on a special graph. However, the existing quantum…

Quantum Physics · Physics 2022-11-22 Yongzhen Xu , Delong Zhang , Lvzhou Li

We prove that any exact quantum algorithm searching an ordered list of N elements requires more than \frac{1}{\pi}(\ln(N)-1) queries to the list. This improves upon the previously best known lower bound of {1/12}\log_2(N) - O(1). Our proof…

Quantum Physics · Physics 2007-05-23 Peter Hoyer , Jan Neerbek

This paper researches how the systematic errors in phase inversions affect the success rate and the number of iterations in optimized quantum random-walk search algorithm. Through geometric description of this algorithm, the model of the…

Quantum Physics · Physics 2015-01-12 Yu-Chao Zhang , Wan-Su Bao , Xiang Wang , Xiang-Qun Fu

We present an extension to the quantum walk search framework that facilitates quantum walks with nested updates. We apply it to give a quantum walk algorithm for 3-Distinctness with query complexity ~O(n^{5/7}), matching the best known…

Quantum Physics · Physics 2013-03-01 Andrew M. Childs , Stacey Jeffery , Robin Kothari , Frederic Magniez

We analyze the realization of a quantum-walk search algorithm in a passive, linear optical network. The specific model enables us to consider the effect of realistic sources of noise and losses on the search efficiency. Photon loss uniform…

Quantum Physics · Physics 2008-02-04 A. Gabris , T. Kiss , I. Jex

Efficient and coherent data retrieval and storage are essential for harnessing quantum algorithms' speedup. Such a fundamental task is addressed by a quantum Random Access Memory (qRAM). Despite their promising scaling properties, current…

Quantum Physics · Physics 2026-04-09 Giuseppe De Riso , Giuseppe Catalano , Seth Lloyd , Vittorio Giovannetti , Dario De Santis

We consider the following distributed pursuit-evasion problem. A team of mobile agents called searchers starts at an arbitrary node of an unknown $n$-node network. Their goal is to execute a search strategy that guarantees capturing a fast…

Discrete Mathematics · Computer Science 2021-01-19 Dariusz Dereniowski , Dorota Urbańska

We study variable time search, a form of quantum search where queries to different items take different time. Our first result is a new quantum algorithm that performs variable time search with complexity $O(\sqrt{T}\log n)$ where…

Quantum Physics · Physics 2023-08-04 Andris Ambainis , Martins Kokainis , Jevgēnijs Vihrovs

Quantum search on the two-dimensional lattice with one marked vertex and cyclic boundary conditions is an important problem in the context of quantum algorithms with an interesting unfolding. It avails to test the ability of quantum walk…

Quantum Physics · Physics 2017-05-03 Renato Portugal , Tharso D. Fernandes

Kronecker graphs, obtained by repeatedly performing the Kronecker product of the adjacency matrix of an "initiator" graph with itself, have risen in popularity in network science due to their ability to generate complex networks with…

Quantum Physics · Physics 2018-08-01 Thomas G. Wong , Konstantin Wünscher , Joshua Lockhart , Simone Severini
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