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Quantum walk has been successfully used to search for targets on graphs with vertices identified as the elements of a database. This spacial search on a two-dimensional periodic grid takes $\mathcal{O}\left(\sqrt{N\log N}\right)$ oracle…

Quantum Physics · Physics 2025-03-07 Pulak Ranjan Giri

Quantum algorithms are able to solve particular problems exponentially faster than conventional algorithms, when implemented on a quantum computer. However, all demonstrations to date have required already knowing the answer to construct…

Quantum Physics · Physics 2013-03-22 Xiao-Qi Zhou , Pruet Kalasuwan , Timothy C. Ralph , Jeremy L. O'Brien

We investigate the generalisation of quantum search of unstructured and totally ordered sets to search of partially ordered sets (posets). Two models for poset search are considered. In both models, we show that quantum algorithms can…

Quantum Physics · Physics 2009-06-18 Ashley Montanaro

An unstructured search for one item out of N can be performed quantum mechanically in time of order square root of N whereas classically this requires of order N steps. This raises the question of whether square root speedup persists in…

Quantum Physics · Physics 2007-05-23 Edward Farhi , Sam Gutmann

Link prediction methods use patterns in known network data to infer which connections may be missing. Previous work has shown that continuous-time quantum walks can be used to represent path-based link prediction, which we further study…

Quantum Physics · Physics 2022-12-01 João P. Moutinho , Duarte Magano , Bruno Coutinho

Quantum algorithms require less operations than classical algorithms. The exact reason of this has not been pinpointed until now. Our explanation is that quantum algorithms know in advance 50% of the solution of the problem they will find…

Quantum Physics · Physics 2015-05-13 Giuseppe Castagnoli

With reference to a search in a database of size N, Grover states: "What is the reason that one would expect that a quantum mechanical scheme could accomplish the search in O(square root of N) steps? It would be insightful to have a simple…

Quantum Physics · Physics 2009-11-13 Giuseppe Castagnoli

Variational quantum algorithms (VQAs) are prominent candidates for near-term quantum advantage but lack rigorous guarantees of convergence and generalization. By contrast, quantum phase estimation (QPE) provides provable performance under…

Quantum Physics · Physics 2025-10-09 Tuyen Nguyen , Mária Kieferová

We present quantum algorithms for the following graph problems: finding a maximal bipartite matching in time O(n sqrt{m+n} log n), finding a maximal non-bipartite matching in time O(n^2 (sqrt{m/n} + log n) log n), and finding a maximal flow…

Quantum Physics · Physics 2007-05-23 Andris Ambainis , Robert Spalek

We introduce a quantum dynamic programming framework that allows us to directly extend to the quantum realm a large body of classical dynamic programming algorithms. The corresponding quantum dynamic programming algorithms retain the same…

Quantum algorithm is constructed which verifies the formulas of predicate calculus in time $O(\sqrt N)$ with bounded error probability, where $N$ is the time required for classical algorithms. This algorithm uses the polynomial number of…

Quantum Physics · Physics 2007-05-23 Yuri Ozhigov

Solving linear systems of equations is a common problem that arises both on its own and as a subroutine in more complex problems: given a matrix A and a vector b, find a vector x such that Ax=b. We consider the case where one doesn't need…

Quantum Physics · Physics 2009-10-08 Aram W. Harrow , Avinatan Hassidim , Seth Lloyd

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

In former work, we showed that a quantum algorithm requires the number of operations (oracle's queries) of a classical algorithm that knows in advance 50% of the information that specifies the solution of the problem. We gave a preliminary…

Quantum Physics · Physics 2010-04-07 Giuseppe Castagnoli

An important family of span programs, st-connectivity span programs, have been used to design quantum algorithms in various contexts, including a number of graph problems and formula evaluation problems. The complexity of the resulting…

Quantum Physics · Physics 2018-11-05 Michael Jarret , Stacey Jeffery , Shelby Kimmel , Alvaro Piedrafita

We present three new quantum algorithms in the quantum query model for \textsc{graph-collision} problem: \begin{itemize} \item an algorithm based on tree decomposition that uses $O\left(\sqrt{n}t^{\sfrac{1}{6}}\right)$ queries where $t$ is…

Quantum Physics · Physics 2013-05-07 Andris Ambainis , Kaspars Balodis , Jānis Iraids , Raitis Ozols , Juris Smotrovs

Quantum search is a technique for searching N possibilities in only O(sqrt(N)) steps. It has been applied in the design of quantum algorithms for several structured problems. Many of these algorithms require significant amount of quantum…

Quantum Physics · Physics 2007-05-23 Lov Grover , Terry Rudolph

Utilising quantum computing technology to enhance artificial intelligence systems is expected to improve training and inference times, increase robustness against noise and adversarial attacks, and reduce the number of parameters without…

Software Engineering · Computer Science 2024-12-18 Mykhailo Klymenko , Thong Hoang , Xiwei Xu , Zhenchang Xing , Muhammad Usman , Qinghua Lu , Liming Zhu

Quantum algorithms have the potential to provide exponential speedups over some of the best known classical algorithms. These speedups may enable quantum devices to solve currently intractable problems such as those in the fields of…

Quantum Physics · Physics 2018-12-13 Ciarán Ryan-Anderson

Quantum algorithms can be analyzed in a query model to compute Boolean functions where input is given in a black box, but the aim is to compute function value for arbitrary input using as few queries as possible. In this paper we…

Quantum Physics · Physics 2012-03-24 Alina Dubrovska Vasilieva , Taisia Mischenko-Slatenkova