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Quantum algorithms and circuits can, in principle, outperform the best non-quantum (classical) techniques for some hard computational problems. However, this does not necessarily lead to useful applications. To gauge the practical…

Quantum Physics · Physics 2007-05-23 George F. Viamontes , Igor L. Markov , John P. Hayes

Classical optimization algorithms in machine learning often take a long time to compute when applied to a multi-dimensional problem and require a huge amount of CPU and GPU resource. Quantum parallelism has a potential to speed up machine…

Quantum Physics · Physics 2019-11-21 Venkat R. Dasari , Mee Seong Im , Lubjana Beshaj

Quantum Algorithms have long captured the imagination of computer scientists and physicists primarily because of the speed up achieved by them over their classical counterparts using principles of quantum mechanics. Entanglement is believed…

Quantum Physics · Physics 2013-05-31 Shantanav Chakraborty , Subhashish Banerjee , Satyabrata Adhikari , Atul Kumar

In a recent paper (quant-ph/0506105), A S Gupta, M. Gupta and A. Pathak proposed a modified Grover algorithm that would exponentially accelerate the unsorted database search problem if the number of marked items is known. If this were true,…

Quantum Physics · Physics 2007-05-23 Gui Lu Long

Recently, Farhi, Goldstone, and Gutmann gave a quantum algorithm for evaluating NAND trees that runs in time O(sqrt(N log N)) in the Hamiltonian query model. In this note, we point out that their algorithm can be converted into an algorithm…

Quantum Physics · Physics 2019-09-10 Andrew M. Childs , Richard Cleve , Stephen P. Jordan , David Yonge-Mallo

L. K. Grover's search algorithm in quantum computing gives an optimal, quadratic speedup in the search for a single object in a large unsorted database. In this paper, we generalize Grover's algorithm in a Hilbert-space framework for both…

Quantum Physics · Physics 2007-05-23 Goong Chen , Stephen A. Fulling , Jeesen Chen

Let $f$ denote length preserving function on words. A classical algorithm can be considered as $T$ iterated applications of black box representing $f$, beginning with input word $x$ of length $n$. It is proved that if $T=O(2^{n/(7+e)}), e…

Quantum Physics · Physics 2007-05-23 Yuri Ozhigov

The possibility to save and process information in fundamentally indistinguishable states is the quantum mechanical resource that is not encountered in classical computing. I demonstrate that, if energy constraints are imposed, this…

Quantum Physics · Physics 2018-02-14 N. A. Sinitsyn

Involving only the measurements of commuting observables - the problem-setting and the corresponding solution - quantum algorithms should be subject to classical logic. This would allow flanking their customary quantum description with a…

Quantum Physics · Physics 2025-07-08 Giuseppe Castagnoli

Withdrawn by the author due to irreparable errors. We present a quantum algorithm that in the black-box model performs a search in an ordered list of N elements. Using 3/4 log N + O(1) queries, it achieves a success probability of at least…

Quantum Physics · Physics 2007-05-23 Hein Roehrig

In the quantum database search problem we are required to search for an item in a database. In this paper, we consider a generalization of this problem, where we are provided d identical copes of a database each with N items which we can…

Quantum Physics · Physics 2007-05-23 Lov K. Grover , Jaikumar Radhakrishnan

Markov chain methods are remarkably successful in computational physics, machine learning, and combinatorial optimization. The cost of such methods often reduces to the mixing time, i.e., the time required to reach the steady state of the…

Quantum Physics · Physics 2018-11-15 Davide Orsucci , Hans J. Briegel , Vedran Dunjko

L. K. Grover's search algorithm in quantum computing gives an optimal, square-root speedup in the search for a single object in a large unsorted database. In this paper, we expound Grover's algorithm in a Hilbert-space framework that…

Quantum Physics · Physics 2007-05-23 G. Chen , S. A. Fulling , M. O. Scully

We investigate the quantum algorithms for dynamic programming by Ambainis et al. (SODA'19). While giving provable complexity speedups and applicable to a variety of NP-hard problems, these algorithms have a notable drawback: they require a…

Quantum Physics · Physics 2026-04-03 Susanna Caroppo , Jevgēnijs Vihrovs , Dārta Zajakina , Aleksejs Zajakins

Many recent investigations conclude, based on asymptotic complexity analyses, that quantum computers could accelerate combinatorial optimization (CO) tasks relative to a purely classical computer. However, asymptotic analysis alone cannot…

Quantum Physics · Physics 2024-12-18 Pedro C. S. Costa , Mauro E. S. Morales , Dong An , Yuval R. Sanders

We generalize Grover's unstructured quantum search algorithm to enable it to use an arbitrary starting superposition and an arbitrary unitary matrix simultaneously. We derive an exact formula for the probability of the generalized Grover's…

Quantum Physics · Physics 2008-12-18 Robert Gingrich , Colin P. Williams , Nicolas Cerf

Decoherence in quantum searches, and in the Grover search in particular, has already been extensively studied, leading very quickly to the loss of the quadratic speedup over the classical case, when searching for some target (marked)…

Quantum Physics · Physics 2019-01-29 D. Reitzner , M. Hillery

Machines are possible to have some artificial intelligence like human beings owing to particular algorithms or software. Such machines could learn knowledge from what people taught them and do works according to the knowledge. In practical…

Quantum Physics · Physics 2015-04-16 Li Zhaokai , Liu Xiaomei , Xu Nanyang , Du jiangfeng

Executing quantum circuits on currently available quantum computers requires compiling them to a representation that conforms to all restrictions imposed by the targeted architecture. Due to the limited connectivity of the devices' physical…

Quantum Physics · Physics 2023-01-11 Lukas Burgholzer , Sarah Schneider , Robert Wille

Quantum algorithms theoretically outperform classical algorithms in solving problems of increasing size, but computational errors must be kept to a minimum to realize this potential. Despite the development of increasingly capable quantum…

Quantum Physics · Physics 2023-12-22 Bibek Pokharel , Daniel A. Lidar