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We present a Hamiltonian quantum computation scheme universal for quantum computation (BQP). Our Hamiltonian is a sum of a polynomial number (in the number of gates L in the quantum circuit) of time-independent, constant-norm, 2-local…

Quantum Physics · Physics 2013-05-30 Daniel Nagaj

Discrete time quantum walks are known to be universal for quantum computation. This has been proven by showing that they can simulate a universal quantum gate set. In this paper, we examine computation by quantum walks in terms of language…

Formal Languages and Automata Theory · Computer Science 2014-08-04 Katie Barr , Viv Kendon

We investigate quantum walks in multiple dimensions with different quantum coins. We augment the model by assuming that at each step the amplitudes of the coin state are multiplied by random phases. This model enables us to study in detail…

Quantum Physics · Physics 2009-11-13 Jozef Kosik , Vladimir Buzek , Mark Hillery

It was recently shown that continuous-time quantum walks on dynamic graphs, i.e., sequences of static graphs whose edges change at specific times, can implement a universal set of quantum gates. This result treated all isolated vertices as…

Quantum Physics · Physics 2019-12-25 Thomas G. Wong

Quantum walk (QW) is the quantum analog of the random walk. QW is an integral part of the development of numerous quantum algorithms. Hence, an in-depth understanding of QW helps us to grasp the quantum algorithms. We revisit the…

Quantum Physics · Physics 2021-02-16 Mahesh N. Jayakody , Chandrakala Meena , Priodyuti Pradhan

Quantum counting is a key quantum algorithm that aims to determine the number of marked elements in a database. This algorithm is based on the quantum phase estimation algorithm and uses the evolution operator of Grover's algorithm because…

Quantum Physics · Physics 2023-12-11 Gustavo A. Bezerra , Raqueline A. M. Santos , Renato Portugal

Quantum walks, in virtue of the coherent superposition and quantum interference, possess exponential superiority over its classical counterpart in applications of quantum searching and quantum simulation. The quantum enhanced power is…

Quantum walks, both discrete (coined) and continuous time, form the basis of several quantum algorithms and have been used to model processes such as transport in spin chains and quantum chemistry. The enhanced spreading and mixing…

Quantum Physics · Physics 2010-12-10 Godfrey Leung , Paul Knott , Joe Bailey , Viv Kendon

A new approach to quantum walks is presented. Considering a quantum system undergoing some unitary discrete-time evolution in a directed graph G, we think of the vertices of G as sites that are occupied by the quantum system, whose internal…

Quantum Physics · Physics 2015-06-09 Chaobin Liu

Quantum walks (QWs) are of interest as examples of uniquely quantum behavior and are applicable in a variety of quantum search and simulation models. Implementing QWs on quantum devices is useful from both points of view. We describe a…

Quantum Physics · Physics 2020-09-08 Asif Shakeel

Hitting times are the average time it takes a walk to reach a given final vertex from a given starting vertex. The hitting time for a classical random walk on a connected graph will always be finite. We show that, by contrast, quantum walks…

Quantum Physics · Physics 2009-11-13 Hari Krovi , Todd A. Brun

Quantum walks have been shown to have a wide range of applications, from artificial intelligence, to photosynthesis, and quantum transport. Quantum stochastic walks (QSWs) generalize this concept to additional non-unitary evolution. In this…

Quantum Physics · Physics 2021-05-26 Peter K. Schuhmacher , Luke C. G. Govia , Bruno G. Taketani , Frank K. Wilhelm

Quantum gates are the building blocks of quantum circuits, which in turn are the cornerstones of quantum information processing. In this work, we theoretically investigate a single-step implementation of both a universal two- (CNOT) and…

Quantum Physics · Physics 2024-07-01 Luiz O. R. Solak , Daniel Z. Rossatto , Celso J. Villas-Boas

Quantum walks have emerged as an interesting approach to quantum information processing, exhibiting many unique properties compared to the analogous classical random walk. Here we introduce a model for a discrete-time quantum walk with…

Quantum Physics · Physics 2013-05-08 Peter P. Rohde , Gavin K. Brennen , Alexei Gilchrist

Continuous-time quantum walks and adiabatic quantum evolution are two general techniques for quantum computing, both of which are described by Hamiltonians that govern their evolutions by Schr\"odinger's equation. In the former, the…

Quantum Physics · Physics 2016-06-14 Thomas G. Wong , David A. Meyer

In this article, we propose a quantum communication protocol via 2-step discrete time quantum walks with two coins on a graph of 10 vertices containing both cycles and paths. Quantum walks are known for their ability to integrate quantum…

Quantum Physics · Physics 2025-01-22 Rachana Soni , Neelam Choudhary , Navneet Pratap Singh

Inspired by the classical phenomenon of random walk, the concept of quantum walk has emerged recently as a powerful platform for the dynamical simulation of complex quantum systems, entanglement production and universal quantum computation.…

Universal quantum computation may be realized based on quantum walk, by formulating it as a scattering problem on a graph. In this paper, we simulate quantum gates through electric circuits, following a recent report that a one-dimensional…

Mesoscale and Nanoscale Physics · Physics 2020-06-15 Motohiko Ezawa

Quantum walks are the quantum mechanical analogue of classical random walks and an extremely powerful tool in quantum simulations, quantum search algorithms, and even for universal quantum computing. In our work, we have designed and…

Quantum walks are a promising framework for developing quantum algorithms and quantum simulations. They represent an important test case for the application of quantum computers. Here we present different forms of discrete-time quantum…