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In this paper, we consider a continuous-time quantum walk based search algorithm. We introduce equitable partition of the graph and perfect state transfer on it. By these two methods, we can calculate the success probability and the finding…

Quantum Physics · Physics 2022-09-19 Yusuke Ide , Akihiro Narimatsu

We give a quantum algorithm for finding a marked element on the grid when there are multiple marked elements. Our algorithm uses quadratically fewer steps than a random walk on the grid, ignoring logarithmic factors. This is the first known…

Quantum Physics · Physics 2017-07-04 Peter Hoyer , Mojtaba Komeili

Quantum random walks on graphs have been shown to display many interesting properties, including exponentially fast hitting times when compared with their classical counterparts. However, it is still unclear how to use these novel…

Quantum Physics · Physics 2009-11-07 Neil Shenvi , Julia Kempe , K. Birgitta Whaley

Quantum walk is fundamental to designing many quantum algorithms. Here we consider the effects of quantum coherence and quantum entanglement for the quantum walk search on the complete bipartite graph. First, we numerically show the…

Quantum Physics · Physics 2023-10-03 Meng Li , Xian Shi

We study the discrete-time quantum walk-based search for a marked vertex on a graph. By considering various structures in which not all vertices are equivalent, we investigate the relationship between the successful search probability and…

Quantum Physics · Physics 2015-03-17 Scott D. Berry , Jingbo B. Wang

Shenvi, Kempe and Whaley's quantum random-walk search (SKW) algorithm [Phys. Rev. A 67, 052307 (2003)] is known to require $O(\sqrt N)$ number of oracle queries to find the marked element, where $N$ is the size of the search space. The…

Quantum Physics · Physics 2009-03-20 V. Potocek , A. Gabris , T. Kiss , I. Jex

We introduce quantized bipartite walks, compute their spectra, generalize the algorithms of Grover \cite{g} and Ambainis \cite{amb03} and interpret them as quantum walks with memory. We compare the performance of walk based classical and…

Quantum Physics · Physics 2007-05-23 Mario Szegedy

We study scattering quantum walks on highly symmetric graphs and use the walks to solve search problems on these graphs. The particle making the walk resides on the edges of the graph, and at each time step scatters at the vertices. All of…

Quantum Physics · Physics 2009-01-27 Daniel Reitzner , Mark Hillery , Edgar Feldman , Vladimir Buzek

In a recent work by Novo et al. (Sci. Rep. 5, 13304, 2015), the invariant subspace method was applied to the study of continuous-time quantum walk (CTQW). The method helps to reduce a graph into a simpler version that allows more…

Quantum Physics · Physics 2018-02-22 Chen-Fu Chiang , Chang-Yu Hsieh

Spatial search is the problem of finding a marked vertex in a graph. A continuous-time quantum walk in the single-excitation subspace of an $n$ spin system solves the problem of spatial search by finding the marked vertex in $O(\sqrt{n})$…

Quantum Physics · Physics 2024-10-10 Dylan Lewis , Leonardo Banchi , Sougato Bose

We contribute to fulfil the long-lasting gap in the understanding of the spatial search with multiple marked vertices. The theoretical framework is that of discrete-time quantum walks (QW), \textit{i.e.} local unitary matrices that drive…

Quantum Physics · Physics 2023-01-06 Mathieu Roget , Hachem Kadri , Giuseppe Di Molfetta

The Maximum Matching problem has a quantum query complexity lower bound of $\Omega(n^{3/2})$ for graphs on $n$ vertices represented by an adjacency matrix. The current best quantum algorithm has the query complexity $O(n^{7/4})$, which is…

Quantum Physics · Physics 2025-10-31 Alcides Gomes Andrade Júnior , Akira Matsubayashi

Quantum walks have been very successful in the development of search algorithms in quantum information, in particular in the development of spatial search algorithms. However, the construction of continuous-time quantum search algorithms in…

Quantum Physics · Physics 2015-07-02 Iain Foulger , Sven Gnutzmann , Gregor Tanner

Quantum walks play an important role in the area of quantum algorithms. Many interesting problems can be reduced to searching marked states in a quantum Markov chain. In this context, the notion of quantum hitting time is very important,…

Quantum Physics · Physics 2009-12-08 R. A. M. Santos , R. Portugal

The quantum walk dynamics obey the laws of quantum mechanics with an extra locality constraint, which demands that the evolution operator is local in the sense that the walker must visit the neighboring locations before endeavoring to…

Quantum Physics · Physics 2023-05-23 Caue F. T. Silva , Daniel Posner , Renato Portugal

Continuous-time quantum walks are typically effected by either the discrete Laplacian or the adjacency matrix. In this paper, we explore a third option: the signless Laplacian, which has applications in algebraic graph theory and may arise…

Quantum Physics · Physics 2025-03-26 Molly E. McLaughlin , Thomas G. Wong

To investigate the performance of quantum information tasks on networks whose topology changes in time, we study the spatial search algorithm by continuous time quantum walk to find a marked node on a random temporal network. We consider a…

Quantum Physics · Physics 2017-11-30 Shantanav Chakraborty , Leonardo Novo , Serena Di Giorgio , Yasser Omar

In the typical model, a discrete-time coined quantum walk searching the 2D grid for a marked vertex achieves a success probability of $O(1/\log N)$ in $O(\sqrt{N \log N})$ steps, which with amplitude amplification yields an overall runtime…

Quantum Physics · Physics 2018-02-15 Thomas G. Wong

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

The running time of a quantum walk search algorithm depends on both the structure of the search space (graph) and the configuration of marked locations. While the first dependence have been studied in a number of papers, the second…

Quantum Physics · Physics 2015-07-15 Nikolajs Nahimovs , Alexander Rivosh