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Graph neural networks (GNNs) have been widely used in graph-related contexts. It is known that the separation power of GNNs is equivalent to that of the Weisfeiler-Lehman (WL) test; hence, GNNs are imperfect at identifying all…

Machine Learning · Computer Science 2025-02-07 Ziang Chen , Qiao Zhang , Runzhong Wang

In the theory of quantum information, the mixed-unitary quantum channels, for any positive integer dimension $n$, are those linear maps that can be expressed as a convex combination of conjugations by $n\times n$ complex unitary matrices.…

Quantum Physics · Physics 2022-07-19 Mark Girard , Debbie Leung , Jeremy Levick , Chi-Kwong Li , Vern Paulsen , Yiu Tung Poon , John Watrous

We analyze continuous-time quantum and classical random walk on spidernet lattices. In the framework of Stieltjes transform, we obtain density of states, which is an efficiency measure for the performance of classical and quantum mechanical…

Quantum Physics · Physics 2010-04-06 S. Salimi

A discrete-time quantum walk is the quantum analogue of a Markov chain on a graph. Zhan [J. Algebraic Combin. 53(4):1187-1213, 2020] proposes a model of discrete-time quantum walk whose transition matrix is given by two reflections, using…

Combinatorics · Mathematics 2022-11-24 Krystal Guo , Vincent Schmeits

Quantum walks provide a natural framework to approach graph problems with quantum computers, exhibiting speedups over their classical counterparts for tasks such as the search for marked nodes or the prediction of missing links.…

Quantum Physics · Physics 2023-06-27 Duarte Magano , João Moutinho , Bruno Coutinho

The theory of quasirandomness has greatly expanded from its inaugural graph theoretical setting to several different combinatorial objects such as hypergraphs, tournaments, permutations, etc. However, these quasirandomness variants have…

Combinatorics · Mathematics 2020-12-23 Leonardo N. Coregliano , Alexander A. Razborov

We study the transition matrix of a quantum walk on strongly regular graphs. It is proposed by Emms, Hancock, Severini and Wilson in 2006, that the spectrum of $S^+(U^3)$, a matrix based on the amplitudes of walks in the quantum walk,…

Combinatorics · Mathematics 2015-11-09 Chris Godsil , Krystal Guo , Tor G. J. Myklebust

The intention of the paper is to move a step towards a classification of network topologies that exhibit periodic quantum dynamics. We show that the evolution of a quantum system, whose hamiltonian is identical to the adjacency matrix of a…

Quantum Physics · Physics 2007-05-23 Nitin Saxena , Simone Severini , Igor Shparlinski

Using the spectral distribution associated with the adjacency matrix of graphs, we introduce a new method of calculation of amplitudes of continuous-time quantum walk on some rather important graphs, such as line, cycle graph $C_n$,…

Quantum Physics · Physics 2007-05-23 M. A. Jafarizadeh , S. Salimi

Continuous-time quantum walks on graphs is a generalization of continuous-time Markov chains on discrete structures. Moore and Russell proved that the continuous-time quantum walk on the $n$-cube is instantaneous exactly uniform mixing but…

Quantum Physics · Physics 2007-05-23 William Adamczak , Kevin Andrew , Peter Hernberg , Christino Tamon

We consider a discrete-time quantum walk, called the Grover walk, on a distance regular graph $X$. Given that $X$ has diameter $d$ and invertible adjacency matrix, we show that the square of the transition matrix of the Grover walk on $X$…

Combinatorics · Mathematics 2022-10-18 Hanmeng Zhan

Quantum channels, pivotal in information processing, describe transformations within quantum systems and enable secure communication and error correction. Ergodic and mixing properties elucidate their behavior. In this paper, we establish a…

Quantum Physics · Physics 2024-07-24 Abdessatar Souissi , Abdessatar Barhoumi

Electronic transport through chaotic quantum dots exhibits universal, system independent, properties, consistent with random matrix theory. The quantum transport can also be rooted, via the semiclassical approximation, in sums over the…

Chaotic Dynamics · Physics 2013-03-06 Gregory Berkolaiko , Jack Kuipers

We show that a number of conditions on oriented graphs, all of which are satisfied with high probability by randomly oriented graphs, are equivalent. These equivalences are similar to those given by Chung, Graham and Wilson in the case of…

Combinatorics · Mathematics 2011-08-12 Simon Griffiths

We establish and generalise several bounds for various random walk quantities including the mixing time and the maximum hitting time. Unlike previous analyses, our derivations are based on rather intuitive notions of local expansion…

Probability · Mathematics 2019-03-05 Thomas Sauerwald , Luca Zanetti

The adjacency matrix of a graph G is the Hamiltonian for a continuous-time quantum walk on the vertices of G. Although the entries of the adjacency matrix are integers, its eigenvalues are generally irrational and, because of this, the…

We demonstrate that a quantum graph exhibits a $\mathcal{PT}$-symmetry provided the coefficients in the condition describing the wave function matching at the vertices are circulant matrices; this symmetry is nontrivial if they are not…

Mathematical Physics · Physics 2021-10-04 Pavel Exner , Milos Tater

We set the ground for a theory of quantum walks on graphs- the generalization of random walks on finite graphs to the quantum world. Such quantum walks do not converge to any stationary distribution, as they are unitary and reversible.…

Quantum Physics · Physics 2016-09-08 Dorit Aharonov , Andris Ambainis , Julia Kempe , Umesh Vazirani

For a multivariate normal distribution, the sparsity of the covariance and precision matrices encodes complete information about independence and conditional independence properties. For general distributions, the covariance and precision…

Statistics Theory · Mathematics 2021-09-22 Rebecca E Morrison , Ricardo Baptista , Estelle L Basor

We study the set of probability distributions visited by a continuous-time quantum walk on graphs. An edge-weighted graph G is universal mixing if the instantaneous or average probability distribution of the quantum walk on G ranges over…

Quantum Physics · Physics 2008-06-13 W. Carlson , A. Ford , E. Harris , J. Rosen , C. Tamon , K. Wrobel