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The paper investigates perfect state transfer (PST) in Grover walks on Cayley graphs over the dihedral group $D_n$. The Grover walk is a discrete-time quantum walk widely studied in quantum information processing. A Cayley graph…

Combinatorics · Mathematics 2026-05-05 Koushik Bhakta , Bikash Bhattacharjya , Xiwang Cao

The evolution of certain pair state in a quantum network with isomorphic branches, governed by the Heisenberg $XY$ Hamiltonian, depends solely on the local structure, and it remains unaffected even if the global structure is altered. All…

Quantum Physics · Physics 2024-12-10 Hiranmoy Pal , Sarojini Mohapatra

A simple method for transmitting quantum states within a quantum computer is via a quantum spin chain---that is, a path on $n$ vertices. Unweighted paths are of limited use, and so a natural generalization is to consider weighted paths;…

Quantum Physics · Physics 2019-03-26 Steve Kirkland , Darian McLaren , Rajesh Pereira , Sarah Plosker , Xiaohong Zhang

In a continuous-time quantum walk on a network of qubits, pretty good state transfer is the phenomenon of state transfer between two vertices with fidelity arbitrarily close to 1. We construct families of graphs to demonstrate that there is…

Combinatorics · Mathematics 2023-05-24 Ada Chan , Peter Sin

The quadratic unitary Cayley graph $\mathcal{G}_{\mathbb{Z}_n}$ has vertex set $\mathbb{Z}_n: =\{0,1, \ldots ,n-1\}$, where two vertices $u$ and $v$ are adjacent if and only if $u - v$ or $v-u$ is a square of some units in $\mathbb{Z}_n$.…

Combinatorics · Mathematics 2025-08-12 Koushik Bhakta , Bikash Bhattacharjya

Perfect state transfer between two marked vertices of a graph by means of discrete-time quantum walk is analyzed. We consider the quantum walk search algorithm with two marked vertices, sender and receiver. It is shown by explicit…

Quantum Physics · Physics 2016-08-02 Martin Stefanak , Stanislav Skoupy

We show that deciding whether a graph admits perfect state transfer can be done in polynomial time with respect to the size of the graph on a classical computer.

Combinatorics · Mathematics 2021-12-08 Gabriel Coutinho , Chris Godsil

Quantum walks, an important tool in quantum computing, have been very successfully investigated using techniques in algebraic graph theory. We are motivated by the study of state transfer in continuous-time quantum walks, which is…

Combinatorics · Mathematics 2017-10-09 Chris Godsil , Krystal Guo , Mark Kempton , Gabor Lippner

Let $G$ be a graph with adjacency matrix $A$. The transition matrix corresponding to $G$ is defined by $H(t):=\exp{\left(itA\right)}$, $t\in\Rl$. The graph $G$ is said to have perfect state transfer (PST) from a vertex $u$ to another vertex…

Combinatorics · Mathematics 2019-01-08 Hiranmoy Pal , Bikash Bhattacharjya

The unitary Cayley graph has vertex set $\{0,1, \hdots ,n-1\}$, where two vertices $u$ and $v$ are adjacent if $\gcd(u - v, n) = 1$. In this paper, we study periodicity and perfect state transfer of Grover walks on the unitary Cayley…

Combinatorics · Mathematics 2024-06-26 Koushik Bhakta , Bikash Bhattacharjya

There is perfect state transfer between two vertices of a graph, if a single excitation can travel with fidelity one between the corresponding sites of a spin system modeled by the graph. When the excitation is back at the initial site, for…

Quantum Physics · Physics 2011-09-30 Simone Severini

In this paper, we characterize perfect state transfer in Cayley graphs for abelian groups that have a cyclic Sylow-2-subgroup. This generalizes a result of Ba\v{s}i\'c from 2013 where he provides a similar characterization for Cayley graphs…

Combinatorics · Mathematics 2022-12-14 Arnbjörg Soffía Árnadóttir , Chris Godsil

Following the prescription of Ref. \cite{PST} in which perfect state transference (PST) of a qubit over distance regular spin networks was discussed, in this paper PST of an arbitrary $d$-level quantum state (qudit) over antipodes of more…

Quantum Physics · Physics 2009-11-13 M. A. Jafarizadeh , R. Sufiani , S. F. Taghavi , E. Barati

Pretty good state transfer in networks of qubits occurs when a continuous-time quantum walk allows the transmission of a qubit state from one node of the network to another, with fidelity arbitrarily close to 1. We prove that in a…

Quantum Physics · Physics 2018-06-22 Leonardo Banchi , Gabriel Coutinho , Chris Godsil , Simone Severini

We consider graphs with two cut vertices joined by a path with one or two edges, and prove that there can be no quantum perfect state transfer between these vertices, unless the graph has no other vertex. We achieve this result by applying…

Quantum Physics · Physics 2021-12-08 Gabriel Coutinho , Chris Godsil , Emanuel Juliano , Christopher M. van Bommel

We introduce the concept of group state transfer on graphs, summarize its relationship to other concepts in the theory of quantum walks, set up a basic theory, and discuss examples. Let $X$ be a graph with adjacency matrix $A$ and consider…

Quantum Physics · Physics 2021-03-17 Luke C. Brown , William J. Martin , Duncan Wright

A weighted graph $G$ with countable vertex set is bounded if there is an upper bound on the maximum of the sum of absolute values of all edge weights incident to a vertex in $G$. In this paper, we prove a fundamental result on equitable…

Combinatorics · Mathematics 2025-10-08 Chris Godsil , Steve Kirkland , Sarojini Mohapatra , Hermie Monterde , Hiranmoy Pal

Let $G$ be a graph of order $n,$ and let $q_{1}(G) \geq ...\geq q_{n}(G) $ be the eigenvalues of the $Q$-matrix of $G$, also known as the signless Laplacian of $G.$ In this paper we give a necessary and sufficient condition for the equality…

Spectral Theory · Mathematics 2012-12-13 Leonardo S. de Lima , Vladimir Nikiforov

Quantum state transfer between different sites is a significant problem for quantum networks and quantum computers. By selecting quantum walks with two coins as the basic model and two coin spaces as the communication carriers, we…

Quantum Physics · Physics 2019-12-13 Yun Shang , Meng Li

We present a general formalism to the problem of perfect state-transfer (PST), where the state involves multiple excitations of the quantum network. A key feature of our formalism is that it allows for inclusion of nontrivial interactions…

Quantum Physics · Physics 2011-08-04 T. Brougham , G. M. Nikolopoulos , I. Jex
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