Strongly cospectral vertices

C Godsil, J Smith - arXiv preprint arXiv:1709.07975, 2017 - arxiv.org
Two vertices $ a $ and $ b $ in a graph $ X $ are cospectral if the vertex-deleted subgraphs
$ X\setminus a $ and $ X\setminus b $ have the same characteristic polynomial. In this …

Selected open problems in continuous-time quantum walks

G Coutinho, K Guo - Special Matrices, 2024 - degruyter.com
Quantum walks on graphs are fundamental to quantum computing and have led to many
interesting open problems in algebraic graph theory. This review article highlights three key …

Irrational quantum walks

G Coutinho, PF Baptista, C Godsil, TJ Spier… - SIAM Journal on Applied …, 2023 - SIAM
The adjacency matrix of a graph is the Hamiltonian for a continuous-time quantum walk on
the vertices of. Although the entries of the adjacency matrix are integers, its eigenvalues are …

[PDF][PDF] Strongly cospectral vertices.

CD Godsil, J Smith - Australas. J Comb., 2024 - ajc.maths.uq.edu.au
Two vertices a and b in a graph X are cospectral if the vertex-deleted subgraphs X\a and X\b
have the same characteristic polynomial. In this paper we investigate a strengthening of this …

Unexpected averages of mixing matrices

P Baptista, G Coutinho, V Marques - Quantum Information Processing, 2024 - Springer
The (standard) average mixing matrix of a continuous-time quantum walk is computed by
taking the expected value of the mixing matrices of the walk under the uniform sampling …

Equivalent Laplacian and adjacency quantum walks on irregular graphs

TG Wong, J Lockhart - Physical Review A, 2021 - APS
The continuous-time quantum walk is a particle evolving by Schrödinger's equation in
discrete space. Encoding the space as a graph of vertices and edges, the Hamiltonian is …

[PDF][PDF] Diagonal entries of the average mixing matrix.

CD Godsil, K Guo, M Sobchuk - Australas. J Comb., 2023 - ajc.maths.uq.edu.au
We study the diagonal entries of the average mixing matrix of continuous quantum walks.
The average mixing matrix is a graph invariant; it is the sum of the Schur squares of spectral …

The average search probabilities of discrete-time quantum walks

H Zhan - Quantum Information Processing, 2022 - Springer
We study the average probability that a discrete-time quantum walk finds a marked vertex on
a graph. We first show that, for a regular graph, the spectrum of the transition matrix is …

Average mixing matrix of trees

C Godsil, K Guo, J Sinkovic - arXiv preprint arXiv:1709.07907, 2017 - arxiv.org
We investigate the rank of the average mixing matrix of trees, with all eigenvalues distinct.
The rank of the average mixing matrix of a tree on $ n $ vertices with $ n $ distinct …

Diagonal entries of the average mixing matrix

C Godsil, K Guo, M Sobchuk - arXiv preprint arXiv:1910.02039, 2019 - arxiv.org
We study the diagonal entries of the average mixing matrix of continuous quantum walks.
The average mixing matrix is a graph invariant; it is the sum of the Schur squares of spectral …