Eigenvalues and eigenvectors of complex Hadamard matrices

Fuente: arXiv
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Main Authors: Liang, Mengfan, Chen, Lin
Format: Preprint
Published: 2024
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author Liang, Mengfan
Chen, Lin
author_facet Liang, Mengfan
Chen, Lin
contents Characterizing the $6\times 6$ complex Hadamard matrices (CHMs) is an open problem in linear algebra and quantum information. In this paper, we investigate the eigenvalues and eigenvectors of CHMs. We show that any $n\times n$ CHM with dephased form has two constant eigenvalues $\pm\sqrt{n}$ and has two constant eigenvectors. We obtain the maximum numbers of identical eigenvalues of $6\times 6$ CHMs with dephased form and we extend this result to arbitrary dimension. We also show that there is no $6\times 6$ CHM with four identical eigenvalues. We conjecture that the eigenvalues and eigenvectors of $6\times 6$ CHMs will lead to the complete classification of $6\times 6$ CHMs.
format Preprint
id arxiv_https___arxiv_org_abs_2408_10471
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Eigenvalues and eigenvectors of complex Hadamard matrices
Liang, Mengfan
Chen, Lin
Quantum Physics
Mathematical Physics
Characterizing the $6\times 6$ complex Hadamard matrices (CHMs) is an open problem in linear algebra and quantum information. In this paper, we investigate the eigenvalues and eigenvectors of CHMs. We show that any $n\times n$ CHM with dephased form has two constant eigenvalues $\pm\sqrt{n}$ and has two constant eigenvectors. We obtain the maximum numbers of identical eigenvalues of $6\times 6$ CHMs with dephased form and we extend this result to arbitrary dimension. We also show that there is no $6\times 6$ CHM with four identical eigenvalues. We conjecture that the eigenvalues and eigenvectors of $6\times 6$ CHMs will lead to the complete classification of $6\times 6$ CHMs.
title Eigenvalues and eigenvectors of complex Hadamard matrices
topic Quantum Physics
Mathematical Physics
url https://arxiv.org/abs/2408.10471