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Orthogonal maximal abelian *-subalgebras of the 6x6 matrices

Kyle Beauchamp·Remus Nicoara
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Abstract

We construct new pairs of orthogonal maximal abelian $*$-subalgebras of $M_6(\mathbb C)$, by classifying all self-adjoint complex Hadamard matrices of order 6. In particular, we exhibit a non-affine one-parameter family of non-equivalent Hadamard matrices of order 6. In the last part of the paper we present other previously unknown examples of complex Hadamard matrices of higher orders.

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Kyle Beauchamp, Remus Nicoara. 2006-09-03. Orthogonal maximal abelian *-subalgebras of the 6x6 matrices. https://arxiv.org/abs/math/0609076

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