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arXiv · 2506.21282

On two maximally entangled couples

Felix Huber·Jens Siewert
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Abstract

In a seminal article, Higuchi and Sudbery showed that a pure four-qubit state can not be maximally entangled across every bipartition. Such states are now known as absolutely maximally entangled (AME) states. Here we give a series of old and new proofs of the fact that no four-qubit AME state exists. These are based on invariant theory, methods from coding theory, and basic properties from linear algebra such as the Pauli commutation relations.

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Felix Huber, Jens Siewert. 2025-06-26. On two maximally entangled couples. https://doi.org/10.1088/2058-9565%2Fae23f4

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