Affine Equivalence in the Clifford Hierarchy

Fuente: arXiv
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Main Authors: Anderson, Jonas T., Connelly, Andrew
Format: Preprint
Published: 2025
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author Anderson, Jonas T.
Connelly, Andrew
author_facet Anderson, Jonas T.
Connelly, Andrew
contents In this paper we prove a collection of results on the structure of permutations in the Clifford Hierarchy. First, we leverage results from the cryptography literature on affine equivalence classes of 4-bit permutations which we use to find all 4-qubit permutations in the Clifford Hierarchy. We then use the classification of 4-qubit permutations and previous results on the structure of diagonal gates in the Clifford Hierarchy to prove that all 4-qubit gates in the third level of the Clifford Hierarchy are semi-Clifford. Finally, we introduce the formalism of cycle structures to permutations in the Clifford Hierarchy and prove a general structure theorem about them. We also classify many small cycle structures up to affine equivalence. Interestingly, this classification is independent of the number of qubits.
format Preprint
id arxiv_https___arxiv_org_abs_2507_14370
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Affine Equivalence in the Clifford Hierarchy
Anderson, Jonas T.
Connelly, Andrew
Quantum Physics
In this paper we prove a collection of results on the structure of permutations in the Clifford Hierarchy. First, we leverage results from the cryptography literature on affine equivalence classes of 4-bit permutations which we use to find all 4-qubit permutations in the Clifford Hierarchy. We then use the classification of 4-qubit permutations and previous results on the structure of diagonal gates in the Clifford Hierarchy to prove that all 4-qubit gates in the third level of the Clifford Hierarchy are semi-Clifford. Finally, we introduce the formalism of cycle structures to permutations in the Clifford Hierarchy and prove a general structure theorem about them. We also classify many small cycle structures up to affine equivalence. Interestingly, this classification is independent of the number of qubits.
title Affine Equivalence in the Clifford Hierarchy
topic Quantum Physics
url https://arxiv.org/abs/2507.14370