Classifying Logical Gates in Quantum Codes via Cohomology Operations and Symmetry

Fuente: arXiv
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Main Authors: Hsin, Po-Shen, Kobayashi, Ryohei, Zhu, Guanyu
Format: Preprint
Published: 2024
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author Hsin, Po-Shen
Kobayashi, Ryohei
Zhu, Guanyu
author_facet Hsin, Po-Shen
Kobayashi, Ryohei
Zhu, Guanyu
contents We systematically construct and classify fault-tolerant logical gates implemented by constant-depth circuits for quantum codes using cohomology operations and symmetry. These logical gates are obtained from unitary operators given by symmetry-protected topological responses, which correspond to generators of group cohomology and can be expressed explicitly on the lattice using cohomology operations including cup product, Steenrod squares and new combinations of higher cup products called higher Pontryagin powers. Our study covers most types of the cohomology operations in the literature. This hence gives rise to logical $C^{n-1}Z$ gates in $n$ copies of quantum codes via the $n$-fold cup product in the usual color code paradigm, as well as several new classes of diagonal and non-diagonal logical gates in increasing Clifford hierarchies beyond the color code paradigm, including the logical $R_k$ and multi-controlled $C^m R_k$ gates for codes defined in projective spaces. Implementing these gates could make it more efficient to compile specific types of quantum algorithms such as Shor's algorithm. We further extend the construction to quantum codes with boundaries, which generalizes the folding approach in color codes. We also present a formalism for addressable and parallelizable logical gates in LDPC codes via higher-form symmetries. We further construct logical Clifford gates in expander-based codes including the asymptotically good LDPC codes and hypergraph-product codes. As a byproduct, we find new topological responses of finite higher-form symmetries using higher Pontryagin powers.
format Preprint
id arxiv_https___arxiv_org_abs_2411_15848
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Classifying Logical Gates in Quantum Codes via Cohomology Operations and Symmetry
Hsin, Po-Shen
Kobayashi, Ryohei
Zhu, Guanyu
Quantum Physics
Strongly Correlated Electrons
High Energy Physics - Theory
Quantum Algebra
We systematically construct and classify fault-tolerant logical gates implemented by constant-depth circuits for quantum codes using cohomology operations and symmetry. These logical gates are obtained from unitary operators given by symmetry-protected topological responses, which correspond to generators of group cohomology and can be expressed explicitly on the lattice using cohomology operations including cup product, Steenrod squares and new combinations of higher cup products called higher Pontryagin powers. Our study covers most types of the cohomology operations in the literature. This hence gives rise to logical $C^{n-1}Z$ gates in $n$ copies of quantum codes via the $n$-fold cup product in the usual color code paradigm, as well as several new classes of diagonal and non-diagonal logical gates in increasing Clifford hierarchies beyond the color code paradigm, including the logical $R_k$ and multi-controlled $C^m R_k$ gates for codes defined in projective spaces. Implementing these gates could make it more efficient to compile specific types of quantum algorithms such as Shor's algorithm. We further extend the construction to quantum codes with boundaries, which generalizes the folding approach in color codes. We also present a formalism for addressable and parallelizable logical gates in LDPC codes via higher-form symmetries. We further construct logical Clifford gates in expander-based codes including the asymptotically good LDPC codes and hypergraph-product codes. As a byproduct, we find new topological responses of finite higher-form symmetries using higher Pontryagin powers.
title Classifying Logical Gates in Quantum Codes via Cohomology Operations and Symmetry
topic Quantum Physics
Strongly Correlated Electrons
High Energy Physics - Theory
Quantum Algebra
url https://arxiv.org/abs/2411.15848