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Main Authors: Wang, Cai-Hong, Yuan, Jiang-Tao, Ma, Zhi-Hao, Fei, Shao-Ming, Bu, Shang-Quan
Format: Preprint
Published: 2023
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Online Access:https://arxiv.org/abs/2303.13304
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author Wang, Cai-Hong
Yuan, Jiang-Tao
Ma, Zhi-Hao
Fei, Shao-Ming
Bu, Shang-Quan
author_facet Wang, Cai-Hong
Yuan, Jiang-Tao
Ma, Zhi-Hao
Fei, Shao-Ming
Bu, Shang-Quan
contents It is known that every (single-qudit) Clifford operator maps the full set of generalized Pauli matrices (GPMs) to itself under unitary conjugation, which is an important quantum operation and plays a crucial role in quantum computation and information. However, in many quantum information processing tasks, it is required that a specific set of GPMs be mapped to another such set under conjugation, instead of the entire set. We formalize this by introducing local Clifford operator, which maps a given $n$-GPM set to another such set under unitary conjugation. We establish necessary and sufficient conditions for such an operator to transform a pair of GPMs, showing that these local Clifford operators admit a classical matrix representation, analogous to the classical (or symplectic) representation of standard (single-qudit) Clifford operators. Furthermore, we demonstrate that any local Clifford operator acting on an $n$-GPM ($n\geq 2$) set can be decomposed into a product of standard Clifford operators and a local Clifford operator acting on a pair of GPMs. This decomposition provides a complete classical characterization of unitary conjugation mappings between $n$-GPM sets. As a key application, we use this framework to address the local unitary equivalence (LU-equivalence) of sets of generalized Bell states (GBSs). We prove that the 31 equivalence classes of $4$-GBS sets in bipartite system $\mathbb{C}^{6}\otimes \mathbb{C}^{6}$ previously identified via Clifford operators are indeed distinct under LU-equivalence, confirming that this classification is complete.
format Preprint
id arxiv_https___arxiv_org_abs_2303_13304
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Classical representation of local Clifford operators
Wang, Cai-Hong
Yuan, Jiang-Tao
Ma, Zhi-Hao
Fei, Shao-Ming
Bu, Shang-Quan
Quantum Physics
81P40, 81P18
It is known that every (single-qudit) Clifford operator maps the full set of generalized Pauli matrices (GPMs) to itself under unitary conjugation, which is an important quantum operation and plays a crucial role in quantum computation and information. However, in many quantum information processing tasks, it is required that a specific set of GPMs be mapped to another such set under conjugation, instead of the entire set. We formalize this by introducing local Clifford operator, which maps a given $n$-GPM set to another such set under unitary conjugation. We establish necessary and sufficient conditions for such an operator to transform a pair of GPMs, showing that these local Clifford operators admit a classical matrix representation, analogous to the classical (or symplectic) representation of standard (single-qudit) Clifford operators. Furthermore, we demonstrate that any local Clifford operator acting on an $n$-GPM ($n\geq 2$) set can be decomposed into a product of standard Clifford operators and a local Clifford operator acting on a pair of GPMs. This decomposition provides a complete classical characterization of unitary conjugation mappings between $n$-GPM sets. As a key application, we use this framework to address the local unitary equivalence (LU-equivalence) of sets of generalized Bell states (GBSs). We prove that the 31 equivalence classes of $4$-GBS sets in bipartite system $\mathbb{C}^{6}\otimes \mathbb{C}^{6}$ previously identified via Clifford operators are indeed distinct under LU-equivalence, confirming that this classification is complete.
title Classical representation of local Clifford operators
topic Quantum Physics
81P40, 81P18
url https://arxiv.org/abs/2303.13304