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Main Authors: Huang, Xuyang, Li, Han-Ze, Lee, Ching Hua, Zhong, Jian-Xin
Format: Preprint
Published: 2025
Subjects:
Online Access:https://arxiv.org/abs/2512.24685
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author Huang, Xuyang
Li, Han-Ze
Lee, Ching Hua
Zhong, Jian-Xin
author_facet Huang, Xuyang
Li, Han-Ze
Lee, Ching Hua
Zhong, Jian-Xin
contents Quantum advantage is widely understood to rely on key quantum resources beyond entanglement, among which nonstabilizerness (quantum ``magic'') plays a central role in enabling universal quantum computation. However, the exact evaluation of the second-order stabilizer Rényi entropy for generic many-body quantum states remains computationally challenging, with brute-force methods scaling as $\mathcal O(8^N)$ for an $N$-qubit state. Here we develop a deterministic and exact algorithm that reduces this cost to $\mathcal{O}(N4^N)$ while retaining natural parallelism. This advance enables high-precision exact calculations for generic state vectors at medium system sizes, and provides a practical tool for investigating the scaling, phase structure, and nonequilibrium dynamics of quantum magic in many-body systems.
format Preprint
id arxiv_https___arxiv_org_abs_2512_24685
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle A fast and exact approach for stabilizer Rényi entropy via the XOR-FWHT algorithm
Huang, Xuyang
Li, Han-Ze
Lee, Ching Hua
Zhong, Jian-Xin
Quantum Physics
Quantum advantage is widely understood to rely on key quantum resources beyond entanglement, among which nonstabilizerness (quantum ``magic'') plays a central role in enabling universal quantum computation. However, the exact evaluation of the second-order stabilizer Rényi entropy for generic many-body quantum states remains computationally challenging, with brute-force methods scaling as $\mathcal O(8^N)$ for an $N$-qubit state. Here we develop a deterministic and exact algorithm that reduces this cost to $\mathcal{O}(N4^N)$ while retaining natural parallelism. This advance enables high-precision exact calculations for generic state vectors at medium system sizes, and provides a practical tool for investigating the scaling, phase structure, and nonequilibrium dynamics of quantum magic in many-body systems.
title A fast and exact approach for stabilizer Rényi entropy via the XOR-FWHT algorithm
topic Quantum Physics
url https://arxiv.org/abs/2512.24685