Exponentially Accelerated Sampling of Pauli Strings for Nonstabilizerness

Fuente: arXiv
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Autori principali: Xiao, Zhenyu, Ryu, Shinsei
Natura: Preprint
Pubblicazione: 2026
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author Xiao, Zhenyu
Ryu, Shinsei
author_facet Xiao, Zhenyu
Ryu, Shinsei
contents Quantum magic, quantified by nonstabilizerness, measures departures from stabilizer structure and underlies potential quantum speedups. We introduce an efficient classical framework for computing stabilizer Rényi entropies and stabilizer nullity of generic $N$-qubit wavefunctions. The method combines the fast Walsh-Hadamard transform with an exact partition of Pauli operators, reducing the average cost per sampled Pauli string from $\mathcal{O}(2^N)$ to $\mathcal{O}(N)$. We further develop a Monte Carlo estimator with Clifford preconditioning and find that the required number of samples shows no visible growth with $N$ in our benchmarks. Applying the method to $T$-doped random Clifford circuits, we identify the scrambling ratio $η$ (Clifford gates per $T$ gate) as the key parameter governing magic growth. Each $T$ gate approaches its dilute-limit nonstabilizerness power with only modest Clifford scrambling. Our approach enables quantitative studies of magic in highly entangled states and long-time nonequilibrium dynamics.
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id arxiv_https___arxiv_org_abs_2601_00761
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Exponentially Accelerated Sampling of Pauli Strings for Nonstabilizerness
Xiao, Zhenyu
Ryu, Shinsei
Quantum Physics
Mesoscale and Nanoscale Physics
Statistical Mechanics
Quantum magic, quantified by nonstabilizerness, measures departures from stabilizer structure and underlies potential quantum speedups. We introduce an efficient classical framework for computing stabilizer Rényi entropies and stabilizer nullity of generic $N$-qubit wavefunctions. The method combines the fast Walsh-Hadamard transform with an exact partition of Pauli operators, reducing the average cost per sampled Pauli string from $\mathcal{O}(2^N)$ to $\mathcal{O}(N)$. We further develop a Monte Carlo estimator with Clifford preconditioning and find that the required number of samples shows no visible growth with $N$ in our benchmarks. Applying the method to $T$-doped random Clifford circuits, we identify the scrambling ratio $η$ (Clifford gates per $T$ gate) as the key parameter governing magic growth. Each $T$ gate approaches its dilute-limit nonstabilizerness power with only modest Clifford scrambling. Our approach enables quantitative studies of magic in highly entangled states and long-time nonequilibrium dynamics.
title Exponentially Accelerated Sampling of Pauli Strings for Nonstabilizerness
topic Quantum Physics
Mesoscale and Nanoscale Physics
Statistical Mechanics
url https://arxiv.org/abs/2601.00761