Fast and exact approach for stabilizer Rényi entropy via the XOR-FWHT algorithm
- 1Shanghai University
- 2National University of Singapore
Abstract
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 deterministic evaluation of the second-order stabilizer Rényi entropy for generic many-body quantum states remains computationally challenging, with brute-force methods scaling as O ( 8 N ) = O ( d 3 ) for an N -qubit state with d = 2 N . Here, we develop an exact algebraic reformulation and a deterministic numerical algorithm, numerically exact up to floating-point roundoff, that reduces this cost to O ( N 4 N ) = O ( d 2 log 2 d ) while retaining natural parallelism. This is an exponential speedup, although the scaling remains exponential in the number of qubits. This advance enables high-precision calculations for generic state vectors at medium system sizes and provides a practical tool for investigating the scaling and nonequilibrium dynamics of quantum magic in many-body systems.
Versions
Related
- Rényi Multi-entropy for Stabilizer States: A Finite Field Gauss Sum Problem
- Efficient Pauli Truncation from Operator Stabilizer Rényi Entropy
- Classical Root Systems Reveal Defect-Junction Data in Stabilizer Rényi Entropy
- Stabilizer Rényi Entropy Without a Phase Reference
- Stabilizer Rényi moments beyond entanglement
BibTeX
@article{huang2026fast,
title = {{Fast and exact approach for stabilizer Rényi entropy via the XOR-FWHT algorithm}},
author = {Xuyang Huang and Han-Ze Li and Ching Hua Lee and Jian-Xin Zhong},
journal = {Physical Review Research},
year = {2026},
month = oct,
doi = {10.1103/f7ss-6tl1},
url = {https://link.aps.org/doi/10.1103/f7ss-6tl1},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Fast and exact approach for stabilizer Rényi entropy via the XOR-FWHT algorithm
AU - Xuyang Huang
AU - Han-Ze Li
AU - Ching Hua Lee
AU - Jian-Xin Zhong
PY - 2026
DA - 2026/10/19
JO - Physical Review Research
DO - 10.1103/f7ss-6tl1
UR - https://link.aps.org/doi/10.1103/f7ss-6tl1
AB - 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 deterministic evaluation of the second-order stabilizer Rényi entropy for generic many-body quantum states remains computationally challenging, with brute-force methods scaling as O ( 8 N ) = O ( d 3 ) for an N -qubit state with d = 2 N . Here, we develop an exact algebraic reformulation and a deterministic numerical algorithm, numerically exact up to floating-point roundoff, that reduces this cost to O ( N 4 N ) = O ( d 2 log 2 d ) while retaining natural parallelism. This is an exponential speedup, although the scaling remains exponential in the number of qubits. This advance enables high-precision calculations for generic state vectors at medium system sizes and provides a practical tool for investigating the scaling and nonequilibrium dynamics of quantum magic in many-body systems.
SN - 2643-1564
ER -