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Main Authors: Cleve, Richard, Ding, Zhiqian, Schaeffer, Luke
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2510.04921
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author Cleve, Richard
Ding, Zhiqian
Schaeffer, Luke
author_facet Cleve, Richard
Ding, Zhiqian
Schaeffer, Luke
contents The commutative depth model allows gates that commute with each other to be performed in parallel. We show how to compute Clifford operations in constant commutative depth more efficiently than was previously known. Bravyi, Maslov, and Nam [Phys. Rev. Lett. 129:230501, 2022] showed that every element of the Clifford group (on $n$ qubits) can be computed in commutative depth 23 and size $O(n^2)$. We show that the Prefix Sum problem can be computed in commutative depth 16 and size $O(n \log n)$, improving on the previous depth 18 and size $O(n^2)$ bounds. We also show that, for arbitrary Cliffords, the commutative depth bound can be reduced to 16. Finally, we show some lower bounds: that there exist Cliffords whose commutative depth is at least 4; and that there exist Cliffords for which any constant commutative depth circuit has size $Ω(n^2)$.
format Preprint
id arxiv_https___arxiv_org_abs_2510_04921
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Improved Clifford operations in constant commutative depth
Cleve, Richard
Ding, Zhiqian
Schaeffer, Luke
Quantum Physics
The commutative depth model allows gates that commute with each other to be performed in parallel. We show how to compute Clifford operations in constant commutative depth more efficiently than was previously known. Bravyi, Maslov, and Nam [Phys. Rev. Lett. 129:230501, 2022] showed that every element of the Clifford group (on $n$ qubits) can be computed in commutative depth 23 and size $O(n^2)$. We show that the Prefix Sum problem can be computed in commutative depth 16 and size $O(n \log n)$, improving on the previous depth 18 and size $O(n^2)$ bounds. We also show that, for arbitrary Cliffords, the commutative depth bound can be reduced to 16. Finally, we show some lower bounds: that there exist Cliffords whose commutative depth is at least 4; and that there exist Cliffords for which any constant commutative depth circuit has size $Ω(n^2)$.
title Improved Clifford operations in constant commutative depth
topic Quantum Physics
url https://arxiv.org/abs/2510.04921