Quantum-classical algorithm interpolation for spatial search
Abstract
Quantum-walk algorithms can quadratically reduce the dependence of spatial search on the classical hitting time HT. Realising this speedup using standard quantum-walk algorithms, however, requires deep coherent circuits, limiting their applicability on near-term and early fault-tolerant quantum devices. We derive a parameterised family of hybrid quantum-classical spatial search algorithms that continuously interpolates between the classical and fully coherent quantum regimes, trading off circuit depth for total query complexity. For any γ∈[0,1], our algorithms use circuits of depth Õ(HTγ/2) and find a marked vertex with constant success probability at total cost Õ(HT1−γS + HT1−γ/2(U + C)), where S, U, and C denote the setup, update, and checking costs, respectively. We also derive an optimal continuous depth-query trade-off for fixed-point amplitude amplification, providing a potential building block for other hybrid designs.
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BibTeX
@misc{ramos2026quantumclassical,
title = {{Quantum-classical algorithm interpolation for spatial search}},
author = {Diogo Ramos and Duarte Magano},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.19255},
eprint = {2610.19255},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.19255},
}
RIS
TY - UNPB
TI - Quantum-classical algorithm interpolation for spatial search
AU - Diogo Ramos
AU - Duarte Magano
PY - 2026
DA - 2026/10/13
PB - arXiv
DO - 10.48550/arxiv.2610.19255
UR - https://arxiv.org/abs/2610.19255
AB - Quantum-walk algorithms can quadratically reduce the dependence of spatial search on the classical hitting time HT. Realising this speedup using standard quantum-walk algorithms, however, requires deep coherent circuits, limiting their applicability on near-term and early fault-tolerant quantum devices. We derive a parameterised family of hybrid quantum-classical spatial search algorithms that continuously interpolates between the classical and fully coherent quantum regimes, trading off circuit depth for total query complexity. For any γ∈[0,1], our algorithms use circuits of depth Õ(HT^γ/2) and find a marked vertex with constant success probability at total cost Õ(HT^1−γS + HT^1−γ/2(U + C)), where S, U, and C denote the setup, update, and checking costs, respectively. We also derive an optimal continuous depth-query trade-off for fixed-point amplitude amplification, providing a potential building block for other hybrid designs.
ER -