Block encoding of sparse matrices with a periodic diagonal structure

Fuente: arXiv
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Autori principali: Zecchi, Alessandro Andrea, Sanavio, Claudio, Cappelli, Luca, Perotto, Simona, Roggero, Alessandro, Succi, Sauro
Natura: Preprint
Pubblicazione: 2026
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author Zecchi, Alessandro Andrea
Sanavio, Claudio
Cappelli, Luca
Perotto, Simona
Roggero, Alessandro
Succi, Sauro
author_facet Zecchi, Alessandro Andrea
Sanavio, Claudio
Cappelli, Luca
Perotto, Simona
Roggero, Alessandro
Succi, Sauro
contents Block encoding is a successful technique used in several powerful quantum algorithms. In this work we provide an explicit quantum circuit for block encoding a sparse matrix with a periodic diagonal structure. The proposed methodology is based on the linear combination of unitaries (LCU) framework and on an efficient unitary operator used to project the complex exponential at a frequency $ω$ multiplied by the computational basis into its real and imaginary components. We demonstrate a distinct computational advantage with a $\mathcal{O}(\text{poly}(n))$ gate complexity, where $n$ is the number of qubits, in the worst-case scenario used for banded matrices, and $\mathcal{O}(n)$ when dealing with a simple diagonal matrix, compared to the exponential scaling of general-purpose methods for dense matrices. Various applications for the presented methodology are discussed in the context of solving differential problems such as the advection-diffusion-reaction (ADR) dynamics, using quantum algorithms with optimal scaling, e.g., quantum singular value transformation (QSVT). Numerical results are used to validate the analytical formulation.
format Preprint
id arxiv_https___arxiv_org_abs_2602_10589
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Block encoding of sparse matrices with a periodic diagonal structure
Zecchi, Alessandro Andrea
Sanavio, Claudio
Cappelli, Luca
Perotto, Simona
Roggero, Alessandro
Succi, Sauro
Quantum Physics
Numerical Analysis
Block encoding is a successful technique used in several powerful quantum algorithms. In this work we provide an explicit quantum circuit for block encoding a sparse matrix with a periodic diagonal structure. The proposed methodology is based on the linear combination of unitaries (LCU) framework and on an efficient unitary operator used to project the complex exponential at a frequency $ω$ multiplied by the computational basis into its real and imaginary components. We demonstrate a distinct computational advantage with a $\mathcal{O}(\text{poly}(n))$ gate complexity, where $n$ is the number of qubits, in the worst-case scenario used for banded matrices, and $\mathcal{O}(n)$ when dealing with a simple diagonal matrix, compared to the exponential scaling of general-purpose methods for dense matrices. Various applications for the presented methodology are discussed in the context of solving differential problems such as the advection-diffusion-reaction (ADR) dynamics, using quantum algorithms with optimal scaling, e.g., quantum singular value transformation (QSVT). Numerical results are used to validate the analytical formulation.
title Block encoding of sparse matrices with a periodic diagonal structure
topic Quantum Physics
Numerical Analysis
url https://arxiv.org/abs/2602.10589