Quantum Discrete Variable Representations

Fuente: arXiv
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Autores principales: Pliś, Szymon, Zak, Emil
Formato: Preprint
Publicado: 2025
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author Pliś, Szymon
Zak, Emil
author_facet Pliś, Szymon
Zak, Emil
contents We present a fault-tolerant quantum algorithm for implementing the Discrete Variable Representation (DVR) transformation, a technique widely used in simulations of quantum-mechanical Hamiltonians. DVR provides a diagonal representation of local operators and enables sparse Hamiltonian structures, making it a powerful alternative to the finite basis representation (FBR), particularly in high-dimensional problems. While DVR has been extensively used in classical simulations, its quantum implementation, particularly using Gaussian quadrature grids, remains underexplored. We develop a quantum circuit that efficiently transforms FBR into DVR by following a recursive construction based on quantum arithmetic operations, and we compare this approach with methods that directly load DVR matrix elements using quantum read-only memory (QROM). We analyze the quantum resources, including T-gate and qubit counts, required for implementing the DVR unitary and discuss preferable choices of QROM-based and recursive-based methods for a given matrix size and precision. This study lays the groundwork for utilizing DVR Hamiltonians in quantum algorithms such as quantum phase estimation with block encoding.
format Preprint
id arxiv_https___arxiv_org_abs_2504_15841
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Quantum Discrete Variable Representations
Pliś, Szymon
Zak, Emil
Quantum Physics
Chemical Physics
Computational Physics
68Q12, 68Q17, 81P68, 81-08, 81-10, 81V74, 81V55
G.1.2; G.1.3; G.1.6; I.6.1
We present a fault-tolerant quantum algorithm for implementing the Discrete Variable Representation (DVR) transformation, a technique widely used in simulations of quantum-mechanical Hamiltonians. DVR provides a diagonal representation of local operators and enables sparse Hamiltonian structures, making it a powerful alternative to the finite basis representation (FBR), particularly in high-dimensional problems. While DVR has been extensively used in classical simulations, its quantum implementation, particularly using Gaussian quadrature grids, remains underexplored. We develop a quantum circuit that efficiently transforms FBR into DVR by following a recursive construction based on quantum arithmetic operations, and we compare this approach with methods that directly load DVR matrix elements using quantum read-only memory (QROM). We analyze the quantum resources, including T-gate and qubit counts, required for implementing the DVR unitary and discuss preferable choices of QROM-based and recursive-based methods for a given matrix size and precision. This study lays the groundwork for utilizing DVR Hamiltonians in quantum algorithms such as quantum phase estimation with block encoding.
title Quantum Discrete Variable Representations
topic Quantum Physics
Chemical Physics
Computational Physics
68Q12, 68Q17, 81P68, 81-08, 81-10, 81V74, 81V55
G.1.2; G.1.3; G.1.6; I.6.1
url https://arxiv.org/abs/2504.15841