Approximate Sparse State Preparation with the Grover-Rudolph Algorithm

Fuente: arXiv
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Hauptverfasser: Ramacciotti, Debora, Steinbach, Martin, Temesi, Bence, Lefterovici, Andreea-Iulia, Rotundo, Antonio F.
Format: Preprint
Veröffentlicht: 2026
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author Ramacciotti, Debora
Steinbach, Martin
Temesi, Bence
Lefterovici, Andreea-Iulia
Rotundo, Antonio F.
author_facet Ramacciotti, Debora
Steinbach, Martin
Temesi, Bence
Lefterovici, Andreea-Iulia
Rotundo, Antonio F.
contents Sparse quantum state preparation is a common subroutine in quantum algorithms, where classical data with few nonzero entries must be loaded into a quantum state. In this work, we consider the Grover-Rudolph algorithm, which has recently been shown to efficiently prepare sparse states, and we propose two improvements. First, we extend an existing gate-merging procedure by allowing rotations to merge with virtual zero-angle gates on unreachable branches of the preparation tree, reducing the number of CNOTs and control qubits. Second, we introduce an approximate variant in which rotations with similar but not identical angles are merged at the cost of a small, controllable error in the prepared state. We derive a classically computable estimate of the resulting overlap with the target state, which is used to guide the merging decisions.
format Preprint
id arxiv_https___arxiv_org_abs_2604_24973
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Approximate Sparse State Preparation with the Grover-Rudolph Algorithm
Ramacciotti, Debora
Steinbach, Martin
Temesi, Bence
Lefterovici, Andreea-Iulia
Rotundo, Antonio F.
Quantum Physics
Sparse quantum state preparation is a common subroutine in quantum algorithms, where classical data with few nonzero entries must be loaded into a quantum state. In this work, we consider the Grover-Rudolph algorithm, which has recently been shown to efficiently prepare sparse states, and we propose two improvements. First, we extend an existing gate-merging procedure by allowing rotations to merge with virtual zero-angle gates on unreachable branches of the preparation tree, reducing the number of CNOTs and control qubits. Second, we introduce an approximate variant in which rotations with similar but not identical angles are merged at the cost of a small, controllable error in the prepared state. We derive a classically computable estimate of the resulting overlap with the target state, which is used to guide the merging decisions.
title Approximate Sparse State Preparation with the Grover-Rudolph Algorithm
topic Quantum Physics
url https://arxiv.org/abs/2604.24973