Quantum Power Iteration Unified Using Generalized Quantum Signal Processing

Fuente: arXiv
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Main Authors: Khinevich, Viktor, Lee, Yasunori, Yoshioka, Nobuyuki, Mizukami, Wataru
Format: Preprint
Published: 2025
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author Khinevich, Viktor
Lee, Yasunori
Yoshioka, Nobuyuki
Mizukami, Wataru
author_facet Khinevich, Viktor
Lee, Yasunori
Yoshioka, Nobuyuki
Mizukami, Wataru
contents We propose a unifying framework for the state preparation using quantum power method algorithms based on generalized quantum signal processing (GQSP). We apply GQSP to realize quantum analogs of classical power iteration, power Lanczos, inverse iteration, and folded spectrum methods, all within a single coherent framework. GQSP allows efficient realization of methods that require complex polynomials, while avoiding the limitations of approaches based on linear combinations of time-evolution operators. Our constructions, including a Trotter-decomposition-free quantum inverse iteration, achieve near-optimal query scaling, together with reduced qubit requirements. The same formalism yields a quantum folded spectrum method for excited state preparation that avoids explicitly forming powers of the Hamiltonian or performing variational optimization. We provide a theoretical analysis of success probabilities and resource scaling, and we validate the methods numerically using molecular Hamiltonians. The results show that quantum power Lanczos lowers the computational cost and provides robust convergence compared to naive quantum power iteration. Our findings reveal that GQSP-based implementations of power methods combine scalability, flexibility, and robust convergence, paving the way for practical initial state preparations on fault-tolerant quantum devices.
format Preprint
id arxiv_https___arxiv_org_abs_2507_11142
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Quantum Power Iteration Unified Using Generalized Quantum Signal Processing
Khinevich, Viktor
Lee, Yasunori
Yoshioka, Nobuyuki
Mizukami, Wataru
Quantum Physics
We propose a unifying framework for the state preparation using quantum power method algorithms based on generalized quantum signal processing (GQSP). We apply GQSP to realize quantum analogs of classical power iteration, power Lanczos, inverse iteration, and folded spectrum methods, all within a single coherent framework. GQSP allows efficient realization of methods that require complex polynomials, while avoiding the limitations of approaches based on linear combinations of time-evolution operators. Our constructions, including a Trotter-decomposition-free quantum inverse iteration, achieve near-optimal query scaling, together with reduced qubit requirements. The same formalism yields a quantum folded spectrum method for excited state preparation that avoids explicitly forming powers of the Hamiltonian or performing variational optimization. We provide a theoretical analysis of success probabilities and resource scaling, and we validate the methods numerically using molecular Hamiltonians. The results show that quantum power Lanczos lowers the computational cost and provides robust convergence compared to naive quantum power iteration. Our findings reveal that GQSP-based implementations of power methods combine scalability, flexibility, and robust convergence, paving the way for practical initial state preparations on fault-tolerant quantum devices.
title Quantum Power Iteration Unified Using Generalized Quantum Signal Processing
topic Quantum Physics
url https://arxiv.org/abs/2507.11142