Hierarchical Fusion Method for Scalable Quantum Eigenstate Preparation

Fuente: arXiv
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Auteurs principaux: Patkowski, Matthew, Ayyildiz, Onat, Kebrič, Matjaž, Hunt, Katharine L. C., Lee, Dean
Format: Preprint
Publié: 2025
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author Patkowski, Matthew
Ayyildiz, Onat
Kebrič, Matjaž
Hunt, Katharine L. C.
Lee, Dean
author_facet Patkowski, Matthew
Ayyildiz, Onat
Kebrič, Matjaž
Hunt, Katharine L. C.
Lee, Dean
contents Robust and efficient eigenstate preparation is a central challenge in quantum simulation. The Rodeo Algorithm (RA) offers exponential convergence to a target eigenstate but suffers from poor performance when the initial state has low overlap with the desired eigenstate, hindering the applicability of the original algorithm to larger systems. In this work, we introduce a fusion method that preconditions the RA state by an adiabatic ramp to overcome this limitation. By incrementally building up large systems from exactly solvable subsystems and using adiabatic preconditioning to enhance intermediate state overlaps, we ensure that the RA retains its exponential convergence even in large-scale systems. We demonstrate this hybrid approach using numerical simulations of the spin- 1/2 XX model and find that the Rodeo Algorithm exhibits robust exponential convergence across system sizes. We benchmark against using only an adiabatic ramp as well as using the unmodified RA, finding that for state preparation precision at the level of $10^{-3}$ infidelity or better there a decisive computational cost advantage to the fusion method. These results together demonstrate the scalability and effectiveness of the fusion method for practical quantum simulations.
format Preprint
id arxiv_https___arxiv_org_abs_2510_19039
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Hierarchical Fusion Method for Scalable Quantum Eigenstate Preparation
Patkowski, Matthew
Ayyildiz, Onat
Kebrič, Matjaž
Hunt, Katharine L. C.
Lee, Dean
Quantum Physics
Robust and efficient eigenstate preparation is a central challenge in quantum simulation. The Rodeo Algorithm (RA) offers exponential convergence to a target eigenstate but suffers from poor performance when the initial state has low overlap with the desired eigenstate, hindering the applicability of the original algorithm to larger systems. In this work, we introduce a fusion method that preconditions the RA state by an adiabatic ramp to overcome this limitation. By incrementally building up large systems from exactly solvable subsystems and using adiabatic preconditioning to enhance intermediate state overlaps, we ensure that the RA retains its exponential convergence even in large-scale systems. We demonstrate this hybrid approach using numerical simulations of the spin- 1/2 XX model and find that the Rodeo Algorithm exhibits robust exponential convergence across system sizes. We benchmark against using only an adiabatic ramp as well as using the unmodified RA, finding that for state preparation precision at the level of $10^{-3}$ infidelity or better there a decisive computational cost advantage to the fusion method. These results together demonstrate the scalability and effectiveness of the fusion method for practical quantum simulations.
title Hierarchical Fusion Method for Scalable Quantum Eigenstate Preparation
topic Quantum Physics
url https://arxiv.org/abs/2510.19039