From Exponential to Quadratic: Optimal Control for a Frustrated Ising Ring Model

Fuente: arXiv
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Autori principali: Wang, Ruiyi, Arezzo, Vincenzo Roberto, Thengil, Kiran, Pecci, Giovanni, Santoro, Giuseppe E.
Natura: Preprint
Pubblicazione: 2025
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author Wang, Ruiyi
Arezzo, Vincenzo Roberto
Thengil, Kiran
Pecci, Giovanni
Santoro, Giuseppe E.
author_facet Wang, Ruiyi
Arezzo, Vincenzo Roberto
Thengil, Kiran
Pecci, Giovanni
Santoro, Giuseppe E.
contents Exponentially small spectral gaps are known to be the crucial bottleneck for traditional Quantum Annealing (QA) based on interpolating between two Hamiltonians, a simple driving term and the complex problem to be solved, with a linear schedule in time. One of the simplest models showing exponentially small spectral gaps was introduced by Roberts et al., PRA 101, 042317 (2020): a ferromagnetic Ising ring with a single frustrating antiferromagnetic bond. A previous study of this model (Côté et al., QST 8, 045033 (2023)) proposed a continuous-time diabatic QA, where optimized non-adiabatic annealing schedules provided good solutions, avoiding exponentially large annealing times. In our work, we move to a digital framework of Variational Quantum Algorithms, and present two main results: 1) we show that the model is digitally controllable with a scaling of resources that grows quadratically with the system size, achieving the exact solution using the Quantum Approximate Optimization Algorithm (QAOA); 2) We combine a technique of quantum control -- the Chopped RAndom Basis (CRAB) method -- and digitized quantum annealing (dQA) to construct smooth digital schedules yielding optimal solutions with very high accuracy.
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id arxiv_https___arxiv_org_abs_2502_17015
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle From Exponential to Quadratic: Optimal Control for a Frustrated Ising Ring Model
Wang, Ruiyi
Arezzo, Vincenzo Roberto
Thengil, Kiran
Pecci, Giovanni
Santoro, Giuseppe E.
Quantum Physics
Exponentially small spectral gaps are known to be the crucial bottleneck for traditional Quantum Annealing (QA) based on interpolating between two Hamiltonians, a simple driving term and the complex problem to be solved, with a linear schedule in time. One of the simplest models showing exponentially small spectral gaps was introduced by Roberts et al., PRA 101, 042317 (2020): a ferromagnetic Ising ring with a single frustrating antiferromagnetic bond. A previous study of this model (Côté et al., QST 8, 045033 (2023)) proposed a continuous-time diabatic QA, where optimized non-adiabatic annealing schedules provided good solutions, avoiding exponentially large annealing times. In our work, we move to a digital framework of Variational Quantum Algorithms, and present two main results: 1) we show that the model is digitally controllable with a scaling of resources that grows quadratically with the system size, achieving the exact solution using the Quantum Approximate Optimization Algorithm (QAOA); 2) We combine a technique of quantum control -- the Chopped RAndom Basis (CRAB) method -- and digitized quantum annealing (dQA) to construct smooth digital schedules yielding optimal solutions with very high accuracy.
title From Exponential to Quadratic: Optimal Control for a Frustrated Ising Ring Model
topic Quantum Physics
url https://arxiv.org/abs/2502.17015