Estimates of loss function concentration in noisy parametrized quantum circuits

Fuente: arXiv
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Autores principales: Crognaletti, Giulio, Grossi, Michele, Bassi, Angelo
Formato: Preprint
Publicado: 2024
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author Crognaletti, Giulio
Grossi, Michele
Bassi, Angelo
author_facet Crognaletti, Giulio
Grossi, Michele
Bassi, Angelo
contents Variational quantum computing offers a powerful framework with applications across diverse fields such as quantum chemistry, machine learning, and optimization. However, its scalability is hindered by the exponential concentration of the loss function, known as the barren plateau problem. While significant progress has been made and prior work has separately analyzed barren plateaus in unitary and noisy settings, their combined impact remains poorly understood, largely due to limitations in conventional Lie-algebraic approaches. In this work, we introduce a novel analytical framework based on non-negative matrix theory that enables the description of the variance in layered noisy quantum circuits with arbitrary noise channels. This approach enables the derivation of exact expressions in the deep-circuit regime, uncovering the complex interplay between unitary layers and noise. Notably, we identify a noise-induced absorption mechanism-a phenomenon absent in purely unitary dynamics-which provides new insight into how noise shapes circuit behavior. We further present a controlled convergence analysis, establishing general lower bounds on the variance of both deep and shallow circuits. This leads to a principled connection between noise resilience and the expressive capacity of parameterized quantum circuits, particularly under smart initialization strategies. Our theoretical results are supported by numerical simulations and illustrative applications.
format Preprint
id arxiv_https___arxiv_org_abs_2410_01893
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Estimates of loss function concentration in noisy parametrized quantum circuits
Crognaletti, Giulio
Grossi, Michele
Bassi, Angelo
Quantum Physics
Variational quantum computing offers a powerful framework with applications across diverse fields such as quantum chemistry, machine learning, and optimization. However, its scalability is hindered by the exponential concentration of the loss function, known as the barren plateau problem. While significant progress has been made and prior work has separately analyzed barren plateaus in unitary and noisy settings, their combined impact remains poorly understood, largely due to limitations in conventional Lie-algebraic approaches. In this work, we introduce a novel analytical framework based on non-negative matrix theory that enables the description of the variance in layered noisy quantum circuits with arbitrary noise channels. This approach enables the derivation of exact expressions in the deep-circuit regime, uncovering the complex interplay between unitary layers and noise. Notably, we identify a noise-induced absorption mechanism-a phenomenon absent in purely unitary dynamics-which provides new insight into how noise shapes circuit behavior. We further present a controlled convergence analysis, establishing general lower bounds on the variance of both deep and shallow circuits. This leads to a principled connection between noise resilience and the expressive capacity of parameterized quantum circuits, particularly under smart initialization strategies. Our theoretical results are supported by numerical simulations and illustrative applications.
title Estimates of loss function concentration in noisy parametrized quantum circuits
topic Quantum Physics
url https://arxiv.org/abs/2410.01893