Scalability Challenges in Variational Quantum Optimization under Stochastic Noise

Fuente: arXiv
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Main Authors: Bärligea, Adelina, Poggel, Benedikt, Lorenz, Jeanette Miriam
Format: Preprint
Published: 2025
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author Bärligea, Adelina
Poggel, Benedikt
Lorenz, Jeanette Miriam
author_facet Bärligea, Adelina
Poggel, Benedikt
Lorenz, Jeanette Miriam
contents With rapid advances in quantum hardware, a central question is whether quantum devices with or without full error correction can outperform classical computers on practically relevant problems. Variational Quantum Algorithms (VQAs) have gained significant attention as promising candidates in this pursuit, particularly for combinatorial optimization problems. While reports of their challenges and limitations continue to accumulate, many studies remain optimistic based on small-scale, idealized testing setups, leaving doubt about the scalability of VQAs for large-scale problems. We systematically investigate this scaling behavior by analyzing how classical optimizers minimize variational quantum loss functions for random QUBO instances in the presence of uncertainty, modeled as effective Gaussian noise. We find that the critical noise threshold for successful optimization decreases rapidly as system size grows. This decline exceeds what can be explained solely by shrinking loss variance, confirming deeper, fundamental limitations in the loss landscapes of VQAs beyond barren plateaus. Translating these thresholds into required measurement shots reveals that achieving sufficient precision in the evaluated loss values quickly becomes impractical, even for moderately-sized problems. Our findings demonstrate serious scalability challenges for VQAs in optimization stemming from mere uncertainty, indicating potential barriers to achieving practical quantum advantage with current hybrid approaches.
format Preprint
id arxiv_https___arxiv_org_abs_2503_14696
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Scalability Challenges in Variational Quantum Optimization under Stochastic Noise
Bärligea, Adelina
Poggel, Benedikt
Lorenz, Jeanette Miriam
Quantum Physics
68Q12, 90C59, 90C27, 81P68
F.2; G.1.6; G.3; F.1.2
With rapid advances in quantum hardware, a central question is whether quantum devices with or without full error correction can outperform classical computers on practically relevant problems. Variational Quantum Algorithms (VQAs) have gained significant attention as promising candidates in this pursuit, particularly for combinatorial optimization problems. While reports of their challenges and limitations continue to accumulate, many studies remain optimistic based on small-scale, idealized testing setups, leaving doubt about the scalability of VQAs for large-scale problems. We systematically investigate this scaling behavior by analyzing how classical optimizers minimize variational quantum loss functions for random QUBO instances in the presence of uncertainty, modeled as effective Gaussian noise. We find that the critical noise threshold for successful optimization decreases rapidly as system size grows. This decline exceeds what can be explained solely by shrinking loss variance, confirming deeper, fundamental limitations in the loss landscapes of VQAs beyond barren plateaus. Translating these thresholds into required measurement shots reveals that achieving sufficient precision in the evaluated loss values quickly becomes impractical, even for moderately-sized problems. Our findings demonstrate serious scalability challenges for VQAs in optimization stemming from mere uncertainty, indicating potential barriers to achieving practical quantum advantage with current hybrid approaches.
title Scalability Challenges in Variational Quantum Optimization under Stochastic Noise
topic Quantum Physics
68Q12, 90C59, 90C27, 81P68
F.2; G.1.6; G.3; F.1.2
url https://arxiv.org/abs/2503.14696