On the Importance of Fundamental Properties in Quantum-Classical Machine Learning Models

Fuente: arXiv
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Main Authors: Illésová, Silvie, Rybotycki, Tomasz, Gawron, Piotr, Beseda, Martin
Format: Preprint
Published: 2025
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author Illésová, Silvie
Rybotycki, Tomasz
Gawron, Piotr
Beseda, Martin
author_facet Illésová, Silvie
Rybotycki, Tomasz
Gawron, Piotr
Beseda, Martin
contents We present a systematic study of how quantum circuit design, specifically the depth of the variational ansatz and the choice of quantum feature mapping, affects the performance of hybrid quantum-classical neural networks on a causal classification task. The architecture combines a convolutional neural network for classical feature extraction with a parameterized quantum circuit acting as the quantum layer. We evaluate multiple ansatz depths and nine different feature maps. Results show that increasing the number of ansatz repetitions improves generalization and training stability, though benefits tend to plateau beyond a certain depth. The choice of feature mapping is even more critical: only encodings with multi-axis Pauli rotations enable successful learning, while simpler maps lead to underfitting or loss of class separability. Principal Component Analysis and silhouette scores reveal how data distributions evolve across network stages. These findings offer practical guidance for designing quantum circuits in hybrid models. All source codes and evaluation tools are publicly available.
format Preprint
id arxiv_https___arxiv_org_abs_2507_10161
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle On the Importance of Fundamental Properties in Quantum-Classical Machine Learning Models
Illésová, Silvie
Rybotycki, Tomasz
Gawron, Piotr
Beseda, Martin
Quantum Physics
We present a systematic study of how quantum circuit design, specifically the depth of the variational ansatz and the choice of quantum feature mapping, affects the performance of hybrid quantum-classical neural networks on a causal classification task. The architecture combines a convolutional neural network for classical feature extraction with a parameterized quantum circuit acting as the quantum layer. We evaluate multiple ansatz depths and nine different feature maps. Results show that increasing the number of ansatz repetitions improves generalization and training stability, though benefits tend to plateau beyond a certain depth. The choice of feature mapping is even more critical: only encodings with multi-axis Pauli rotations enable successful learning, while simpler maps lead to underfitting or loss of class separability. Principal Component Analysis and silhouette scores reveal how data distributions evolve across network stages. These findings offer practical guidance for designing quantum circuits in hybrid models. All source codes and evaluation tools are publicly available.
title On the Importance of Fundamental Properties in Quantum-Classical Machine Learning Models
topic Quantum Physics
url https://arxiv.org/abs/2507.10161