Unleashing the Expressive Power of Pulse-Based Quantum Neural Networks

Fuente: arXiv
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Hauptverfasser: Tao, Han-Xiao, Hu, Jiaqi, Wu, Re-Bing
Format: Preprint
Veröffentlicht: 2024
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author Tao, Han-Xiao
Hu, Jiaqi
Wu, Re-Bing
author_facet Tao, Han-Xiao
Hu, Jiaqi
Wu, Re-Bing
contents Quantum machine learning (QML) based on Noisy Intermediate-Scale Quantum (NISQ) devices hinges on the optimal utilization of limited quantum resources. While gate-based QML models are user-friendly for software engineers, their expressivity is restricted by the permissible circuit depth within a finite coherence time. In contrast, pulse-based models enable the construction of "infinitely" deep quantum neural networks within the same time, which may unleash greater expressive power for complex learning tasks. In this paper, this potential is investigated from the perspective of quantum control theory. We first indicate that the nonlinearity of pulse-based models comes from the encoding process that can be viewed as the continuous limit of data-reuploading in gate-based models. Subsequently, we prove that the pulse-based model can approximate arbitrary nonlinear functions when the underlying physical system is ensemble controllable. Under this condition, numerical simulations demonstrate the enhanced expressivity by either increasing the pulse length or the number of qubits. As anticipated, we show through numerical examples that the pulse-based model can unleash more expressive power compared to the gate-based model. These findings lay a theoretical foundation for understanding and designing expressive QML models using NISQ devices.
format Preprint
id arxiv_https___arxiv_org_abs_2402_02880
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Unleashing the Expressive Power of Pulse-Based Quantum Neural Networks
Tao, Han-Xiao
Hu, Jiaqi
Wu, Re-Bing
Quantum Physics
Emerging Technologies
Machine Learning
Quantum machine learning (QML) based on Noisy Intermediate-Scale Quantum (NISQ) devices hinges on the optimal utilization of limited quantum resources. While gate-based QML models are user-friendly for software engineers, their expressivity is restricted by the permissible circuit depth within a finite coherence time. In contrast, pulse-based models enable the construction of "infinitely" deep quantum neural networks within the same time, which may unleash greater expressive power for complex learning tasks. In this paper, this potential is investigated from the perspective of quantum control theory. We first indicate that the nonlinearity of pulse-based models comes from the encoding process that can be viewed as the continuous limit of data-reuploading in gate-based models. Subsequently, we prove that the pulse-based model can approximate arbitrary nonlinear functions when the underlying physical system is ensemble controllable. Under this condition, numerical simulations demonstrate the enhanced expressivity by either increasing the pulse length or the number of qubits. As anticipated, we show through numerical examples that the pulse-based model can unleash more expressive power compared to the gate-based model. These findings lay a theoretical foundation for understanding and designing expressive QML models using NISQ devices.
title Unleashing the Expressive Power of Pulse-Based Quantum Neural Networks
topic Quantum Physics
Emerging Technologies
Machine Learning
url https://arxiv.org/abs/2402.02880