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Hybrid Quantum-Classical Mixture of Experts: Unlocking Topological Advantage via Interference-Based Routing

Reda Heddad, Lamiae Bouanane

TL;DR

This work addresses the bottlenecks of classical mixture-of-experts routing by introducing a Hybrid Quantum MoE with a Quantum Router. It validates the Interference Hypothesis, showing that quantum routing can model complex decision boundaries with higher parameter efficiency and robustness on non-linear data, as demonstrated on the Two Moons dataset and other benchmarks. Through an ablation study, it isolates the quantum router as the primary source of quantum advantage, while offering practical pathways for NISQ-era deployment and applications in privacy-preserving federated learning, adaptive systems, and edge computing. The paper also outlines limitations and future directions, including hardware validation, fully quantum experts, and formal expressivity analyses, highlighting the potential for quantum routing to impact scalable, efficient intelligent systems.

Abstract

The Mixture-of-Experts (MoE) architecture has emerged as a powerful paradigm for scaling deep learning models, yet it is fundamentally limited by challenges such as expert imbalance and the computational complexity of classical routing mechanisms. This paper investigates the potential of Quantum Machine Learning (QML) to address these limitations through a novel Hybrid Quantum-Classical Mixture of Experts (QMoE) architecture. Specifically, we conduct an ablation study using a Quantum Gating Network (Router) combined with classical experts to isolate the source of quantum advantage. Our central finding validates the Interference Hypothesis: by leveraging quantum feature maps (Angle Embedding) and wave interference, the Quantum Router acts as a high-dimensional kernel method, enabling the modeling of complex, non-linear decision boundaries with superior parameter efficiency compared to its classical counterparts. Experimental results on non-linearly separable data, such as the Two Moons dataset, demonstrate that the Quantum Router achieves a significant topological advantage, effectively "untangling" data distributions that linear classical routers fail to separate efficiently. Furthermore, we analyze the architecture's robustness against simulated quantum noise, confirming its feasibility for near-term intermediate-scale quantum (NISQ) hardware. We discuss practical applications in federated learning, privacy-preserving machine learning, and adaptive systems that could benefit from this quantum-enhanced routing paradigm.

Hybrid Quantum-Classical Mixture of Experts: Unlocking Topological Advantage via Interference-Based Routing

TL;DR

This work addresses the bottlenecks of classical mixture-of-experts routing by introducing a Hybrid Quantum MoE with a Quantum Router. It validates the Interference Hypothesis, showing that quantum routing can model complex decision boundaries with higher parameter efficiency and robustness on non-linear data, as demonstrated on the Two Moons dataset and other benchmarks. Through an ablation study, it isolates the quantum router as the primary source of quantum advantage, while offering practical pathways for NISQ-era deployment and applications in privacy-preserving federated learning, adaptive systems, and edge computing. The paper also outlines limitations and future directions, including hardware validation, fully quantum experts, and formal expressivity analyses, highlighting the potential for quantum routing to impact scalable, efficient intelligent systems.

Abstract

The Mixture-of-Experts (MoE) architecture has emerged as a powerful paradigm for scaling deep learning models, yet it is fundamentally limited by challenges such as expert imbalance and the computational complexity of classical routing mechanisms. This paper investigates the potential of Quantum Machine Learning (QML) to address these limitations through a novel Hybrid Quantum-Classical Mixture of Experts (QMoE) architecture. Specifically, we conduct an ablation study using a Quantum Gating Network (Router) combined with classical experts to isolate the source of quantum advantage. Our central finding validates the Interference Hypothesis: by leveraging quantum feature maps (Angle Embedding) and wave interference, the Quantum Router acts as a high-dimensional kernel method, enabling the modeling of complex, non-linear decision boundaries with superior parameter efficiency compared to its classical counterparts. Experimental results on non-linearly separable data, such as the Two Moons dataset, demonstrate that the Quantum Router achieves a significant topological advantage, effectively "untangling" data distributions that linear classical routers fail to separate efficiently. Furthermore, we analyze the architecture's robustness against simulated quantum noise, confirming its feasibility for near-term intermediate-scale quantum (NISQ) hardware. We discuss practical applications in federated learning, privacy-preserving machine learning, and adaptive systems that could benefit from this quantum-enhanced routing paradigm.
Paper Structure (48 sections, 8 equations, 3 figures, 2 tables)

This paper contains 48 sections, 8 equations, 3 figures, 2 tables.

Figures (3)

  • Figure 1: Decision boundary comparison on Two Moons dataset showing quantum router's ability to create smooth non-linear separation compared to classical linear router.
  • Figure 2: Parameter efficiency comparison showing accuracy vs. number of trainable parameters across different architectures. The quantum router achieves higher accuracy with significantly fewer parameters.
  • Figure 3: Training dynamics showing loss and accuracy curves during the optimization process. The quantum router demonstrates stable convergence.