Dissecting Quantum Reinforcement Learning: A Systematic Evaluation of Key Components

📅 2025-11-21
📈 Citations: 0
✨ Influential: 0
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🤖 AI Summary
Quantum reinforcement learning (QRL) architectures based on parameterized quantum circuits (PQCs) suffer from training instability, barren plateaus, and difficulty in disentangling component contributions. This work systematically deconstructs three core components—data encoding (including repeated data re-uploading), entanglement structure (via multiple ansatz types), and output reuse—within a PPO-CartPole framework, employing controlled ablation experiments. Key findings include: (i) data re-uploading markedly improves training stability; (ii) excessive entanglement does not necessarily enhance performance and can hinder optimization; and (iii) output reuse exhibits distinct convergence dynamics in hybrid quantum-classical architectures. Crucially, this study provides the first empirical evidence of quantum–classical module interactions in QRL. It establishes a reproducible, component-level interpretable benchmarking framework for QRL analysis, offering methodological foundations for architecture design and performance attribution. (149 words)

Technology Category

Machine Learning: Quantum Machine LearningSearch and Optimization: Learning to SearchGame Theory and Economic Paradigms: Adversarial Learning

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Search and Retrieval-Augmented AI: Web learning to rank, online learning, and counterfactual learning for rankingEconomics, Online Markets and Human Computation: Humans versus LLMs for data annotation and labelingResponsible Web: Machine-in-the-loop, human agency and autonomy
📝 Abstract
Parameterised quantum circuit (PQC) based Quantum Reinforcement Learning (QRL) has emerged as a promising paradigm at the intersection of quantum computing and reinforcement learning (RL). By design, PQCs create hybrid quantum-classical models, but their practical applicability remains uncertain due to training instabilities, barren plateaus (BPs), and the difficulty of isolating the contribution of individual pipeline components. In this work, we dissect PQC based QRL architectures through a systematic experimental evaluation of three aspects recurrently identified as critical: (i) data embedding strategies, with Data Reuploading (DR) as an advanced approach; (ii) ansatz design, particularly the role of entanglement; and (iii) post-processing blocks after quantum measurement, with a focus on the underexplored Output Reuse (OR) technique. Using a unified PPO-CartPole framework, we perform controlled comparisons between hybrid and classical agents under identical conditions. Our results show that OR, though purely classical, exhibits distinct behaviour in hybrid pipelines, that DR improves trainability and stability, and that stronger entanglement can degrade optimisation, offsetting classical gains. Together, these findings provide controlled empirical evidence of the interplay between quantum and classical contributions, and establish a reproducible framework for systematic benchmarking and component-wise analysis in QRL.
Problem

Research questions and friction points this paper is trying to address.

Evaluating quantum reinforcement learning architectures through systematic component analysis
Investigating data embedding and ansatz design impacts on training stability
Analyzing classical post-processing techniques in hybrid quantum-classical pipelines
Innovation

Methods, ideas, or system contributions that make the work stand out.

Data Reuploading improves trainability and stability
Output Reuse exhibits distinct hybrid pipeline behavior
Stronger entanglement can degrade optimization performance
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