QuEENet: Quantum-Enhanced Expressive Network for Image Classification

This paper presents QuEENet, a hybrid quantum-classical architecture for image classification that incorporates parameterized quantum circuits within a convolutional neural network. This study investigates how quantum circuit expressivity and entanglement strategies influence classification performance, with a focus on configurations involving a CNOT gate followed by a rotational gate on the target qubit. Non-Clifford gates, such as $R_x/R_y/R_z$ supports larger state-space coverage and expressivity in quantum models. The proposed QuEENet explored the aspect of non-Clifford gates in parameterized quantum circuits. While non-Clifford gates are theoretically critical for universal quantum computation, but their role in image classification task is unexplored. Experimental results across multiple benchmark datasets suggest that while increased expressivity via non-Clifford gates can be beneficial, it should be carefully balanced with circuit interpretability and trainability. QuEENet demonstrates that hybrid models can leverage quantum circuits not merely as architectural novelties, but as controllable modules for enhancing learning in classical pipelines. An extensive ablation study was conducted across multiple datasets to highlight the effects of Clifford and non-Clifford gate combinations and entanglement configurations.