Hybrid Quantum ResNet for Time Series Classification

Residual networks (ResNet) are known to be effective for image classification. However, challenges such as computational time remain because of the significant number of parameters. Quantum computing using quantum entanglement and quantum parallelism is an emerging computing paradigm that addresses this issue. Although quantum advantage is still studied in many research fields, quantum machine learning is a research area that leverages the strengths of quantum computing and machine learning. In this study, we investigated the quantum speedup with respect to the number of parameters in each model for a time-series classification task. This paper proposes a novel hybrid quantum residual network (HQResNet) inspired by the classical ResNet for time-series classification. HQResNet introduces a classical layer before a quantum convolutional neural network (QCNN), where the QCNN is used as a residual block. These structures enable shortcut connections and are particularly effective in achieving classification tasks without a data re-uploading scheme. We used ultra-wide-band (UWB) channel impulse response data to demonstrate the performance of the proposed algorithm and compared the state-of-the-art benchmarks with HQResNet using evaluation metrics. The results show that HQResNet achieved high performance with a small number of trainable parameters.