Hierarchical Quantum Control Gates for Functional MRI Understanding
Xuan-Bac Nguyen, Hoang-Quan Nguyen, Hugh Churchill, Samee U. Khan, Khoa Luu
TL;DR
This work tackles understanding extremely high-dimensional fMRI signals, where classical methods struggle with long sequences and voxel-level interactions. It proposes Hierarchical Quantum Control Gates (HQCG), consisting of Local Quantum Control Gates (LQCG) and Global Quantum Control Gates (GQCG), with amplitude encoding to process data on a quantum processor and a multi-class quantum state fidelity circuit for classification. Key contributions include the HQCG architecture, the amplitude-encoded data path, and empirical evidence of improved accuracy and reduced overfitting compared to classical baselines, especially when aggregating information across hemispheres. The results suggest that end-to-end quantum models can effectively learn local and global brain representations from long fMRI sequences and may extend to other domains with ultra-high-dimensional neural data.
Abstract
Quantum computing has emerged as a powerful tool for solving complex problems intractable for classical computers, particularly in popular fields such as cryptography, optimization, and neurocomputing. In this paper, we present a new quantum-based approach named the Hierarchical Quantum Control Gates (HQCG) method for efficient understanding of Functional Magnetic Resonance Imaging (fMRI) data. This approach includes two novel modules: the Local Quantum Control Gate (LQCG) and the Global Quantum Control Gate (GQCG), which are designed to extract local and global features of fMRI signals, respectively. Our method operates end-to-end on a quantum machine, leveraging quantum mechanics to learn patterns within extremely high-dimensional fMRI signals, such as 30,000 samples which is a challenge for classical computers. Empirical results demonstrate that our approach significantly outperforms classical methods. Additionally, we found that the proposed quantum model is more stable and less prone to overfitting than the classical methods.
