Efficient quantum circuits for machine learning activation functions including constant T-depth ReLU

• Main Authors: Zi, Wei, Wang, Siyi, Kim, Hyunji, Sun, Xiaoming, Chattopadhyay, Anupam, Rebentrost, Patrick
• Other Authors: School of Computer Science and Engineering
• Format: Article
• Language: English
• Published: 2025
• Subjects: Computer and Information Science; Activation functions; Fault-tolerant quantum computing
• Online Access: https://hdl.handle.net/10356/182156
• Institution: Nanyang Technological University

In recent years, Quantum Machine Learning (QML) has increasingly captured the interest of researchers. Among the components in this domain, activation functions hold a fundamental and indispensable role. Our research focuses on the development of activation functions quantum circuits for integration into fault-tolerant quantum computing architectures, with an emphasis on minimizing T-depth. Specifically, we present novel implementations of ReLU and leaky ReLU activation functions, achieving constant T-depths of 4 and 8, respectively. Leveraging quantum lookup tables, we extend our exploration to other activation functions such as the sigmoid. This approach enables us to customize precision and T-depth by adjusting the number of qubits, making our results more adaptable to various application scenarios. This study represents a significant advancement towards enhancing the practicality and application of quantum machine learning.