HCQA: Hybrid Classical-Quantum Agent for Generating Optimal Quantum Sensor Circuits

Abstract--This study proposes an HCQA for designing optimal Quantum Sensor Circuits (QSCs) to address complex quantum physics problems. The HCQA integrates computational intelligence techniques by leveraging a Deep Q-Network (DQN) for learning and policy optimization, enhanced by a quantum-based action selection mechanism based on the Q-values. Measurement of the circuit results in probabilistic action outcomes, allowing the agent to generate optimal QSCs by selecting sequences of gates that maximize the Quantum Fisher Information (QFI) while minimizing the number of gates. This computational intelligence-driven HCQA enables the automated generation of entangled quantum states, specifically the squeezed states, with high QFI sensitivity for quantum state estimation and control. This work highlights the synergy between AI-driven learning and quantum computation, illustrating how intelligent agents can autonomously discover optimal quantum circuit designs for enhanced sensing and estimation tasks. Impact Statement--The HCQA introduces a hybrid AIquantum framework for generating optimal QSCs, contributing to foundational advances in quantum metrology and intelligent quantum control. By integrating a DQN with quantum-based action selection, the HCQA learns to construct quantum circuits that achieve high QFI with reduced gate complexity. This approach demonstrates how reinforcement learning can guide quantum circuit synthesis in a goal-directed, data-efficient manner. While this work is demonstrated on a simplified two-qubit, noise-free simulation, it provides a proof of concept for how intelligent agents can autonomously learn and optimize QSCs. Technologically, this contributes to the growing field of Quantum Reinforcement Learning (QRL) and supports future exploration of scalable, noise-resilient extensions.