Reinforcement Learning Based Actor Critic and Policy Agent for Optimized Quantum Sensor Circuit Design

This paper explores the application of reinforcement learning (RL) algorithms to the domain of quantum sensor circuit design. We focus on the design of four qubits quantum circuits that can efficiently generate states with optimal sensitivity, which maximizes the Quantum Fisher Information (QFI). We formulate the design task as a Markov Decision Process, implementing and comparing two distinct RL strategies: pure policy gradient and actor-critic agents to optimize a Ramsey sequence for maximum QFI. The results demonstrate that both agents are able to find quantum circuit designs with an optimal QFI value of 1. However, the agents differ in the gate sequence of the final Quantum sensor circuit configurations that indicate the optimal state. The policy gradient outperforms the actor-critic method in convergence time and the number of gate sequences for the encoding circuit.