Quantum Policy Iteration via Amplitude Estimation and Grover Search – Towards Quantum Advantage for Reinforcement Learning

Published: 17 Mar 2023, Last Modified: 17 Mar 2023Accepted by TMLREveryoneRevisionsBibTeX
Abstract: We present a full implementation and simulation of a novel quantum reinforcement learning method. Our work is a detailed and formal proof of concept for how quantum algorithms can be used to solve reinforcement learning problems and shows that, given access to error- free, efficient quantum realizations of the agent and environment, quantum methods can yield provable improvements over classical Monte-Carlo based methods in terms of sample complexity. Our approach shows in detail how to combine amplitude estimation and Grover search into a policy evaluation and improvement scheme. We first develop quantum policy evaluation (QPE) which is quadratically more efficient compared to an analogous classi- cal Monte Carlo estimation and is based on a quantum mechanical realization of a finite Markov decision process (MDP). Building on QPE, we derive a quantum policy iteration that repeatedly improves an initial policy using Grover search until the optimum is reached. Finally, we present an implementation of our algorithm for a two-armed bandit MDP which we then simulate.
Submission Length: Regular submission (no more than 12 pages of main content)
Changes Since Last Submission: - Partially rewrote introduction and conclusion (made contributions clearer) - Added background section that introduces most important concepts from quantum computing
Assigned Action Editor: ~Adam_M_White1
License: Creative Commons Attribution 4.0 International (CC BY 4.0)
Submission Number: 591