Quantum Many-body Simulations from a Reinforcement-Learned Exponential Ansatz

Fuente: arXiv
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Autores principales: Wang, Yuchen, Mazziotti, David A.
Formato: Preprint
Publicado: 2025
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author Wang, Yuchen
Mazziotti, David A.
author_facet Wang, Yuchen
Mazziotti, David A.
contents Solving for the many-body wavefunction represents a significant challenge on both classical and quantum devices because of the exponential scaling of the Hilbert space with system size. While the complexity of the wavefunction can be reduced through conventional ansätze (e.g., the coupled cluster ansatz), it can still grow rapidly with system size even on quantum devices. An exact, universal two-body exponential ansatz for the many-body wavefunction has been shown to be generated from the solution of the contracted Schrödinger equation (CSE), and recently, this ansatz has been implemented without classical approximation on quantum simulators and devices for the scalable simulation of many-body quantum systems. Here we combine the solution of the CSE with a form of artificial intelligence known as reinforcement learning (RL) to generate highly compact circuits that implement this ansatz without sacrificing accuracy. As a natural extension of CSE, we reformulate the wavefunction update as a Markovian decision process and train the agent to select the optimal actions at each iteration based upon only the current CSE residual. Compact circuits with high accuracy are achieved for H3 and H4 molecules over a range of molecular geometries.
format Preprint
id arxiv_https___arxiv_org_abs_2505_01935
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Quantum Many-body Simulations from a Reinforcement-Learned Exponential Ansatz
Wang, Yuchen
Mazziotti, David A.
Quantum Physics
Chemical Physics
Computational Physics
Solving for the many-body wavefunction represents a significant challenge on both classical and quantum devices because of the exponential scaling of the Hilbert space with system size. While the complexity of the wavefunction can be reduced through conventional ansätze (e.g., the coupled cluster ansatz), it can still grow rapidly with system size even on quantum devices. An exact, universal two-body exponential ansatz for the many-body wavefunction has been shown to be generated from the solution of the contracted Schrödinger equation (CSE), and recently, this ansatz has been implemented without classical approximation on quantum simulators and devices for the scalable simulation of many-body quantum systems. Here we combine the solution of the CSE with a form of artificial intelligence known as reinforcement learning (RL) to generate highly compact circuits that implement this ansatz without sacrificing accuracy. As a natural extension of CSE, we reformulate the wavefunction update as a Markovian decision process and train the agent to select the optimal actions at each iteration based upon only the current CSE residual. Compact circuits with high accuracy are achieved for H3 and H4 molecules over a range of molecular geometries.
title Quantum Many-body Simulations from a Reinforcement-Learned Exponential Ansatz
topic Quantum Physics
Chemical Physics
Computational Physics
url https://arxiv.org/abs/2505.01935