Quantum equilibrium propagation for efficient training of quantum systems based on Onsager reciprocity

Abstract The widespread adoption of machine learning and artificial intelligence in all branches of science and technology creates a need for energy-efficient, alternative hardware. While such neuromorphic systems have been demonstrated in a wide range of platforms, it remains an open challenge to f...

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Main Authors: Clara C. Wanjura, Florian Marquardt
Format: Article
Language:English
Published: Nature Portfolio 2025-07-01
Series:Nature Communications
Online Access:https://doi.org/10.1038/s41467-025-61665-6
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author Clara C. Wanjura
Florian Marquardt
author_facet Clara C. Wanjura
Florian Marquardt
author_sort Clara C. Wanjura
collection DOAJ
description Abstract The widespread adoption of machine learning and artificial intelligence in all branches of science and technology creates a need for energy-efficient, alternative hardware. While such neuromorphic systems have been demonstrated in a wide range of platforms, it remains an open challenge to find efficient and general physics-based training approaches. Equilibrium propagation (EP), the most widely studied approach, has been introduced for classical energy-based models relaxing to an equilibrium. Here, we show a direct connection between EP and Onsager reciprocity and exploit this to derive a quantum version of EP. For an arbitrary quantum system, this can now be used to extract training gradients with respect to all tuneable parameters via a single linear response experiment. We illustrate this new concept in examples in which the input or the task is of quantum-mechanical nature, e.g., the recognition of many-body ground states, phase discovery, sensing, and phase boundary exploration. Quantum EP may be used to solve challenges such as quantum phase discovery for Hamiltonians which are classically hard to simulate or even partially unknown. Our scheme is relevant for a variety of quantum simulation platforms such as ion chains, superconducting circuits, Rydberg atom tweezer arrays and ultracold atoms in optical lattices.
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spelling doaj-art-df5d4d3e775541229008e697b26a197d2025-08-20T04:02:55ZengNature PortfolioNature Communications2041-17232025-07-0116111110.1038/s41467-025-61665-6Quantum equilibrium propagation for efficient training of quantum systems based on Onsager reciprocityClara C. Wanjura0Florian Marquardt1Max Planck Institute for the Science of LightMax Planck Institute for the Science of LightAbstract The widespread adoption of machine learning and artificial intelligence in all branches of science and technology creates a need for energy-efficient, alternative hardware. While such neuromorphic systems have been demonstrated in a wide range of platforms, it remains an open challenge to find efficient and general physics-based training approaches. Equilibrium propagation (EP), the most widely studied approach, has been introduced for classical energy-based models relaxing to an equilibrium. Here, we show a direct connection between EP and Onsager reciprocity and exploit this to derive a quantum version of EP. For an arbitrary quantum system, this can now be used to extract training gradients with respect to all tuneable parameters via a single linear response experiment. We illustrate this new concept in examples in which the input or the task is of quantum-mechanical nature, e.g., the recognition of many-body ground states, phase discovery, sensing, and phase boundary exploration. Quantum EP may be used to solve challenges such as quantum phase discovery for Hamiltonians which are classically hard to simulate or even partially unknown. Our scheme is relevant for a variety of quantum simulation platforms such as ion chains, superconducting circuits, Rydberg atom tweezer arrays and ultracold atoms in optical lattices.https://doi.org/10.1038/s41467-025-61665-6
spellingShingle Clara C. Wanjura
Florian Marquardt
Quantum equilibrium propagation for efficient training of quantum systems based on Onsager reciprocity
Nature Communications
title Quantum equilibrium propagation for efficient training of quantum systems based on Onsager reciprocity
title_full Quantum equilibrium propagation for efficient training of quantum systems based on Onsager reciprocity
title_fullStr Quantum equilibrium propagation for efficient training of quantum systems based on Onsager reciprocity
title_full_unstemmed Quantum equilibrium propagation for efficient training of quantum systems based on Onsager reciprocity
title_short Quantum equilibrium propagation for efficient training of quantum systems based on Onsager reciprocity
title_sort quantum equilibrium propagation for efficient training of quantum systems based on onsager reciprocity
url https://doi.org/10.1038/s41467-025-61665-6
work_keys_str_mv AT claracwanjura quantumequilibriumpropagationforefficienttrainingofquantumsystemsbasedononsagerreciprocity
AT florianmarquardt quantumequilibriumpropagationforefficienttrainingofquantumsystemsbasedononsagerreciprocity