Hamiltonian and Liouvillian learning in weakly-dissipative quantum many-body systems

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Hauptverfasser: Olsacher, Tobias, Kraft, Tristan, Kokail, Christian, Kraus, Barbara, Zoller, Peter
Format: Preprint
Veröffentlicht: 2024
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author Olsacher, Tobias
Kraft, Tristan
Kokail, Christian
Kraus, Barbara
Zoller, Peter
author_facet Olsacher, Tobias
Kraft, Tristan
Kokail, Christian
Kraus, Barbara
Zoller, Peter
contents We discuss Hamiltonian and Liouvillian learning for analog quantum simulation from non-equilibrium quench dynamics in the limit of weakly dissipative many-body systems. We present and compare various methods and strategies to learn the operator content of the Hamiltonian and the Lindblad operators of the Liouvillian. We compare different ansätze based on an experimentally accessible "learning error" which we consider as a function of the number of runs of the experiment. Initially, the learning error decreases with the inverse square root of the number of runs, as the error in the reconstructed parameters is dominated by shot noise. Eventually the learning error remains constant, allowing us to recognize missing ansatz terms. A central aspect of our approaches is to (re-)parametrize ansätze by introducing and varying the dependencies between parameters. This allows us to identify the relevant parameters of the system, thereby reducing the complexity of the learning task. Importantly, this (re-)parametrization relies solely on classical post-processing, which is compelling given the finite amount of data available from experiments. We illustrate and compare our methods with two experimentally relevant spin models.
format Preprint
id arxiv_https___arxiv_org_abs_2405_06768
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Hamiltonian and Liouvillian learning in weakly-dissipative quantum many-body systems
Olsacher, Tobias
Kraft, Tristan
Kokail, Christian
Kraus, Barbara
Zoller, Peter
Quantum Physics
We discuss Hamiltonian and Liouvillian learning for analog quantum simulation from non-equilibrium quench dynamics in the limit of weakly dissipative many-body systems. We present and compare various methods and strategies to learn the operator content of the Hamiltonian and the Lindblad operators of the Liouvillian. We compare different ansätze based on an experimentally accessible "learning error" which we consider as a function of the number of runs of the experiment. Initially, the learning error decreases with the inverse square root of the number of runs, as the error in the reconstructed parameters is dominated by shot noise. Eventually the learning error remains constant, allowing us to recognize missing ansatz terms. A central aspect of our approaches is to (re-)parametrize ansätze by introducing and varying the dependencies between parameters. This allows us to identify the relevant parameters of the system, thereby reducing the complexity of the learning task. Importantly, this (re-)parametrization relies solely on classical post-processing, which is compelling given the finite amount of data available from experiments. We illustrate and compare our methods with two experimentally relevant spin models.
title Hamiltonian and Liouvillian learning in weakly-dissipative quantum many-body systems
topic Quantum Physics
url https://arxiv.org/abs/2405.06768