2026-10-10T02:47:34Z https://api.figshare.com/v2/oai

oai:figshare.com:article/32641485 2026-10-01T16:23:00Z portal_1172 item_type_8 month_year_10_2026

Machine learning-enhanced characterisation of open quantum dynamics Jessica Barr (24170007) PUREID: 647150975 Machine Learning Open Quantum Systems Spectral Density Environment Spectroscopy Neural Network Environment Characterisation Spectral densities encode essential information that characterises the interaction between a system and its environment in an open-quantum system problem. This information is crucial for determining the system's dynamics. In this work, we leverage the potential of machine learning techniques to reconstruct the features of the environment. Specifically, we show that, given the time evolution of a system observable, an artificial neural network can infer the main features of the spectral density.<br><br>Firstly, for relevant examples of exactly solvable and weakly-coupled spin-boson models, we demonstrate that the neural network can classify the Ohmicity parameter of the environment as either Ohmic, sub-Ohmic, or super-Ohmic, with high accuracy, effectively distinguishing between different forms of dissipation. Additionally, we extend our approach to a regression task, where the neural network accurately predicts continuous values of the Ohmicity parameter, the coupling strength and the cut-off frequency, providing a comprehensive characterisation of the spectral density.<br><br>Furthermore, to address scenarios beyond the weak coupling regime, we employ the reaction coordinate mapping. For a dissipative spin-boson model with a structured spectral density comprising one, two, or three Lorentzian peaks, we demonstrate that a neural network can classify the spectral density based on the number of peaks and accurately predict their positions. The methodology developed in this thesis, along with the case studies analysed, demonstrates the effectiveness of machine learning techniques for characterising environments with arbitrary spectral densities across a broad range of coupling regimes. 2026-10-01T16:23:00Z Text Thesis 10.17034/32641485.v1 https://figshare.com/articles/thesis/Machine_learning-enhanced_characterisation_of_open_quantum_dynamics/32641485 All Rights Reserved