--- res: bibo_abstract: - In this Thesis, I study composite quantum impurities with variational techniques, both inspired by machine learning as well as fully analytic. I supplement this with exploration of other applications of machine learning, in particular artificial neural networks, in many-body physics. In Chapters 3 and 4, I study quasiparticle systems with variational approach. I derive a Hamiltonian describing the angulon quasiparticle in the presence of a magnetic field. I apply analytic variational treatment to this Hamiltonian. Then, I introduce a variational approach for non-additive systems, based on artificial neural networks. I exemplify this approach on the example of the polaron quasiparticle (Fröhlich Hamiltonian). In Chapter 5, I continue using artificial neural networks, albeit in a different setting. I apply artificial neural networks to detect phases from snapshots of two types physical systems. Namely, I study Monte Carlo snapshots of multilayer classical spin models as well as molecular dynamics maps of colloidal systems. The main type of networks that I use here are convolutional neural networks, known for their applicability to image data.@eng bibo_authorlist: - foaf_Person: foaf_givenName: Wojciech foaf_name: Rzadkowski, Wojciech foaf_surname: Rzadkowski foaf_workInfoHomepage: http://www.librecat.org/personId=48C55298-F248-11E8-B48F-1D18A9856A87 orcid: 0000-0002-1106-4419 bibo_doi: 10.15479/at:ista:10759 dct_date: 2022^xs_gYear dct_isPartOf: - http://id.crossref.org/issn/2663-337X dct_language: eng dct_publisher: Institute of Science and Technology Austria@ dct_title: Analytic and machine learning approaches to composite quantum impurities@ ...