dc.contributorSantos, Francisco Ednilson Alves dos
dc.contributorhttp://lattes.cnpq.br/0500176058863562
dc.contributorhttp://lattes.cnpq.br/2963018707693962
dc.creatorSouza, Renan da Silva
dc.date.accessioned2019-06-03T18:51:07Z
dc.date.accessioned2022-10-10T21:27:45Z
dc.date.available2019-06-03T18:51:07Z
dc.date.available2022-10-10T21:27:45Z
dc.date.created2019-06-03T18:51:07Z
dc.date.issued2019-02-21
dc.identifierSOUZA, Renan da Silva. Effective-action approach to dirty bosons in optical lattices. 2019. Dissertação (Mestrado em Física) – Universidade Federal de São Carlos, São Carlos, 2019. Disponível em: https://repositorio.ufscar.br/handle/ufscar/11449.
dc.identifierhttps://repositorio.ufscar.br/handle/ufscar/11449
dc.identifier.urihttp://repositorioslatinoamericanos.uchile.cl/handle/2250/4041956
dc.description.abstractA system of cold bosonic atoms loaded in an optical lattice potential can undergo a macroscopic phase transition due to quantum fluctuations. As the depth of the lattice potential is increased, the ground state of the many-body system is found to go from a superfluid to a Mott-insulator state. In the presence of disorder a new phase intervenes in these transition: the Bose-glass phase. Usual analysis of this phase transition is made within the framework of mean-field theory. Such approximation predicts non-physical results for the condensate density. Taking into consideration the lack of precise analytical results in the literature, we propose the use of an effective-action approach for investigating such phase transition in the presence of disorder at arbitrary temperatures. These method, based on standard field-theoretical considerations, is used with the aim to improve the results of former analytical methods and provide better qualitative understanding of the quantum phase transition. We considered static diagonal disorder by means of a local chemical potential in the Bose-Hubbard model and obtained the phase boundary for homogeneous and Gaussian disorder distributions. We compared the condensate density predictions of our field theoretical effective-action method with the results of standard mean-field approximation. The application of the effective-action method showed to be promising in analyzing the superfluid to insulating states phase transition in the presence of disorder as well as in improving former analytical results.
dc.languageeng
dc.publisherUniversidade Federal de São Carlos
dc.publisherUFSCar
dc.publisherPrograma de Pós-Graduação em Física - PPGF
dc.publisherCâmpus São Carlos
dc.rightsAcesso aberto
dc.subjectEffective-action
dc.subjectPhase-transition
dc.subjectBose-glass
dc.subjectBose-Hubbard model
dc.subjectBose-Einstein condensation
dc.subjectAção-efetiva
dc.subjectTransição-de-fase
dc.subjectVidro de Bose
dc.subjectModelo-de-Bose-Hubbard
dc.subjectCondensado-de-Bose-Einstein
dc.titleEffective-action approach to dirty bosons in optical lattices
dc.typeTesis


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