Vortices in dilute Bose-Einstein condensates

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dc.contributor Aalto-yliopisto fi
dc.contributor Aalto University en
dc.contributor.author Simula, Tapio
dc.date.accessioned 2011-12-20T10:46:47Z
dc.date.available 2011-12-20T10:46:47Z
dc.date.issued 2003-01-10
dc.identifier.isbn 951-22-6066-2
dc.identifier.issn 1456-3320
dc.identifier.uri https://aaltodoc.aalto.fi/handle/123456789/1216
dc.description.abstract Bose-Einstein condensation, first predicted by Bose and Einstein in 1924, was finally realized in dilute, weakly interacting gases of alkali atoms in 1995. A few years later, quantized vortices - intimately related to the phenomenon of superfluidity - were created and observed in these novel quantum many-body systems. In this Thesis, vortices in dilute atomic Bose-Einstein condensates are studied theoretically and computationally using microscopic mean-field theory formalisms. Special emphasis is on the structure and the stability of vortices at finite temperatures. The formation of quantized circulation in Bose-Einstein condensates is investigated, as well as multiply quantized vorticity and the adiabaticity of the precessing motion of a vortex. This research strongly relies on numerically solving the Gross-Pitaevskii equation for the macroscopic condensate wavefunction and the coupled Bogoliubov equations and their variants for the collective quasiparticle excitation eigenmodes. The computed elementary excitation spectra are used, for instance, in determining the local stability of various condensate states. The vortex formation process is studied at finite temperatures in terms of the surface modes of the condensate providing the Landau critical velocities for the breakdown of superfluidity. Free energy calculations are used for determining the thermodynamic equilibrium states. Singly quantized, axisymmetric vortex states are found to be locally energetically stable even in the zero-temperature limit within the self-consistent finite-temperature approximations. This would imply for the vortex a precession direction opposite to that observed in the experiment. Adiabatic approximation of quantum mechanics is formulated for Bose-Einstein condensed systems and is applied to a case of a moving vortex line. The experimentally observed precessing motion of the vortex is found to be nonadiabatic. A method to create stable multiply quantized vortices using an additional pinning potential is presented. The computed critical trap rotation frequencies for vortex nucleation at finite temperatures are in agreement with experiments and the predictions of zero-temperature field theories. en
dc.format.extent 38, [34]
dc.format.mimetype application/pdf
dc.language.iso en en
dc.publisher Helsinki University of Technology en
dc.publisher Teknillinen korkeakoulu fi
dc.relation.ispartofseries Helsinki University of Technology publications in engineering physics. A en
dc.relation.ispartofseries 813 en
dc.relation.haspart S. M. M. Virtanen, T. P. Simula, and M. M. Salomaa, Structure and Stability of Vortices in Dilute Bose-Einstein Condensates, Physical Review Letters 86, 2704 (2001). © 2001 American Physical Society. By permission.
dc.relation.haspart S. M. M. Virtanen, T. P. Simula, and M. M. Salomaa, Comparison of mean-field theories for vortices in trapped Bose-Einstein condensates, Journal of Physics A: Condensed Matter 12, L819 (2001). [article2.pdf] © 2001 IOP Publishing Ltd. By permission.
dc.relation.haspart S. M. M. Virtanen, T. P. Simula, and M. M. Salomaa, Adiabaticity Criterion for Moving Vortices in Dilute Bose-Einstein Condensates, Physical Review Letters 87, 230403 (2001). © 2001 American Physical Society. By permission.
dc.relation.haspart T. P. Simula, S. M. M. Virtanen, and M. M. Salomaa, Stability of multiquantum vortices in dilute Bose-Einstein condensates, Physical Review A 65, 033614 (2002). © 2002 American Physical Society. By permission.
dc.relation.haspart T. P. Simula, S. M. M. Virtanen, and M. M. Salomaa, Surface modes and vortex formation in dilute Bose-Einstein condensates at finite temperatures, Physical Review A, 66, 035601 (2002). © 2002 American Physical Society. By permission.
dc.relation.haspart T. P. Simula, S. M. M. Virtanen, and M. M. Salomaa, Quantized Circulation in Dilute Bose-Einstein Condensates, Computer Physics Communications 142, 396 (2001). [article6.pdf] © 2001 Elsevier Science. By permission.
dc.subject.other Physics en
dc.title Vortices in dilute Bose-Einstein condensates en
dc.type G5 Artikkeliväitöskirja fi
dc.description.version reviewed en
dc.contributor.department Department of Engineering Physics and Mathematics en
dc.contributor.department Teknillisen fysiikan ja matematiikan osasto fi
dc.subject.keyword Bose-Einstein condensate en
dc.subject.keyword vortex en
dc.subject.keyword superfluidity en
dc.subject.keyword mean-field theory en
dc.subject.keyword quasiparticle en
dc.identifier.urn urn:nbn:fi:tkk-000073
dc.type.dcmitype text en
dc.type.ontasot Väitöskirja (artikkeli) fi
dc.type.ontasot Doctoral dissertation (article-based) en
dc.contributor.lab Materials Physics Laboratory en
dc.contributor.lab Materiaalifysiikan laboratorio fi


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