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dc.contributor.advisorBlakie, Blair
dc.contributor.advisorBaillie, Danny
dc.contributor.advisorBradley, Ashton
dc.contributor.authorSymes, Luke
dc.date.available2019-02-27T20:21:42Z
dc.date.copyright2019
dc.identifier.citationSymes, L. (2019). Exact nonlinear dynamics of Spinor BECs applied to nematic quenches (Thesis, Doctor of Philosophy). University of Otago. Retrieved from http://hdl.handle.net/10523/9006en
dc.identifier.urihttp://hdl.handle.net/10523/9006
dc.description.abstractIn this thesis we study the nonlinear dynamics of spin-1 and spin-2 Bose-Einstein condensates, with particular application to antiferromagnetic systems exhibiting nematic (beyond magnetic) order. Firstly, we give a derivation of the spinor energy functionals with a focus on the connections between the nonlinear terms. We derive a hierarchy of nonlinear irreducible multipole observables sensitive to different levels of nematic order, and explore the various nematic states in terms of their multipolar order, representations of their symmetries, and topological defects. We then develop an exact solution to the nonlinear dynamics of spinor Bose-Einstein condensates. We use this solution to construct efficient and accurate numerical algorithms to evolve the spinor Gross-Pitaevskii equation in time. We demonstrate the advantages of our algorithms with several 1D numerical test problems, comparing with existing methods in the literature. We apply our numerical methods to simulating quenches of the condensate between various antiferromagnetic phases for spin-1 and spin-2. For spin-1, we carry out quenches for a theoretical uniform system in 2D, and then specialize to the parameters used in a recent harmonically trapped experiment in 3D. We connect the long-time coarsening growth law of the relevant order parameter to the decay of half-quantum vortices, which are the relevant topological defects of the ground state. For the spin-2 system, we investigate a novel quench from two different quadrupolar-nematic phases to an octupolar-nematic “cyclic” phase which supports 1/3 fractional vortices. We develop appropriate order parameter observables which couple to the spin and superfluid currents generated by these defects, and show that a new growth law appears with exponent 1/3.
dc.format.mimetypeapplication/pdf
dc.format.mimetypeapplication/zip
dc.language.isoen
dc.publisherUniversity of Otago
dc.rightsAll items in OUR Archive are provided for private study and research purposes and are protected by copyright with all rights reserved unless otherwise indicated.
dc.subjectBose-einstein condensates
dc.subjectSpinor
dc.subjectBEC
dc.subjectnonlinear dynamics
dc.subjectantiferromagnetic
dc.subjectmagnetization
dc.subjectnematic order
dc.subjectspin
dc.subjectcondensate
dc.subjectmulticomponent
dc.subjectGross-Pitaevskii
dc.subjectnonlinear Schrödinger equation
dc.subjectquench
dc.subjectcoarsening
dc.subjectphase ordering
dc.subjectsymplectic
dc.subjectnematic tensor
dc.subjectquadrupole
dc.subjectoctupole
dc.subjectvortices
dc.subjecttopological defect
dc.subjecthalf-quantum vortex
dc.subjectcyclic vortex
dc.subjectorder parameter
dc.subjectgrowth law
dc.titleExact nonlinear dynamics of Spinor BECs applied to nematic quenches
dc.typeThesis
dc.date.updated2019-02-27T06:32:20Z
dc.language.rfc3066en
thesis.degree.disciplinePhysics
thesis.degree.nameDoctor of Philosophy
thesis.degree.grantorUniversity of Otago
thesis.degree.levelDoctoral
otago.openaccessOpen
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