Transport and Turbulence in Quasi-Uniform and Versatile Bose-Einstein Condensates PDF
Preview Transport and Turbulence in Quasi-Uniform and Versatile Bose-Einstein Condensates
Springer Theses Recognizing Outstanding Ph.D. Research Gauthier Guillaume Transport and Turbulence in Quasi-Uniform and Versatile Bose-Einstein Condensates Springer Theses Recognizing Outstanding Ph.D. Research Aims and Scope The series “Springer Theses” brings together a selection of the very best Ph.D. theses from around the world and across the physical sciences. Nominated and endorsed by two recognized specialists, each published volume has been selected foritsscientificexcellenceandthehighimpactofitscontentsforthepertinentfield of research. For greater accessibility to non-specialists, the published versions includeanextendedintroduction,aswellasaforewordbythestudent’ssupervisor explainingthespecialrelevanceoftheworkforthefield.Asawhole,theserieswill provide a valuable resource both for newcomers to the research fields described, and for other scientists seeking detailed background information on special questions. Finally, it provides an accredited documentation of the valuable contributions made by today’s younger generation of scientists. Theses are accepted into the series by invited nomination only and must fulfill all of the following criteria (cid:129) They must be written in good English. (cid:129) ThetopicshouldfallwithintheconfinesofChemistry,Physics,EarthSciences, Engineeringandrelatedinterdisciplinary fields such asMaterials,Nanoscience, Chemical Engineering, Complex Systems and Biophysics. (cid:129) The work reported in the thesis must represent a significant scientific advance. (cid:129) Ifthethesisincludespreviouslypublishedmaterial,permissiontoreproducethis must be gained from the respective copyright holder. (cid:129) They must have been examined and passed during the 12 months prior to nomination. (cid:129) Each thesis should include a foreword by the supervisor outlining the signifi- cance of its content. (cid:129) The theses should have a clearly defined structure including an introduction accessible to scientists not expert in that particular field. More information about this series at http://www.springer.com/series/8790 Gauthier Guillaume Transport and Turbulence in Quasi-Uniform and Versatile Bose-Einstein Condensates Doctoral Thesis accepted by The University of Queensland, QLD, Australia 123 Author Supervisor Dr. Gauthier Guillaume Dr. TylerNeely Schoolof Mathematics andPhysics Schoolof Mathematics andPhysics TheUniversity of Queensland TheUniversity of Queensland Brisbane, QLD,Australia Brisbane, QLD,Australia ISSN 2190-5053 ISSN 2190-5061 (electronic) SpringerTheses ISBN978-3-030-54966-4 ISBN978-3-030-54967-1 (eBook) https://doi.org/10.1007/978-3-030-54967-1 ©TheEditor(s)(ifapplicable)andTheAuthor(s),underexclusivelicensetoSpringerNature SwitzerlandAG2020 Thisworkissubjecttocopyright.AllrightsaresolelyandexclusivelylicensedbythePublisher,whether thewholeorpartofthematerialisconcerned,specificallytherightsoftranslation,reprinting,reuseof illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmissionorinformationstorageandretrieval,electronicadaptation,computersoftware,orbysimilar ordissimilarmethodologynowknownorhereafterdeveloped. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publicationdoesnotimply,evenintheabsenceofaspecificstatement,thatsuchnamesareexemptfrom therelevantprotectivelawsandregulationsandthereforefreeforgeneraluse. The publisher, the authors and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, expressed or implied, with respect to the material contained hereinorforanyerrorsoromissionsthatmayhavebeenmade.Thepublisherremainsneutralwithregard tojurisdictionalclaimsinpublishedmapsandinstitutionalaffiliations. ThisSpringerimprintispublishedbytheregisteredcompanySpringerNatureSwitzerlandAG Theregisteredcompanyaddressis:Gewerbestrasse11,6330Cham,Switzerland Dédié à mes parents pour leur amour et leur soutien infaillible au cours des années ’ Supervisor s Foreword Ultracold atoms and Bose-Einstein Condensates (BECs) are nearly ideal experi- mentalsystemsforinvestigatingawidevarietyofcondensedmatterphysics.Some oftheseaspectsarisefromthedilutenatureofthesesystems,suchasthesimplicity of ultracold collisions, for example, but they also arise from the wide variety of refinedexperimentaltechniquesavailabletotheresearcher.Amongthemorerecent advanced techniques, the microscopic control of the BEC density and phase using opticalfieldshasenabledmuchoftherecent experimentalprogressinthefield. Of particular relevance to this thesis, advanced optical control has yielded new experiments in quantum turbulence and new developments in the application- oriented field of atomtronics. Dr. Gauthier’s thesis foremost develops and demonstrates the application of directlyimagedDigitalMicromirrorDevices(DMDs)fortrappingandconfiguring BECs. After first demonstrating the high-resolution DMD pattern projection, trapping, and imaging of BECs, Dr. Gauthier then develops a feed-forward tech- nique permitting engineering of both the density and phase of the BEC. These techniques establish greater control of BECs that will interest readers who seek to enable future cold atoms experiments with finely structured light. Dr. Gauthier appliestheseopticaltrappingtechniquestoinvestigatetwoemergingareasoffocus in superfluid physics: atomtronic oscillators and two-dimensional (2D) quantum turbulence. Atomtronics has emerged as a framework for the building of atom devices analogoustotheirelectricalcounterparts,butwheretheflowofneutralatomstakes the place of charge carriers. Dr. Gauthier’s thesis demonstrates that for lumped atomtronics circuits, such as the dumbbell inductor-capacitor (LC) oscillator investigated,anapproachbasedonacousticsratherthandirectelectronicanalogues can more accurately predict the behaviour of these superfluid circuits. These insights will be important to readers who seek approaches for building superfluid circuit devices, such as inertial sensors. AmongDr.Gauthier’smostsubstantialresultsaretheobservation,70yearsafter its prediction, of the vortex cluster states of 2D turbulence that were predicted by Lars Onsager in 1949. By establishing a uniform quasi-2D condensate, and vii viii Supervisor’sForeword dynamically controlling a DMD to inject vortices, Dr. Gauthier shows that vortex clusters can persist in 2D superfluids for many seconds. These results demonstrate that point-vortex equilibria can be observed in superfluids, and such states are robust even when the entire BEC system is far from equilibrium. In summary, Dr. Gauthier’s thesis will be of interest to a broad range of the SpringerThesisaudience. It will beof interest tothose seekinga technical manual for implementing DMDs and high-resolution optical trapping and imaging of BECs, or those readers seeking to further develop atomtronic technology and sensors based on trapped superfluids. It will be offurther interest for those readers interested in the progress and enabling techniques for the 2D quantum turbulence research that this thesis pioneers. Brisbane, Australia Dr. Tyler Neely June 2020 Abstract Turbulence,motioncharacterizedbychaoticchangesinpressureandflowvelocity, isachallengingprobleminphysics.However,itsunderlyingpropertiesarefoundto beuniversalanddonotdependonthehostfluid.Meanwhile,transportphenomena, irreversible exchange processes due to the statistical continuous random motion of particles, although being complicated from a microscopic point of view, can often be modelled quite simply by tracking macroscopic quantities of interest in the system.Inthisthesis,usingatomicBose-Einsteincondensates,westudyboththese phenomena inside a quantum fluid using a highly configurable BEC platform developed to provide arbitrary dynamic control over the 2D superfluid system. Furthermore,theexperimentsaremodelledusingtheGross-Pitaevskiiequation,the point vortex model and the hydrodynamic equations. Aftertheoreticalbackgroundandintroductiontotheapparatus,thetechniqueof direct imaging of a digital micromirror device is described, which achieves the highly versatile and dynamic 2D potentials that facilitate the experimental studies described. Superfluid transport through a mesoscopic channel of tuneable length and width is next described. By investigating low amplitude oscillations and their dependence on the system parameters, a resistor, capacitor, and inductor model is usedtomodelthetransport.Surprisingly,the“contactinductance”ofthechannelat the reservoirs is a dominant effect for a significant portion of the parameter range. The resistive transport for high initial bias is also studied, where we find turbulent andsounddissipation regimesofenergy dissipationduringthetransport.Next,the transport between two reservoirs initially prepared at different temperatures, but with similar particle number, was explored. Our 2D superfluid system, with hard-wall confinement, provides an ideal experimentalsystemforthestudyof2Dquantumturbulence.Thesystemisutilized todemonstratethefirstexperimentalrealizationoflargeOnsagervortexclustersin the negative absolute temperature regime, through the injection of high energy clusters into the 2D superfluid. The clusters are found to be surprisingly stable for longtimeperiods.Thevortexclusterenergylossrateisstudiedwhilechangingthe system parameters, suggesting thermal damping is the dominant loss mechanism. ix x Abstract Thetechniquesandresultspresented inthis thesis openupnew avenues for the study of quantum fluids, be it by providing a concise atomtronic model for pre- dicting superfluid transport or expanding the accessible parameters space available tofundamentalstudiesofturbulence.Therealizationofnegativetemperaturevortex distributions,longagopredictedbyOnsager,openuptheexperimentalstudyofthe full phase-diagram of 2D vortex matter. The refinement of optical trapping tech- niquesforBECspresentsnewandpromisingdirectionsforfutureBECexperiments in configured potentials.
The list of books you might like
