Contents - Max-Planck-Institut für Physik komplexer Systeme
Contents - Max-Planck-Institut für Physik komplexer Systeme
Contents - Max-Planck-Institut für Physik komplexer Systeme
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ResearchGroup:ComplexDynamicsinColdGases<br />
(Head:Dr.T.Pohl)<br />
ThegroupwasestablishedinSeptember2008,andcurrentlyhoststhreePhDstudents(GeorgBannasch,<br />
NilsHenkel,RickMukherjee)andtwopostdoctoralguestscientists(SevilaySevinçli,RejishNath).Our<br />
researchiscenteredaroundthebehaviorofcoldandultracoldatomicgases.Inparticular,weareinterestedintheirresponsetolaserradiation,whichmaycausecorrelated,many-bodydynamicstoemerge<br />
directlyasatomsareionizedorexcitedtohighlyingstates. Asoutlinedbelow,theunderstandingof<br />
thisprocessandtheback-and-forthinteractionbetweenlightandcorrelatedmatterraisesratherdiverse<br />
questions,andopensuppromisingavenuesforapplicationsinopticalandinformationscience.<br />
Ultracoldplasmas,formedbyphotoionizationoflaser-cooledatoms,occupyanexoticparameterregime<br />
ofplasmaphysicsinwhichthepotentialenergygreatlyexceedsthethermalenergyofthecharges.Such<br />
plasmasarecreatedfarfromequilibrium,and,thus,provideanidealplatformtostudynon-equilibrium<br />
phenomenainstronglycorrelatedCoulombsystems.Wehavedevelopedefficientmicroscopicapproaches<br />
tostudyatomicreactions,relaxationprocessesandcollectivephenomenaundersuchstrongcouplingconditions.Furtherweareexploringtheutilityoflaserlighttoprobeandevencontroltheplasmadynamics.<br />
Partsofthisworkisbeingdoneinajointtheoretical-experimentaleffortwiththegroupofProf. T.C.<br />
KillianatRiceUniversity,USA.<br />
BoseEinsteincondensatesoflong-rangeinteractingparticlesareanotherfocusofourresearchactivities.<br />
Recently,weconsideredoff-resonantlasercouplingtohigh-lyingRydbergstatesasameansofovercomingthelifetime-limitationsetbyexcitedstatedecay.<br />
Atthesametime,sucha”Rydberg-dressing”<br />
producesapeculiareffectiveinteraction,featuringlong-rangetailsandasoftcoreatsmalldistances,<br />
whichpreventscondensatecollapse,asotherwiseoccurringdipolarcondensates. Wehaveshownthat<br />
thisapproachprovidesapromisingphysicalsettingtorealizeacontinuoussupersolidstateinultracold<br />
atomsandallowstocreateentirelyself-trappedstructures,i.e.three-dimensionalbrightsolitons,forthe<br />
firsttimeinBoseEinsteincondensates.Whiletheseresultsarelargelybasedonamean-fielddescription,<br />
werecentlystartedtoexploreeffectsofthermalandquantumfluctuations,withinacollaborationwith<br />
thegroupofProf.PeterZoller(InnsbruckUniversity).Futurework,willaddresscollectiveinteractions,<br />
arisingfromhigher-ordercorrelationsbetweendressedexcitations,androtatingsystems,whichsuggest<br />
aninterestingcompetitionbetweensupersolidorderingandtheemergingAbrikhosov-latticeofvortices<br />
duetotherotation.<br />
Opticallattices,filledwithultracoldatoms,havebecomearemarkablyversatiletoolboxtoaddressfundamentalcondensedmatterphysicsproblems.AparadigmexampleareHubbard-typemodels,whereatoms<br />
tunnelbetweenadjacentlatticesitesandfeaturelocalonsiteinteractions. Inanefforttoextendsuch<br />
settingstolong-rangeinteractingsystems,wehaveworkedoutaschemeforstrongmagic-wavelength<br />
trappingofground-andRydberg-states,thatexploitstheavailabilityoftwovalenceelectronsinalkalineearthatoms.<br />
Thiscombinationoftightlatticeconfinementandstrongstate-dependentinteractions,<br />
forexample,providesanessentialpre-requisiteforimplementationsofdigitalquantumsimulatorsand<br />
scalablequantumcomputers. Amongnextsteps,wecurrentlystudyanovelapproachforcontrolled<br />
Rydberg-state-enabledchargetransportinsuchanalkaline-earthlatticeandexploresuitable,robustprotocolsforthegenerationofnon-classicalmany-bodystatesinStrontiumRydberg-atomlattices,which<br />
mayprovideanentanglement-resourceforapplicationsinhigh-precisionfrequencymetrology.<br />
Nonlinearopticsiscommonlybasedonhigherorderlight-matterinteractions,suchthattheresulting<br />
nonlinearitiesareoftenofperturbativenature.Inthisrespect,thecombinationofslow-lighttechniques<br />
andstronglyinteractingRydbergstatesinanultracoldgaspromisesnewperspectivesforthefield,which,<br />
onlyrecently,haveattractedincreasedexperimentalandtheoreticalinterest. Inthepastfewyears,we<br />
havedevelopedcomplementarynumericalmethodsaswellasanalyticalapproachesthatallowtostudy<br />
thisproblem. Ourcalculationsprovideanexcellentdescriptionofrecentexperimentsandrevealauniversalscalingrelationthatilluminatestheoriginoftheopticalnonlinearities,emergingfromthehighly<br />
correlatedlight-drivengasdynamics.Wepredictgiantnonlinearsusceptibilitiesthataremanyordersof<br />
magnitudelargerthanrealizedinotheropticalmedia,whichcouldmakeseveralapplications,suchas<br />
few-photonopticalswitches,possible.Havingestablishedatheoryfortheopticalresponseofanultracold<br />
12 ScientificWorkanditsOrganizationatthe<strong>Institut</strong>e–anOverview
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