Teleportation breakthrough paves the way for quantum internet

As Hanson explains: “The key feature of quantum teleportation is that the quantum information itself is actually teleported: it does not travel ... RaúlLimón26May2022-15:39UTCWhatsappFacebookTwitterCopylinkQuTechresearchersworkononeofthequantumnetwork’snodes,wheremirrorsandfiltersguidelaserbeamsontothediamondchip.MariekedeLorijnQuantumcomputingisadvancinginbothtinyandgiantsteps.Tiny,becausewhatisachievedinvolvesuniquebreakthroughsoflimitations;giant,becauseeachstrideopensupaworldofinfinitepossibilities.OnesuchstephasbeentakenbyaresearchteamledbyRonaldHanson,aphysicistattheQuTechlaboratoryatDelftUniversityintheNetherlands,whichhassucceededinteleportingquantuminformationviaarudimentarynetworkwithnodirectconnectionbetweensenderandreceiver.Thisquantumleap,publishedWednesdayinNature,meansweareonestepclosertoaquantuminternetwhichwouldthenleadtoanentirelynewkindofcomputerthatcouldcarryouttasksthatwouldtakesupercomputersthousandsofyearsinamatterofminutes,pavingthewayforhugeprogressintherealmsofmedicineandartificialintelligence.Basicteleportationhadalreadybeenachieved–Hanson’steamandothershavealreadydemonstratedit–butonlybetweentwopoints,oradjacentnodes,namedAliceandBob.Now,Hanson’steamhavemanagedtolinkthispairatadistancewithathird,Charlie.Thetrioformthefirstnetworkthat,althoughrudimentary,allowsustocontemplateaquantuminternet,withinfinitepossibilitiesforcomputationandforobservingahithertounknownworld.Explainingtherelevanceofthisprimordialquantumnetwork,Hansonsays:“Regardingquantumcommunication,ourworkshowshowteleportationcanbeusedinarealnetworkenvironment,withnodesthathavenodirectconnection.Inafuturequantuminternet,suchteleportationwillbethemainwaytotransferquantuminformationoverlargedistances.Ournetworkcanbeviewedasamodularquantumcomputer[wherethenodesarethemodules];ourworkshowsthatnodescanexchangequantuminformation,eveniftheyarenotonasinglechip.”TounderstandtheprogressmadebyHanson’steam,wemustlookbackatthepreviousachievementsinthisfield.Thefirstofthesewasthedemonstrationthatteleportationispossibleinthequantumworld.ThelateIsraeliphysicist,AsherPeres,whodiedin2005,anticipatedthephenomenoninthePhysicalReviewLettersin1993.Whenareporteraskedhimifquantumteleportationcouldtransportthesoulaswellasthebody,thephysicistreplied:“Notthebody,justthesoul.”Thisanecdoteissignificantforunderstandingquantumteleportation,whereitisnotmatterthatistransportedthroughamediumbuttheinformationthatconfersitsproperties.AsHansonexplains:“Thekeyfeatureofquantumteleportationisthatthequantuminformationitselfisactuallyteleported:itdoesnottravelthroughspaceorfiber.Theentangledpairofqubits,whichistheresourceforexecutingtheteleportation–the‘teleporter’–ispreparedbyusingasignalthroughfiber.”AnothertermforthisphenomenonwascoinedbyAlbertEinstein:“Spookyactionatadistance.”Hehimselfdeemeditimpossible.Diagramofteleportationpublishedin‘Nature.’Thus,whenoneparticleispreviouslyentangledwithanother,bothceasetobeindividualparticleswithdefinedstatesoftheirownandbecomeasystemwithasinglewavefunction.AndanymeasurementthatoccursinAliceisreplicatedinstantaneouslyinBob.ThisishowHansonexplainsit:“Measuringoneofthemimmediatelycausestheothertoalsochooseastate;inasense,measuringonealsomeasurestheother.Thisisverydifferentfromqubitmanipulation:ifwerotateAlice,nothinghappenstoBob.Therefore,thespookyactionatadistance[thatEinsteinspokeof]onlyreferstotheinstantaneouscorrelationinthemeasurementresults.Ifotherthingsbesidesmeasurementwerealsotransferredinstantaneously,itwouldactuallybepossibletosendmessagesfasterthanthespeedoflight.”Teleportationhasbeenunderexperimentforaquarterofacentury,startingwithphotonsandmovingontoatomsandmorecomplexsystems.Fiveyearsago,Jian-WeiPan,theleadingresearcherinthisfieldwhoworksatChina’sUniversityofScienceandTechnology,succeededalongwithhisteaminteleportingphotonsfromEarthtotheartificialsatelliteMicius,orbitingatanaltitudeof1,400kilometers.Jian-WeiPanhimselfexplainedtoELPAÍShowtheseachievements,whicharefundamentaltoquantumcomputing,havetoovercomea“formidablechallenge”intheshapeofthepresenceofnoiseandimperfections.“Weneedtousequantumerrorcorrectionandfault-tolerantoperationstoovercomethenoiseandscaleupthesystem,”hesaidearlierthisyear.Ifthepresenceofnoiseandimperfectionscancauseaquantumoperationtofailonasingularcomputerinlaboratoryconditions,theproblemismultipliedinanetworkedoperation.AndthishasbeenHansonandhisteam’smainachievement:efficientquantumteleportationbetweennon-adjacentnodesinanetwork.Alice,thereceiveroftheteleportedquantuminformation.Insidetheblackaluminumcylinder,thediamondsampleiscooledto-270°Ctoreduceambientnoiseandenablequantumcontrol.MariekedeLorijnTheDutchresearcherexplains:“Noiseandimperfectionsareachallengeforquantuminformationprocessing.Inaquantumnetwork,sendinginformationacrossnodescouldbedonethroughtheintermediatefibers,butthatwouldmakethequantuminformationsubjecttonoiseandfiberchannellosses.Incontrast,teleportationallowsquantuminformationtobesentbetweendistantnodeswithoutinterferencefromthesesourcesofnoise.Teleportationrequiresentanglementasaresource.BobhelpscreatethatentanglementbetweenAliceandCharlie,whodonotshareadirectphysicalconnection.”TheprocesscomesontheheelsofpreviousresearchwhereHansongotanetworktofunctionbetweenadjacentnodes.Thechallengewastoaddathirdnodeandcreateastatebetweenthethreethatshowedquantumcorrelations.Inthenewexperiment,AliceandCharlielackdirectconnectiontoeachother,butbothareconnectedtoBob.AliceandBob’squantumsystemspreparetheprocessusinganintertwinedstatebetweeneachother,onewhichBobstores,freeinghimuptocreateanentanglementwithCharlie.“AfterpreparinganentanglementbetweenAliceandCharlie,thestatetobeteleportediscreatedandthenexecuted,”saysHanson.“Whathappensthenissomethingthatisonlypossibleinthequantumworld:asaresultofthemeasurement,theinformationdisappearsfromCharlie’ssideandimmediatelyappearsonAlice’sside.”“Thenecessaryprinciplesforquantumnetworks”JuanJoséGarcíaRipoll,researchscientistattheSpanishNationalResearchCouncil(CSIC)InstituteofFundamentalPhysicsandco-founderofInspiration-Q,saystheworkofHansonandhisteamisveryimportant:“Thisisaverysophisticatedexperimentthatdemonstratesalltheprinciplesnecessaryforthecreationofquantumcommunicationnetworks,”hesays.AccordingtoGarcíaRipoll,“sendingnotonlyclassicalinformation[bits]butalsoquantumstates[arbitraryqubitstates]requiresamechanismtodistributeanentangledstatebetweentwodistantpointsandaquantummemory[memoryqubit]tostoretheinformationtobetransmittedwhileestablishingthiscommunicationchannelbasedonentanglement.”Hanson’sexperimentusesNitrogen-Vacancy(NV)centers,“atypeofdiamondimpuritythatactslikeaqubitandcanbeopticallymanipulated,”saysGarcíaRipoll.“Throughtheemissionofphotons,thisqubitmakesitpossibletocreatelong-distanceentanglement.”AnNV-centerisadefectwherebyacarbonatominthediamondcrystallatticeisreplacedbyanitrogenatom(N)andaneighboringvacancy(V).AsingleNVcandetectamagneticmomentofasinglemoleculeandhaswideapplicationsinquantumtechnology.AccordingtoGarcíaRipoll,“theNV-centerorcolorcentercanalsotalktothemagneticmomentsofsurroundingatomsand,in[Hanson’s]experiment,theyusethistogainaquantummemorybypassingtheNVinformationtoanearbynuclearspin[inacarbon-13isotope].Theinformationtobesentcanbekeptsafeforalongtime,freeingtheNVtoperformthetaskofestablishingentanglementwithanothercommunicationnode.“Apartfromthequalityoftheexperiment,thedemonstrationofasophisticatedquantumcommunicationsetupwiththreenodesandveryelaboratecommunicationalgorithms,laysthegroundworkforitsextensiontoscalableentanglementdistributionandquantumcommunicationsetupsthatareverypromising,”GarcíaRipolladds.Premature,butimportantForAdánCabello,aphysicistatSevilleUniversityinsouthernSpainwhosefirstmeasurementofaquantumsequencewasrecognizedasoneofthemajoradvancesinphysics,itisstilltoosoontospeakofaquantuminternet,althoughtheexperimentissignificantasateleporttoadistantnode.Cabelloattemptstoexplaintheachievementinsimplifiedterms.“YouhaveaquantumstateinacitythatcouldbeSevilleandyouwanttosendittoanothercity,sayMadrid,”hesays.“YouneedtheretobeastateofentangledqubitsbetweenSevilleandMadrid.Thatisstandardteleportationprotocol.Theinterestingthingabouttheexperimentisthattheentanglementcanonlybeestablishedatacertaindistance.Let’ssay,intheexampleofthecities,itis500kilometers.IfyouwanttosendqubitsfromSevilletoSanSebastián,youhavetoovercomethedistancelimitation.That’swhatHansonhasmanaged:it’snolongerSeville-Madrid,it’sSeville-SanSebastián.Thedistancehasbeendoubled.”“It’safirstreviewofwhatanetworkcouldbe,”addsCabello.“It’snolongerpoint-to-point;youcanalreadystarttoinvolvemorenodes.Buttotalkaboutthequantuminternetisgettingaheadofourselves.Nevertheless,teleportingquantuminformationisveryusefulandwillhavemanyapplications,nodoubtaboutit.”Inthesamevein,physicistsOliverSlatteryandYong-SuKimhighlightthebreakthroughachievedbyHansonandhisteamasanimportantand“critical”steptowardsthecreationofasecure,next-generationquantuminternet.Theyalsostresstheimportanceoftheinnovationsdevelopedtoachievetheprocess:thepreparation,manipulationandreadingofquantumstates.However,bothphysicistspointout:“Furtherimprovementsinmultiplesystemfeatureswillbeneededtoenablemultipleroundsofteleportationandproducelarge-scalequantumnetworks.”EnglishversionbyHeatherGalloway.MoreinformationUsingjustalaptop,anencryptioncodedesignedtopreventaquantumcomputerattackwascrackedinjust53hoursRaúlLimónJian-WeiPan:‘Thenextquantumbreakthroughwillhappeninfiveyears’RaúlLimónAdherestoMoreinformationnewsletterSignuptoELPAÍSinEnglishEditionbulletinMostviewedAlexandrWangisthenewyoungestself-madebillionaireElonMusk’stransgenderdaughterseeksnamechange:‘Inolongerwishtoberelatedtomybiologicalfather’TheglobaleconomyfearsanewdownturnThefour-dayworkingweek:‘They’dhavetopaymedoubletogobacktotheoldschedule’Coastofgiants:FootprintsinSpainconfirmcoexistenceofmassiveaurochswithNeanderthalsRecomendacionesELPAÍSCursosCentrosFrancésonlineInglésonlineItalianoonlineAlemánonlineCrucigramas&JuegosCursoscursosMásterendirecciónygestióndeltalento.AmpliatusconocimientosenelsectordeRecursosHumanos.¡Especialízate!cursosMásterUniversitarioenPsicologíaenlainfanciayadolescencia.Especialízate.¡Cuposlimitados!cursosMásterenProtocolo,EventosyTurismoconprácticasen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