Quantum teleportation expands beyond neighbouring nodes

Physicists in the Netherlands have shown for the first time that quantum information can be reliably teleported between network nodes that ... Skiptomaincontent CloseMenu Browseall SUBJECTCATEGORIES Astronomyandspace Atomicandmolecular Biophysicsandbioengineering Businessandinnovation Condensedmatter Culture,historyandsociety Diversityandinclusion Educationandoutreach Environmentandenergy Ethics Instrumentationandmeasurement Materials Mathematicsandcomputation Medicalphysics Opticsandphotonics Particleandnuclear Personalities Policyandfunding Projectsandfacilities Publishing Quantum ARTICLETYPES Analysis Blog Careers Events Features Innovationshowcases Interviews News Opinionandreviews Podcast Researchupdates Videos Webinars Collections Jobs EXPLOREPHYSICSWORLD Aboutus Ourteam Ourportfolio Advertising Contactus Signin Register Signin Register Entere-mailaddress Show Enterpassword Rememberme Forgotyourpassword? Signinto Unlockallthecontentonthesite Managewhiche-mailnewslettersyouwanttoreceive Readaboutthebigbreakthroughsandinnovationsacross13scientifictopics Explorethekeyissuesandtrendswithintheglobalscientificcommunity Entere-mailaddress Thise-mailaddresswillbeusedtocreateyouraccount Registrationisfree,quickandeasy Unlockallthecontentonthesite Choosewhiche-mailnewslettersyouwanttoreceive Readaboutthebigbreakthroughsandinnovationsacross13scientifictopics Explorethekeyissuesandtrendswithintheglobalscientificcommunity Resetyourpassword Pleaseenterthee-mailaddressyouusedtoregistertoresetyourpassword Entere-mailaddress Registrationcomplete ThankyouforregisteringwithPhysicsWorld Ifyou'dliketochangeyourdetailsatanytime,pleasevisitMyaccount Close Quantum Quantum Researchupdate Quantumteleportationexpandsbeyondneighbouringnodes 25May2022 TeleportationinprogressResearchersatQuTechintheNetherlandswiththeirquantumteleportationexperiment.(Courtesy:QuTech) PhysicistsintheNetherlandshaveshownforthefirsttimethatquantuminformationcanbereliablyteleportedbetweennetworknodesthatarenotdirectlyconnectedtoeachother.Accordingtotheresearchers,whocreatedtheworld’sfirstthree-nodequantumnetworkatQuTech(acollaborationbetweentheDelftUniversityofTechnologyandTNO)in2021,thelatestworkmarksafurthersteptowardsascalablequantumInternet. Quantumnetworksofferasuper-securewayoftransferringinformationbetweendifferentlocations,ornodes.Whilethesenodescanbeconnectedusingordinaryopticalfibres,photonlosseswithinthefibreslimitthequality,orfidelity,oftheconnection:whenaphotonislost,itsquantuminformationislost,too.Usingquantumentanglementtoteleportinformationdirectlyfromonenodetoanotherremovesthislossmechanism,makingitdesirableforafuturequantumInternet. Thethree-nodenetworkdemonstratedatQuTechin2021usedquantumbits,orqubits,madefromnitrogen-vacancy(NV)centres,whicharedefectswithindiamond’slatticeofcarbonatoms.Eachnodecontainedacommunicationqubit,andonenodealsoincorporatedamemoryqubit(madefromanadjacentcarbonatom)thatcouldstorethenode’squantuminformation.Thebuildingblocksforentanglingthreenodeswerethusalreadypresent,butthesystemwasfarfromreliableatteleportingstatesconsistently. Quantumteleportation Thefirststepinteleportingquantuminformationfromasendertoareceiveristoestablishentanglementbetweentheirrespectivequbits.Performingaso-calledBellstatemeasurement(BSM)onthesender’squbitcausesitsquantumstatetoteleport–meaningthatitdisappearsfromthesender’snodeandappears,inencryptedform,atthereceiver’snode.ThequantumstatecanthenbedecryptedusingtheBSMoutcomethatissenttothereceiverviaaclassicalchannel(suchasanopticalfibre). Previously,thishadonlybeendonewithtwoadjacentnetworkpoints,traditionallycalledAliceandBob.Addingathirdpoint,Charlie,isnoeasytask,astheentanglementbetweenAliceandCharlieneedstobecreatedviaBob,theintermediatenode.Italsorequiresahighfidelitytomaketheteleportationfunctional. Optimizationsteps Toachievethishighfidelity,theQuTechresearcherscarriedoutseveralupgrades.Intheirprevioussystem,the“heralding”signalsthatindicateentanglementcamefromthesamephotodetectorsthatdetectedthephotonsusedforentanglement.This,however,canleadtofalseheraldingsignalsduetovariousundesiredprocessesgeneratingasecondphoton.Toavoidthis,theteamsetupanadditionaldetectionpaththatflagsthefalseheraldingsignalsbycatchingthesecondphoton. Qubitsupclose:Nitrogen-vacancycentreswithinadiamondsampleareusedasqubitsintheteleportationexperiment.(Courtesy:QuTech) Anotherproblemtheresearchersaddressedisspectraldiffusion,whichcausesthequbitstocomeoutofphase,loweringthefidelityoftransmission.Thisprocesshasmoreimpactforphotonsemittedatlatertimes,sotheteamshortenedthedetectionwindow. Afinalsetofimprovementsconcernedthememoryusedtostorequantuminformation.First,theteamprotectedthememoryqubitfrominteractionswithneighbouringnuclearspins.Todothis,theyintegratedamagneticfieldpulseintotheentanglingsequencethatflipsthememoryqubitatsettimeintervals,therebyaveragingouttheeffectsoftheseunwantedinteractions.Theyalsoimprovedtheirabilitytoreadthememoryqubit.Becauseoneofthememoryqubit’sstateshasamorefavourablefidelity,itsreadoutisnotsymmetric.Byrepeatingthereadoutprocess,theteamfilteredout“bad”readouts,ultimatelyincreasingthefidelity. Beammeup Followingtheseimprovements,theresearcherswereabletoteleportquantuminformationbetweenthenon-adjacentnodesofCharlieandAlice.First,theyentangledAlice’squbitandCharlie’sviaBob’s.Charliethenstoreditspartoftheentangledstateatitsmemoryqubitandpreparedthequantumstatetobeteleported.ApplyingtheBSMatCharlieteleportsthestatetoAlice.TheresearchersthensenttheBSMoutcometoAliceandretrievedthestatewithafidelityof71%–higherthantheclassicalboundof⅔,provingthattheteleportationwassuccessful. RonaldHanson,theQuTechresearcherwholedthestudy,saysthattheteam’snextstepwillbetoexpandthenumberofmemoryqubits,makingitpossibletorunmorecomplexprotocols.Anotherobjectiveistogetthetechnologyworkingoutsidealabenvironment,forexamplebyusingalready-deployedopticalfibreswithinarealnetwork.“Wearealsocooperatingwithcomputerscientiststodevelopthequantumnetworkcontrolstack–asimilarstackofcontrollayersthatcurrentlyruntheInternetweallusetoday,”hetellsPhysicsWorld. HuguesdeRiedmatten,aresearcheratICFOinBarcelona,Spain,whowasnotinvolvedinthestudy,saysthatquantumteleportationovernon-neighbouringnodesisasignificantmilestone.Inhisview,theteam’sbiggestachievementwastocombineseveralchallengingexperiments–allofwhichneedtobefullyoptimizedtoreachtherequiredfidelityforquantumteleportation–intoasingledemonstration.deRiedmattennotesthatthecurrentset-upcanuseonlyasmallpercentageoftheemittedphotons,whichlimitsitsremoteentanglementrate.However,headdsthatthiscouldbefixedbyembeddingtheNVcentresinanopticalcavitytocollectmorephotons,orbyusingotheremitters. Readmore Three-nodequantumnetworkmakesitsdebut RodneyVanMeteratJapan’sKeioUniversityalsopraisesthework,describingitasthefundamentaldifferencebetweenasimplechannelconnectingtwopartiesandanactualnetwork.Oneofthedifficulties,henotes,willbetoscaleuptolargenumbersofqubitsateachnode,butotherteamsaroundtheworldhavebeenworkingonthisproblemforNV-centrequbits.WiththeDelftteamalreadyplanningtoincreasethenumberofnodesinitsnetwork,heis,hesays,“lookingforwardtoseeingwhattheyproducenext”. TheresearchisdescribedinNature. Wanttoreadmore? Registertounlockallthecontentonthesite E-mailAddress Register MartijnBoerkamp isasciencejournalistbasedintheNetherlands IOPSciNotes™–introducingournewjournal Theopenaccessjournalforshortresearchpublicationsacrossthephysicalsciences.Findoutmore. Readprevious Diagnosticimaging Researchupdate PortableMRIdiagnosesstrokeatthepatientbedside Readnext Quantummechanics Researchupdate Experimentswithquantumcauseandeffectrevealhiddennonclassicality DiscovermorefromPhysicsWorld Ultracoldmatter Researchupdate Lasercoolingofpolyatomicmoleculesbringsultracoldchemistryintothespotlight Quantum News QuantumentanglementoftwomacroscopicobjectsisthePhysicsWorld2021BreakthroughoftheYear Instrumentationandmeasurement Podcast SeekingthewarmglowoftheUnruheffect,reconfigurablehardwaredrivesinnovationintestandmeasurement Relatedjobs CantonofZürich|ZurichInstruments ApplicationScientistQuantumComputing(80-100%) Lancaster|LancasterUniversity ResearchFellow(x2)incondensed-matteratomicclocks France|Optica Technical&MarketExpertDirector-IndustryEngagement Relatedevents Low-temperaturephysics|Conference InternationalConferenceonCryocrystalsandQuantumCrystals 26June—1July2022|Wrocław,Poland Quantum|Virtualevent QuantumHorizons:DevelopmentsandOpportunitiesI–SummerPreparatorySchool 27—30June2022 Quantum|Virtualevent QuantumHorizons:DevelopmentsandOpportunitiesII–SummerResearchSchool/Workshop 1—15July2022 Copyright©2022byIOPPublishingLtdandindividualcontributors bright-rec ioppub iop-science physcisconnect