Overview
Quantumcomputer,simplyput,itisamachinethatcanrealizequantumcomputing,itisakindofmathematicalandlogicaloperationthroughthelawsofquantummechanics,processingandstoringinformationAbilitysystem.Itusesquantumstatesasthememoryunitandinformationstorageform,andusesquantumdynamicstoevolveasthebasisofquantumcommunicationandquantumcomputingforinformationtransmissionandprocessing.Inquantumcomputers,thesizeofvarioushardwarecomponentsreachestheorderofatomsormolecules.Aquantumcomputerisaphysicalsystemthatcanstoreandprocessinformationrepresentedbyqubits.
Justasthetraditionalcomputerrealizesthedistinctionbetween0and1throughtheon-offofthecircuitintheintegratedcircuit,anditsbasicunitisthesiliconchip,thequantumcomputeralsohasitsownbasicunit-quintessence(qubit).Quinbitisalsocalledqubit,itexpresses0or1throughthequantummechanicalsystemoftwostatesofquantum.Forexample,thetwoorthogonalpolarizationdirectionsofphotons,thespindirectionofelectronsinamagneticfield,orthetwodirectionsofnuclearspin,thetwodifferentenergylevelsofthequantuminanatom,orthespatialmodeofanyquantumsystem,etc.Theprincipleofquantumcomputingistoevolvethequantumstateinaquantummechanicalsystem.
Composition
Quantumcomputers,likemanycomputers,arecomposedofalotofhardwareandsoftware.Thesoftwareincludesquantumalgorithms,quantumcoding,etc.,andthehardwareincludesquantumtransistorsandquantummemories.,Quantumeffector,etc.
Quantumtransistorsbreakthroughthephysicalenergylimitthroughthehigh-speedmovementofelectrons,therebyrealizingtheswitchingfunctionofthetransistor.Thiskindoftransistorcontrolstheswitchingspeedveryfast,andthetransistorhasamuchstrongercomputingpowerthanordinarychips.Theabilitytoadapttotheenvironmentalconditionsusedisverystrong,sointhefuturedevelopment,thetransistorisanindispensablepartofthequantumcomputer.Quantumstorageisastoragewithhighefficiencyinstoringinformation.Itcanassignvaluestoanycalculationinformationinaveryshorttime.Itisanindispensablepartofaquantumcomputerandoneofthemostimportantpartsofaquantumcomputer.Theeffectorofaquantumcomputerisalarge-scalecontrolsystemthatcancontroltheoperationofvariouscomponents.Thesecomponentsoccupyamajorpositioninthedevelopmentofquantumcomputersandplayanimportantrole.
Principle
Quantumcomputerisakindofcomputerthatworksbasedonquantumtheory.Tracingbacktothesource,thecontinuousexplorationofreversiblemachineshaspromotedthedevelopmentofquantumcomputers.Quantumcomputerdevicesfollowthebasictheoryofquantumcomputing,processingandcalculatingquantuminformation,andrunningquantumalgorithms.In1981,PaulBenioffoftheAragonNationalLaboratoryintheUnitedStatesfirstproposedthebasictheoryofquantumcomputing.
1.Qubit
Thebasicunitofclassicalcomputerinformationisthebit.Abitisaphysicalsystemwithtwostates,representedby0and1.Inquantumcomputers,thebasicunitofinformationisaqubit,andtwoquantumstates│0>and│1>areusedtoreplacetheclassicalbitstates0and1.Comparedwithbits,qubitshaveuniquecharacteristicsofexistence.Theyexistintheformofsuperpositionoftwologicalstates,whichmeansthesuperpositionoftwocorrespondingquantumstatesof0and1.
2.Theprincipleofstatesuperposition
Thecoretechnologyofmodernquantumcomputermodelsistheprincipleofstatesuperposition,whichisabasicprincipleofquantummechanics.Inasystem,everypossiblewayofmovementiscalledastate.Inthemicrosystem,thestateofmotionofthequantumcannotbedetermined,anditisstatistical,contrarytothestateofmotiondeterminedbythemacrosystem.Thequantumstateisthestateofthemicroscopicsystem.
3.Quantumentanglement
Quantumentanglement:Whentwoparticlesareentangledwitheachother,thebehaviorofoneparticlewillaffectthestateoftheotherparticle.Thisphenomenonhasnothingtodowithdistance.Intheory,evenFarenoughapart,quantumentanglementcanstillbedetected.Therefore,whenthestateofoneofthetwoparticleschanges,thatis,whenthisparticleismanipulated,thestateoftheotherparticlewillalsochangeaccordingly.
4.Theprincipleofquantumparallelism
Quantumparallelcomputingisthemostcompellingadvancedtechnologythatquantumcomputerscansurpassclassicalcomputers.Quantumcomputersstorenumbersinexponentialform.Byincreasingthenumberofqubitsto300qubits,theycanstoremorenumbersthanalltheatomsintheuniverseandcanperformoperationsatthesametime.Thefunctioncalculationdoesnotusetheclassicalcyclicmethod,butcanbeobtaineddirectlythroughtheunitarytransformation,whichgreatlyreducestheworklossenergyandtrulyrealizesthereversiblecalculation.
Researchprogress
Intheearly1980s,Beniofffirstproposedtheideaofquantumcomputing.HedesignedanexecutablequantumTuringmachinewithclassicalanalogy—quantumcomputerPrototype.
In1982,FeynmandevelopedBenioff’svision,proposingthatquantumcomputerscansimulateotherquantumsystems.Inordertosimulatequantummechanicalsystems,Feynmanproposedtheconceptofworkingcomputersinaccordancewiththelawsofquantummechanics,whichisconsideredtheearliestideaofquantumcomputers.
In1985,DavidDeutschofOxfordUniversityprovedthatanyphysicalprocesscanbewellsimulatedbyaquantumcomputerinprinciple,andproposedacomputersimulationbasedonquantuminterference,thatis,"quantumlogic".Thenewconceptof"gate"pointsoutthegeneralizationofquantumcomputersandthegenerationandcorrectionoferrorsinquantumcalculations.In-depthanalysisandresearchweredonebyZurek.Butbythemid-1980s,thisfieldofresearchwasleftoutforseveralreasons.Firstofall,becauseallquantumcomputermodelsatthetimeregardedquantumcomputersasanisolatedsystemthatdidnotinteractwiththeexternalenvironment,ratherthanactualmodels.Secondly,therearemanyconstraintsthatarenotconducivetotherealizationofquantumcomputers,suchasdecoherenceandthermalnoisepointedoutbyLandauer.Inaddition,quantumcomputersmaybeerror-proneandnoteasytocorrect.Finally,itisunclearwhetherquantumcomputerssolvemathematicalproblemsfasterthanclassicalcalculations.
In1994,Dr.PererShorofAT&Tdiscoveredaneffectivequantumalgorithmforfactorization.In1996,S.LoydprovedFeynman'sconjecture.Hepointedoutthatsimulatingtheevolutionofquantumsystemswillbecomeanimportantuseofquantumcomputers,whichcanbebuiltonthebasisofquantumTuringmachines.Sincethen,withtherapidprogressofinterdisciplinaryresearchbetweencomputerscienceandphysics,thetheoreticalandexperimentalresearchofquantumcomputinghasflourished.Asthedevelopmentofquantumcomputershasbeguntoenteranewera,governmentsandmajorcompanieshavealsoformulatedaseriesofresearchanddevelopmentplansforquantumcomputers.
Firstofall,theAdvancedResearchProjectsAgencyoftheUnitedStatesformulatedaresearchplannamed"QuantumInformationScienceandTechnologyDevelopmentPlan"inversion1.0andversion2.0inDecember2002andApril2004.TheplandetailsthemainstepsandtimetableforthedevelopmentofquantumcomputingintheUnitedStates.Intheplan,theUnitedStateswillstrivetodevelopacomputerwith10physicalqubitsin2007andacomputerwith50physicalqubitsby2012.TheUSArmyalsoplanstoequipitsweaponswithquantumcomputersby2020.
Europehasalsomadeactiveresearchanddevelopmentinquantumcomputingandquantumencryption.Theresearchonthedispersionandentanglementofdifferentquantumsystems(suchasatoms,ionsandresonances)aswellastheresearchonquantumalgorithmsandinformationprocessinginthefifthframeworkplanhasbeencompleted.Atthesametime,inthesixthframeworkplan,thefocuswillbeonresearchingquantumalgorithmsandencryptiontechnology,anditisexpectedthatby2008,ahighlyreliable,long-distancequantumdataencryptiontechnologywillbesuccessfullydeveloped.
Japanstartedafive-yearquantumcomputingandinformationprojectinOctober2000,focusingonthecomplexityofquantumcomputingandquantumcommunication,designingnewquantumalgorithms,developingrobustquantumcircuits,andfindingquantumTheusefulfeaturesofself-controlandthedevelopmentofquantumcomputingsimulators.
In2007,theCanadianDWavecompanysuccessfullydevelopeda16-kbit"Orion"quantumcomputer,whichwaslaunchedinCalifornia,USAandVancouver,CanadaonFebruary13thandFebruary15th,2008.Showofftheirquantumcomputer.
OnNovember15,2009,theNationalInstituteofStandardsandTechnologyoftheUnitedStatesdevelopedaquantumcomputerthatcanprocesstwoquintessentialdata.
D-Wave,theworld’sfirstquantumcomputingcompany,announcedonJune22,2015thatithadbrokenthroughthe1000qubitbarrieranddevelopedanewprocessorwiththepreviousgenerationofqubits.TheD-Waveprocessorisabouttwiceasfast,andfarsurpassesthequbitsofDWaveoranyotherproductsdevelopedbyitspeers.
OnMarch6,2017,IBMannouncedthatitwilllaunchtheworld'sfirstcommercial"universal"quantumcomputingserviceIBMduringtheyear.IBMsaidthatthisserviceisequippedwiththeabilitytoaccessdirectlythroughtheInternet,andhasatransformativeroleindrugdevelopmentandvariousscientificresearches.Ithasbeguntorecruitconsumerusers.InadditiontoIBM,othercompaniessuchasIntel,Google,andMicrosoftarealsoexploringthefieldofpracticalquantumcomputers.
OnMay3,2017,theopticalquantumcomputerexperimentalprototypebuiltbythePanJianweiteamoftheChineseAcademyofScienceshassurpassedthatofearliercomputers.Inaddition,theChinesescientificresearchteamcompletedthemanipulationof10superconductingqubits,successfullybreakingtherecordofentanglementandcompletemeasurementofthesuperconductingqubitwiththelargestnumberofbitsintheworld.
OnJune18,2020,theChineseAcademyofSciencesannouncedthatPanJianwei,YuanZhensheng,etc.oftheUniversityofScienceandTechnologyofChinahavemadeimportantprogressinultra-coldatomicquantumcomputingandsimulationresearch-proposedtheoreticallyandrealizedexperimentallyOnthebasisofthenewmechanismofatomicdeepcooling,thesimultaneouspreparationof1250pairsofatomicentangledstateswithhighfidelitywasrealizedforthefirsttimeintheopticallattice,whichlaidthefoundationforthelarge-scalequantumcalculationandsimulationbasedontheultracoldatomicopticallattice.Thisresultwaspublishedonlineintheacademicjournal"Science"onthe19th.
OnDecember4,2020,theUniversityofScienceandTechnologyofChinaannouncedthatPanJianweiandothershadsuccessfullybuilta76-photonquantumcomputingprototype"NineChapters",anditonlytakes200secondstosolvethemathematicalalgorithmGaussianBosesampling,Andthefastestsupercomputerintheworldcurrentlytakes600millionyears.ThisbreakthroughmadeChinathesecondcountryintheworldtoachieve"quantumsuperiority".OnDecember4,theinternationalacademicjournal"Science"publishedtheresult,andthereviewersevaluateditas"amostadvancedexperiment"and"amajorachievement".
OnFebruary8,2021,HefeiBenyuanQuantumTechnologyCo.,Ltd.,aplatformforthetransformationofscientificandtechnologicalachievementsoftheKeyLaboratoryofQuantumInformationoftheChineseAcademyofSciences,releasedthequantumcomputeroperatingsystem"JinyuanSinan"withindependentintellectualpropertyrights.
OnJuly27,2021,theUniversityofTokyoandIBMofJapanannouncedthatcommercialquantumcomputershavebeenputintouse,whichisthefirsttimeinJapan.
Difficulties
1.Quantumdecoherence
Thecoherenceofquantumcomputingistheessenceofquantumparallelcomputing,butinactualsituations,qubitswillbeaffectedbytheoutsideworld.Theroleandinfluenceoftheenvironment,resultinginquantumentanglement.Quantumcoherenceiseasilydisturbedbyquantumentanglement,whichleadstoadecreaseinquantumcoherence,whichistheso-calleddecoherencephenomenon.Inpracticalapplications,thecontactbetweenthequbitandtheoutsideworldcannotbeavoided,andthecoherenceofthequantumisnoteasilymaintained.Therefore,theproblemofquantumdecoherenceisoneoftheimportantproblemsthatneedtobesolvedatpresent,anditssolutionwillaffectthefuturedevelopmentofquantumcomputerstoacertainextent.
2.Quantumentanglement
Asthesmallestparticle,quantumobeysthelawofquantumentanglement.Eveninspace,quantamaybeseparated,butthemutualinfluencebetweenquantaisunavoidable.Inbetween,quantumentanglementtechnologyisassociatedwiththefieldofquantuminformationtransmission.Inacertainsense,therapidcommunicationspeedbetweenquantaisusedtorealizethetransferofinformation.
3.Quantumparallelcomputing
Theuniqueparallelcomputingofquantumcomputersisanimportantpointthatclassicalcomputerscannotmatch.Itisalsoann-bitmemory,andthereisonlyoneresultstoredinaclassiccomputer.Buttheresultsstoredbythequantumcomputercanreach2n.Itsparallelcomputingnotonlyfarsurpassesthelatterinstoragecapacity,butalsohasafastreadingspeed,andmultiplereadingsandcalculationscanbeperformedatthesametime.Itispreciselytheimportanceofquantumparallelcomputing,anditseffectiveapplicationhasbecomeoneofthekeystothedevelopmentofquantumcomputers.
4.Quantumunclonability
Quantumunclonabilityreferstotheprocessinwhichthereisnoreplicationofanyunknownquantumstate.Sinceitisnecessarytokeepthequantumstateunchanged,thereisnoquantumMeasurement,itisimpossibletoachievereplication.Forquantumcomputers,theerrorcorrectionapplicationsandreplicationfunctionsofclassicalcomputerscannotberealized.
Advantages
Quantumcomputershavepowerfulquantuminformationprocessingcapabilities.Forthecurrentmassiveamountofinformation,effectiveinformationcanbeextractedandprocessedtomakeitnewandusefulinformation.Theprocessingofquantuminformationfirstrequiresthestorageandprocessingofthequantumcomputer,andthenthequantumanalysisofthegiveninformation.Usingthismethodcanaccuratelypredictweatherconditions.Atpresent,theaccuracyrateofweatherconditionspredictedbycomputersis75%.However,theuseofquantumcomputersforpredictioncanfurtherincreasetheaccuracyrateandmakeitmoreconvenientforpeopletotravel.
Currentcomputersareusuallyattackedbyviruses,whichdirectlyleadtocomputerparalysisandthetheftofpersonalinformation.However,duetothequantumprincipleofnon-cloning,theseproblemswillnotexistinquantumcomputers.WhenusersusequantumYoucansafelysurftheInternetatyourcomputerwithoutfearofpersonalinformationleakage.Ontheotherhand,quantumcomputershavepowerfulcomputingcapabilitiesandcananalyzealargenumberofdifferentdataatthesametime,sotheycanaccuratelyanalyzefinancialtrendsinfinanceandplayagreatroleinavoidingfinancialcrises;theycanalsobeusedinbiochemicalresearch.Playagreatrole,cansimulatethecompositionofnewdrugs,anddevelopdrugsandchemicalproductsmoreaccurately,sothatthecostofdrugsandthepropertiesofdrugscanbeguaranteed.
Applicationprospects
Theoretically,quantumcomputershavetheabilitytosimulatearbitrarynaturalsystemsandarealsothekeytothedevelopmentofartificialintelligence.Duetothepowerfulcapabilitiesofquantumcomputersinparalleloperations,ithastheabilitytoquicklycompletecalculationsthatcannotbedonebyclassicalcomputers.Thisadvantagehashugeapplicationsinfieldssuchasencryptionanddeciphering.
(1)Weatherforecast:Ifweuseaquantumcomputertoanalyzealltheinformationatthesametimeandgettheresult,thenwecanknowtheprecisedirectionoftheweatherchange,therebyavoidingalotofeconomicloss.
(2)Drugdevelopment:Quantumcomputersalsohavegreatadvantagesforthedevelopmentofnewdrugs.Quantumcomputerscanmapoutthecompositionoftrillionsofmoleculesandchoosethemostpossiblemethodamongthem.Itwillincreasethespeedofpeopleinventingnewdrugsandbeabletoanalyzepharmacologymorepersonalized.
(3)Trafficscheduling:Quantumcomputerscanpredicttrafficconditionsbasedonexistingtrafficconditions,completein-depthanalysis,andperformtrafficschedulingandoptimization.
(4)Confidentialcommunication:Notonlyfortheaspectsofourlives,quantumcomputerswillnotbeabletodecipheranddecipherwithoutbeingdiscoveredduetoitsunclonableprincipleforencryptedcommunication.Eavesdropping,thisisdeterminedbythenatureofthequantumcomputeritself.